Patent Grant
10703804
This application contains a sequence listing, which is submitted electronically via EFS-Web as an ASCII formatted sequence listing with a file name “Sequence Listing_688097-348U1”, creation date of Mar. 19, 2019, and having a size of 722.7 KB. The sequence listing submitted via EFS-Web is part of the specification and is herein incorporated by reference in its entirety.
The present invention relates to the field of medicine. The invention provides binding molecules, in particular single domain antibodies and multi-domain antibodies binding to influenza hemagglutinin of influenza A and/or B viruses. Preferably, the binding molecules are also capable of neutralizing influenza A and/or B viruses. The invention further provides nucleic acid molecules encoding the single domain antibodies and multi-domain antibodies, as well as compositions comprising the same. The invention further relates to the diagnosis, prophylaxis and/or treatment of an infection caused by influenza A and/or influenza B viruses.
Seasonal influenza A is a major public health problem, killing more than 250,000 worldwide each year, while creating an economic burden for millions. Pandemic influenza, which occurs when a new virus emerges and infects people globally that have little or no immunity, represents even a greater threat to human health; for example, the 1918 “Spanish Flu” pandemic caused an estimated 50 million deaths. Of continuing concern is highly pathogenic avian influenza (HPAI) which has demonstrated mortality rates of greater than 50% in infected humans. H5 as well as H7 influenza viruses are endemic in poultry in certain parts of the world. These viruses currently do not appear to be able to transmit readily from person to person, but recent data for avian H5 indicate that only a few amino acid changes are sufficient to enable this virus to spread through aerosol transmission in a mammalian in vivo model system.
To date, less attention has been paid to influenza B viruses. This may be due to the fact that—primarily being restricted to humans as host—influenza B viruses lack the large animal reservoirs that are key to the emergence of pandemic influenza A strains. However, the cumulative impact of annual epidemics exceeds that of pandemics and although the morbidity and mortality rates attributable to influenza B are lower than those of e.g. H3N2 viruses, they are generally higher than those of H1N1 viruses.
Although vaccines are the mainstay of influenza virus infection control, their timely implementation presents several technical challenges. These include (i) prediction of which viral strains will emerge and infect the human population, (ii) the lag period between the appearance of a new viral strain and the availability of a clinically approved vaccine, (iii) poor immunogenicity in certain patient groups, for example the elderly, very young or immune-compromised, and (iv) limited worldwide production capacity.
Anti-viral drugs such as the neuraminidase inhibitors oseltamivir and zanamivir and the M2 inhibitors amantadine and rimantadine are an important addition to the arsenal of treatment options against both seasonal and pandemic influenza. However, these drugs have limited efficacy if administered late in infection and widespread use is likely to result in the emergence of resistant viral strains. Furthermore the use of oseltamivir in adults is associated with adverse effects, such as nausea, vomiting, psychiatric effects and renal events.
Antibodies represent one of the earliest classes of protective agents and the passive transfer of serum from convalescent patients was used successfully during previous influenza pandemics. However, this approach has limited potential for implementation on a global scale due to (i) restricted supply of appropriate sera, (ii) high risk of toxicity, (iii) high lot-to-lot variation, (iv) uncertain dosing and (v) difficulties in administration.
Advances in recombinant monoclonal antibody technology have made this strategy worthy of further investigation, not in the least because unlimited quantities of protective antibodies can be produced and stock-piled to provide immediate protection in a pandemic emergency. For this to be an effective strategy such antibodies would be required to have neutralizing activity across different viral subtypes. This presents a major challenge as the viral coat proteins, in particular hemagglutinin (HA), of influenza viruses are constantly changing.
Hemagglutinin or HA is a trimeric glycoprotein that is anchored to the influenza viral coat and has a dual function: it is responsible for binding to the host cell surface receptor sialic acid and, after uptake, it mediates the fusion of the viral and endosomal membrane leading to release of the viral RNA in the cytosol of the cell. HA comprises a large and variable head domain and a smaller more-conserved stem domain. Most neutralizing antibodies against HA recognize epitopes in the hypervariable regions in the head region and thus interfere with binding to host cells. Recently, however new monoclonal antibodies have been identified that bind to the HA stem region and interfere with membrane fusion (Corti et al., 2011; Dreyfus et al., 2012; Ekiert et al., 2009, Ekiert et al., 2011 and Ekiert et al., 2012; Kashyap et al., 2010; Krause et al., 2012; Lee et al., 2012; Sui et al., 2009; Tan et al., 2012; Throsby et al., 2008; Tsibane et al., 2012; Wang et al., 2010; Yoshida et al., 2009).
At least some of these broadly neutralizing antibodies have shown an unprecedented breadth of cross-reactivity, enabling them to neutralize many different strains within a subtype, phylogenetic group or even between different groups and subtypes of influenza virus. The therapeutic and prophylactic potential of these antibodies has been demonstrated in both mouse and ferret models, and several are now being evaluated in human clinical trials. However, these monoclonal antibodies may also have some inherent limitations which present a major challenge to their broad application in influenza prevention and/or treatment. These limitations may include (i) requirement of parenteral administration; (ii) high cost of goods; (iii) incomplete coverage of circulating influenza strains; (iv) low bioavailability at the site of infection; and (v) risk of emerging drug resistance.
Single domain antibodies (sdAbs) are antibody fragments consisting of a single antigen-binding variable domain. These fragments have several advantages over conventional monoclonal antibodies including; (i) small size (15 kDa), (ii) low cost microbiological production, (iii) simple engineering into multi-specific formats, (iv) high stability with the potential to support non-injectable routes of administration, and/or (iv) potential to access buried or hidden epitopes. These favorable properties make sdAbs an attractive alternative to monoclonal antibodies, especially in the area of infectious disease. Neutralizing sdAbs against several different viruses have been described in literature including HIV, Hepatitis B virus, Respiratory Syncytial virus, Rabies virus, FMDV, Poliovirus and Rotavirus (Vanlandschoot et al., 2011).
HA binding sdAbs that are capable of neutralizing influenza have also been described in literature. Thus, Hultberg et al. (2011) identified an sdAb (Infl-C8) with neutralizing activity against multiple H5N1 viruses. Infl-C8 dimers and trimers showed improved and broadened activity against H5N1 viruses. However, no cross-neutralization of PR8 (H1N1) or X47 (H3N2) influenza viruses was observed.
WO2009/147248 discloses several sdAbs showing heterosubtypic binding activity in ELISA. However, none of these sdAbs, except one, was active in a virus neutralization assay. This one neutralizing sdAb, called IV146, showed phylogenetic group 1 restricted binding in ELISA and was capable of neutralizing 2 different H5 viruses.
Tillib et al. (2013) describe multiple sdAbs with in vitro and in vivo neutralizing activity against the H5N2 strain A/Mallard duck/Pennsylvania/10218/84.
Hufton et al. (2014) identified several sdAbs with cross-subtype neutralizing activity against H1, H2, H5 and/or H9 viruses. None of these sdAbs however was able to neutralize H7N2. Dimerization of one of the sdAbs improved its activity towards H1, H2, H5 and H9 but did not result in cross-group neutralization of H7N2 or H3N2 viruses.
None of the monomeric or multimeric sdAbs identified to date thus are able to neutralize all relevant seasonal (H1N1, H3N2 and B) and pandemic (e.g. H5N1 and H7N9) influenza strains. In view of the severity of respiratory illness caused by influenza A and influenza B viruses, as well has the high economic impact of the seasonal epidemics, and the continuing risk for pandemics, there is an ongoing need for new effective inhibitors with broad activity against influenza A and B viruses and which can be used as medicaments for prevention or treatment of influenza infection.
The present invention provides novel single domain antibodies (sdAbs) capable of specifically binding to hemagglutinin (HA) of at least two influenza A virus strains, said at least two influenza virus strains comprising HA of two different subtypes from phylogenetic group 2; or capable of specifically binding to at least one influenza A strain from phylogenetic group 1 and at least one influenza A virus strain from phylogenetic group 2; or capable of specifically binding to hemagglutinin (HA) of at least one influenza B virus strain. In certain embodiments, the sdAbs are also capable of neutralizing at least two different influenza A virus strains comprising two HA different subtypes from phylogenetic group 2; or at least one influenza A virus strain from phylogenetic group 1 and at least one influenza A virus strain from phylogenetic group; or at least one influenza B virus strain.
The present invention further provides so-called multi-domain antibodies, i.e. binding molecules comprising at least two, preferably at least three, more preferably at least four, or even more preferably at least five, single domain antibodies as described herein. In certain embodiments, the multi-domain antibodies are capable of neutralizing at least one influenza A virus strain from phylogenetic group 1 and at least one influenza A virus strain from phylogenetic group 2. In certain embodiments, the multi-domain antibodies are capable of neutralizing at least one influenza A virus strain from phylogenetic group 1 and at least one influenza A virus strain from phylogenetic group 2 and at least one influenza B virus strain, preferably at least one influenza B virus strain from the B/Yamagata lineage and at least one influenza virus strain from the B/Victoria lineage. In certain embodiments, the multi-domain antibodies are capable of neutralizing influenza viruses comprising HA of the H1 subtype (such as H1N1 influenza virus strains), influenza viruses comprising HA of the H3 subtype (such as H3N2 influenza virus strains), influenza viruses comprising HA of the H5 subtype (such as H5N1 influenza virus strains), and influenza viruses comprising HA of the H7 subtype (such as H7N9 influenza virus strains), and at least one influenza B virus, preferably at least one influenza B virus strain from the B/Yamagata lineage and at least one influenza virus strain from the B/Victoria lineage.
The invention furthermore provides nucleic acid molecules encoding the sdAbs or multi-domain antibodies, as well as vectors and host cells comprising said nucleic acid molecules.
The invention also provides (pharmaceutical) compositions comprising one or more sdAbs, multi-domain antibodies, nucleic acid molecules and/or vectors as described herein.
According to the present invention, novel influenza hemagglutinin-binding molecules are provided. The binding molecules may be single domain antibodies or multi-domain antibodies. At least some of binding molecules of the present invention are unique in that they are cross-neutralizing between phylogenetic groups, i.e. able to bind to and neutralize at least one influenza A virus strain from phylogenetic group 1 and at least one influenza A virus strain from phylogenetic group 2. In certain embodiment the binding molecules are capable of specifically binding to and neutralizing at least one influenza B virus strain, preferably at least one influenza B virus strain from the B/Yamagata lineage and at least one influenza virus strain from the B/Victoria lineage. The binding molecules and nucleic acid sequences of the present invention are suitable for use as a diagnostic, prophylactic, and/or treatment agents for influenza infections, even irrespective of the causative influenza subtype.
Some definitions of terms as used in the present invention are given below:
The term “binding molecule” as used herein refers to both single domain antibodies (monomeric binding molecules) and multi-domain antibodies (multimeric binding molecules) according to the invention.
As used herein a single-domain antibody (sdAb) is a binding molecule consisting of a single monomeric variable antibody domain that specifically binds an antigen or epitope independently of other V regions or domains. Single domain antibodies are known in the art and are usually derived from naturally occurring “heavy chain only” antibodies, i.e. heavy chain antibodies devoid of light chains. Such heavy chain only antibodies can be obtained from Camelidae species, for example in camel, llama, dromedary, or alpaca (also referred to as camelid antibodies). The variable region derived from said heavy chain only antibody is generally known as a VHH domain or single domain antibody (sdAb). A single-domain antibody as used herein also refers to an isolated single variable domain (VL or VH) from a conventional immunoglobulin comprising two heavy chains and two light chains. This immunoglobulin is preferably human, but may also comprise immunoglobulins from other mammalian species including rodents.
As used herein the term “multi-domain antibody” refers to a binding molecule comprising at least two single domain antibodies, linked to each other either directly or by a linking sequence.
The term “influenza virus subtype” in relation to influenza A viruses refers to influenza A virus strains that are characterized by various combinations of the hemagglutinin (H) and neuraminidase (N) viral surface proteins. Influenza A virus subtypes may be referred to by their H number, such as for example “influenza virus comprising HA of the H1 or H3 subtype”, or “H1 influenza virus” “H3 influenza virus”, or by a combination of an H number and an N number, such as for example “influenza virus subtype “H3N2” or “H5N1”. The term influenza virus “subtype” specifically includes all individual influenza virus “strains” within such subtype, which usually result from mutations and show different pathogenic profiles, and include natural isolates as well as man-made mutants or reassortants and the like. Such strains may also be referred to as various “isolates” of a viral subtype. Accordingly, as used herein, the terms “strains” and “isolates” may be used interchangeably.
The influenza A virus subtypes can further be classified by reference to their phylogenetic group. Phylogenetic analysis has demonstrated a subdivision of influenza hemagglutinins into two main groups: inter alia the H1, H2, H5 and H9 subtypes in phylogenetic group 1 (“group 1” influenza viruses) and inter alia the H3, H4, H7 and H10 subtypes in phylogenetic group 2 (“group 2” influenza viruses).
The antigenic variation in HA within the influenza type B virus strains is smaller than that observed within the type A strains. Two genetically and antigenically distinct subtypes, or “lineages”, of influenza B virus are circulating in humans, as represented by the B/Yamagata/16/88 (also referred to as B/Yamagata) and B/Victoria/2/87 (B/Victoria) lineages. As used herein the influenza B virus strains are referred to as influenza virus strains derived from the “the B/Yamagata lineage” or the “B/Victoria lineage”.
The term “neutralizing” as used herein in relation to the binding molecules of the invention refers to binding molecules that inhibit an influenza virus from replication, in vitro and/or in vivo within a subject, regardless of the mechanism by which neutralization is achieved. Thus, neutralization can e.g. be achieved by inhibiting the attachment or adhesion of the virus to the cell surface, or by inhibition of the fusion of viral and cellular membranes following attachment of the virus to the target cell, or by inhibiting viral egress from infected cells, and the like. The term “cross-neutralizing” or “cross-neutralization” as used herein in relation to the binding molecules of the invention refers to the ability of the binding molecules of the invention to neutralize different subtypes of influenza A and/or B viruses.
With respect to the binding molecules of the invention, the term “(immuno)specifically binding” refers to binding molecules that bind to an epitopes of a protein of interest, but which do not substantially recognize and bind other molecules in a sample containing a mixture of antigenic biological molecules. The binding may be mediated by covalent or non-covalent interactions or a combination of both.
As used herein, the term “influenza”, or “influenza virus disease” refers to the pathological condition resulting from an infection of a cell or a subject by an influenza A or B virus. In specific embodiments, the term refers to a respiratory illness caused by an influenza A or B virus. As used herein, the term “influenza virus infection” means the invasion by, multiplication and/or presence of an influenza virus in a cell or a subject.
In a first aspect of the invention, novel single domain antibodies (sdAbs) capable of specifically binding to hemagglutinin (HA) of at least two influenza A virus strains comprising HA of two different subtypes from phylogenetic group 2 are provided, i.e. sdAbs capable of specifically binding to hemagglutinin (HA) of at least two different influenza A virus strains, said strains comprising HA from two different HA subtypes from phylogenetic group 2. In addition, sdAbs that are capable of binding to HA of at least one influenza A virus strain from phylogenetic group 1 and to HA of at least one influenza A virus strain from phylogenetic group 2 are provided. Furthermore, sdAbs capable of specifically binding to HA of at least one influenza B virus strain are provided. Single domain antibodies that are capable of specifically binding to HA of two different subtypes of influenza A virus strains from phylogenetic group 2, or capable from binding to HA of influenza A virus strains from both phylogenetic group 1 (such as influenza viruses comprising HA of the H1, H2, and/or H5 subtype) and phylogenetic group 2 (such as influenza viruses comprising HA of the H3, H7 and/or H10 subtype) have not been described before. In addition, sdAbs that are capable of specifically binding to HA of influenza B viruses have also not yet been described.
The sdAbs of the invention bind to conserved neutralizing epitopes in HA. In certain embodiments, the sdAbs bind to an epitope in the stem region of the HA protein of an influenza A or B virus. In other embodiments, the sdAbs bind to an epitope in the head region of the HA protein. In certain embodiments, the sdAb binds to an epitope in the head region of the HA protein of an influenza B viruses.
In certain preferred embodiments, the sdAbs are also capable of neutralizing at least two influenza A virus strains comprising HA of two different subtypes from phylogenetic group 2. In certain embodiments, the sdAbs are capable of neutralizing preferably at least one influenza A virus strain from phylogenetic group 1 (such as e.g. an influenza virus comprising HA of the H1 or H5 subtype) and at least one influenza A virus strain from phylogenetic group 2 (such as e.g. an influenza virus comprising HA of the H3 or H7 subtype); or at least one influenza B virus strain, preferably at least one influenza B virus strain from the B/Yamagata lineage and at least one influenza virus strain from the B/Victoria lineage.
In certain embodiments, the single domain antibody according to the invention is a Camelid VHH domain, i.e. a variable domain of a so-called Camelid (heavy chain only) antibody. In further embodiments, the single domain antibody is a humanized Camelid VHH domain. Humanization of Camelid single domain antibodies requires the introduction and mutagenesis of a limited amount of amino acids in a single polypeptide chain. This is in contrast to humanization of scFv, Fab, (Fab) 2 and IgG, which requires the introduction of amino acid changes in two chains, the light and the heavy chain, and the preservation of the assembly of both chains. Methods for humanization of the camelid VHH domains are known in the art, such as for example described in WO2008/020079, WO2008/142164, WO2010/139808. Humanization of the sdAbs according to the present invention is described in Example 11.
In certain embodiments, a single domain antibody of the invention comprises:
one or more of CDR sequences selected from SEQ ID NO: 227, 228 and 229;
one or more of CDR sequences selected from SEQ ID NO: 230, 231 and 232;
one or more of CDR sequences selected from SEQ ID NO: 233, 234 and 235;
one or more of CDR sequences selected from SEQ ID NO: 236, 237 and 238;
one or more of CDR sequences selected from SEQ ID NO: 239, 240 and 241;
one or more of CDR sequences selected from SEQ ID NO: 242, 243 and 244;
one or more of CDR sequences selected from SEQ ID NO: 245, 246 and 247;
one or more of CDR sequences selected from SEQ ID NO: 248, 249, and 250;
one or more of CDR sequences selected from SEQ ID NO: 251, 252 and 253;
one or more of CDR sequences selected from SEQ ID NO: 254, 255 and 256;
one or more of CDR sequences selected from SEQ ID NO: 257, 258 and 259;
one or more of CDR sequences selected from SEQ ID NO: 260, 261 and 262;
one or more of CDR sequences selected from SEQ ID NO: 263, 264 and 265;
one or more of CDR sequences selected from SEQ ID NO: 266, 267 and 268;
one or more of CDR sequences selected from SEQ ID NO: 269, 270 and 271;
one or more of CDR sequences selected from SEQ ID NO: 272, 273 and 274;
one or more of CDR sequences selected from SEQ ID NO: 275, 276 and 277;
one or more of CDR sequences selected from SEQ ID NO: 278, 279 and 280;
one or more of CDR sequences selected from SEQ ID NO: 281, 282 and 283;
one or more of CDR sequences selected from SEQ ID NO: 284, 285 and 286;
one or more of CDR sequences selected from SEQ ID NO: 287, 288 and 289;
one or more of CDR sequences selected from SEQ ID NO: 290, 291 and 292;
one or more of CDR sequences selected from SEQ ID NO: 293, 122 and 123;
one or more of CDR sequences selected from SEQ ID NO: 124, 125 and 126;
one or more of CDR sequences selected from SEQ ID NO: 127, 128 and 129;
one or more of CDR sequences selected from SEQ ID NO: 130, 131 and 132;
one or more of CDR sequences selected from SEQ ID NO: 133, 134 and 135;
one or more of CDR sequences selected from SEQ ID NO: 136, 137 and 138; or
one or more of CDR sequences selected from SEQ ID NO: 139, 140 and 141.
The term “complementarity determining regions” (CDR) as used herein means sequences within the variable regions of binding molecules, that usually contribute to a large extent to the antigen binding site which is complementary in shape and charge distribution to the epitope recognized on the antigen. The CDR regions can be specific for linear epitopes, discontinuous epitopes, or conformational epitopes of proteins or protein fragments, either as present on the protein in its native conformation or, in some cases, as present on the proteins as denatured, e.g., by solubilization in SDS.
In certain embodiments, the single domain antibody is selected from the group consisting of:
a) a single domain antibody comprising a CDR1 region of SEQ ID NO:227, a CDR2 region of SEQ ID NO: 228, and a CDR3 region of SEQ ID NO: 229;
b) a single domain antibody comprising a CDR1 region of SEQ ID NO:230, a CDR2 region of SEQ ID NO: 231, and a CDR3 region of SEQ ID NO: 232;
c) a single domain antibody comprising a CDR1 region of SEQ ID NO:233, a CDR2 region of SEQ ID NO: 234, and a CDR3 region of SEQ ID NO: 235;
d) a single domain antibody comprising a CDR1 region of SEQ ID NO:236, a CDR2 region of SEQ ID NO: 237, and a CDR3 region of SEQ ID NO: 238;
e) a single domain antibody comprising a CDR1 region of SEQ ID NO:239, a CDR2 region of SEQ ID NO: 240, and a CDR3 region of SEQ ID NO: 241;
f) a single domain antibody comprising a CDR1 region of SEQ ID NO:242, a CDR2 region of SEQ ID NO: 243 and a CDR3 region of SEQ ID NO: 244;
g) a single domain antibody comprising a CDR1 region of SEQ ID NO:245, a CDR2 region of SEQ ID NO: 245, and a CDR3 region of SEQ ID NO: 247;
h) a single domain antibody comprising a CDR1 region of SEQ ID NO:248, a CDR2 region of SEQ ID NO: 249, and a CDR3 region of SEQ ID NO: 250;
i) a single domain antibody comprising a CDR1 region of SEQ ID NO: 251, a CDR2 region of SEQ ID NO: 252, and a CDR3 region of SEQ ID NO: 253;
j) a single domain antibody comprising a CDR1 region of SEQ ID NO:254, a CDR2 region of SEQ ID NO: 255, and a CDR3 region of SEQ ID NO: 256;
k) a single domain antibody comprising a CDR1 region of SEQ ID NO:257, a CDR2 region of SEQ ID NO: 258, and a CDR3 region of SEQ ID NO: 259;
l) a single domain antibody comprising a CDR1 region of SEQ ID NO: 260, a CDR2 region of SEQ ID NO: 261 and a CDR3 region of SEQ ID NO: 262;
m) a single domain antibody comprising a CDR1 region of SEQ ID NO: 263, a CDR2 region of SEQ ID NO: 264, and a CDR3 region of SEQ ID NO: 265;
n) a single domain antibody comprising a CDR1 region of SEQ ID NO: 266, a CDR2 region of SEQ ID NO: 267, and a CDR3 region of SEQ ID NO: 268;
o) a single domain antibody comprising a CDR1 region of SEQ ID NO: 269, a CDR2 region of SEQ ID NO: 270, and a CDR3 region of SEQ ID NO: 271;
p) a single domain antibody comprising a CDR1 region of SEQ ID NO: 272, a CDR2 region of SEQ ID NO: 273, and a CDR3 region of SEQ ID NO: 274;
q) a single domain antibody comprising a CDR1 region of SEQ ID NO: 275, a CDR2 region of SEQ ID NO: 276, and a CDR3 region of SEQ ID NO: 277;
r) a single domain antibody comprising a CDR1 region of SEQ ID NO: 278, a CDR2 region of SEQ ID NO: 279 and a CDR3 region of SEQ ID NO: 280;
s) a single domain antibody comprising a CDR1 region of SEQ ID NO: 281, a CDR2 region of SEQ ID NO: 282, and a CDR3 region of SEQ ID NO: 283;
t) a single domain antibody comprising a CDR1 region of SEQ ID NO: 284, a CDR2 region of SEQ ID NO: 285, and a CDR3 region of SEQ ID NO: 286;
u) a single domain antibody comprising a CDR1 region of SEQ ID NO: 287, a CDR2 region of SEQ ID NO: 288, and a CDR3 region of SEQ ID NO: 289;
v) a single domain antibody comprising a CDR1 region of SEQ ID NO: 290, a CDR2 region of SEQ ID NO: 291, and a CDR3 region of SEQ ID NO: 292;
w) a single domain antibody comprising a CDR1 region of SEQ ID NO: 293, a CDR2 region of SEQ ID NO: 122, and a CDR3 region of SEQ ID NO: 123;
x) a single domain antibody comprising a CDR1 region of SEQ ID NO:124, a CDR2 region of SEQ ID NO: 125 and a CDR3 region of SEQ ID NO: 126;
y) a single domain antibody comprising a CDR1 region of SEQ ID NO: 127, a CDR2 region of SEQ ID NO: 128, and a CDR3 region of SEQ ID NO: 129;
z) a single domain antibody comprising a CDR1 region of SEQ ID NO: 130, a CDR2 region of SEQ ID NO: 131, and a CDR3 region of SEQ ID NO: 132;
aa) a single domain antibody comprising a CDR1 region of SEQ ID NO:133, a CDR2 region of SEQ ID NO: 134, and a CDR3 region of SEQ ID NO: 135;
bb) a single domain antibody comprising a CDR1 region of SEQ ID NO:136, a CDR2 region of SEQ ID NO: 137, and a CDR3 region of SEQ ID NO: 138; and
cc) a single domain antibody comprising a CDR1 region of SEQ ID NO:139, a CDR2 region of SEQ ID NO: 140, and a CDR3 region of SEQ ID NO: 141.
In certain preferred embodiments, the single domain antibody is selected from the group consisting of:
a) a single domain antibody comprising a CDR1 region of SEQ ID NO: 275, a CDR2 region of SEQ ID NO: 276, and a CDR3 region of SEQ ID NO: 277;
b) a single domain antibody comprising a CDR1 region of SEQ ID NO: 284, a CDR2 region of SEQ ID NO: 285, and a CDR3 region of SEQ ID NO: 286;
c) a single domain antibody comprising a CDR1 region of SEQ ID NO:124, a CDR2 region of SEQ ID NO: 125 and a CDR3 region of SEQ ID NO: 126;
d) a single domain antibody comprising a CDR1 region of SEQ ID NO: 127, a CDR2 region of SEQ ID NO: 128, and a CDR3 region of SEQ ID NO: 129;
e) a single domain antibody comprising a CDR1 region of SEQ ID NO: 263, a CDR2 region of SEQ ID NO: 264, and a CDR3 region of SEQ ID NO: 265; and
f) a single domain antibody comprising a CDR1 region of SEQ ID NO: 133, a CDR2 region of SEQ ID NO: 134, and a CDR3 region of SEQ ID NO: 135.
According to a further embodiment, a single domain antibody according to the invention comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 1-29, or a homologous amino acid sequence. As used herein, a homologous amino acid sequence of the present invention may comprise additions, deletions or substitutions of one or more amino acids, which do not substantially alter the functional characteristics of the binding molecules of the invention. Where homologous sequence indicates sequence identity, it means a sequence which presents a high sequence identity (more than 70%, 75%, 80%, 85%, 90%, 95% or 98% sequence identity) with the parent sequence.
In certain embodiments, one or more amino acids in amino acid sequences described herein may be mutated, i.e. substituted by another amino acid. Such mutations may be introduced to prevent the occurrence of post-translational modifications. The most prevalent modifications include proteolysis, glycosylation, oxidation of methionine, and deamidation of asparagine and glutamine residues. Other modifications include pyroglutamate formation, aspartate isomerization and tryptophan oxidation. The following amino acid residues and sequence motifs are susceptible to post-translational modification and may therefore be altered by site directed mutagenesis: N-terminal glutamic acid or glutamine, N-glycosylation motif Asn-Xxx-Ser/Thr, solvent exposed methionine or tryptophan residues, proteolytic cleavage site Asp-Pro, deamidation motifs Asn-Gly and Gln-Gly and/or Asp isomerization motif Asp-Gly.
In certain embodiments, a sdAb of the invention is humanized. Thus, in certain embodiments, the sdAbs comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 146-226 and 340.
In certain embodiments, the single domain antibody according to the invention comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 13, or a humanized variant thereof selected from the group consisting of SEQ ID NO: 177-187 and SEQ ID NO: 340; SEQ ID NO: 17 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 146-156; SEQ ID NO: 20 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 157-176; SEQ ID NO: 24 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 188-197; SEQ ID NO: 25 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 198-203; and SEQ ID NO: 27 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 204-226.
In certain embodiments, the single domain antibody comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 187, SEQ ID NO: 340, SEQ ID NO: 155, SEQ ID NO: 176, SEQ ID NO: 197, SEQ ID NO: 203 and SEQ ID NO: 221.
According to second aspect of the present invention so-called multi-domain antibodies, i.e. binding molecules comprising at least two single domain antibodies as described above, are provided. For example, the C-terminal end of a first single domain antibody may be linked to the N-terminal end of a next single domain antibody to form a dimeric binding molecule. In certain embodiments, the multi-domain antibodies comprise at least three, at least four, or at least five single domain antibodies as described above to form a multimer, such as a trimer, tetramer, pentamer, etc. The linked sdAbs can be the same or can be different sdAbs, i.e. sdAbs having different amino acid sequences and epitope specificities.
In certain embodiments, the multi-domain antibodies are single chain molecules. In certain embodiments, the multi-domain antibodies are two-chain molecules, i.e. comprise at least two chains each comprising at least one single-domain antibody. The two chains may be identical or may be different.
The single domain antibodies may be linked to form any of the multi-domain antibodies disclosed herein using any methods known in the art. Thus, the single domain antibodies may be linked by chemical linkage, or may be linked together either directly or by short polypeptide linkers. Such linker sequence may be a naturally occurring sequence or a non-naturally occurring sequence. The linker sequence preferably provides sufficient flexibility to the multi-domain antibody and at the same time is resistant to proteolytic degradation.
In certain embodiment, the at least two single domain antibodies are genetically fused via peptide linkers. Thus, the single domain antibodies are fused genetically at the DNA level, by forming a polynucleotide construct (or nucleic acid sequence) encoding the complete polypeptide construct, i.e. the binding molecule comprising the two or more single domain antibodies.
In certain embodiments, the at least two single domain antibodies are linked by a linking sequence comprising from 1 to 100 amino acids, preferably from 1 to 80 amino acids, or from 1 to 60 amino acids, or from 10 to 60 amino acids. Examples of linkers include, but are not limited to, the linking sequences in Table 15. Thus, in certain embodiments the linking sequence comprises an amino acid sequence selected from SEQ ID NO: 142-145.
In certain embodiments, the multi-domain antibodies comprise at least two sdAbs according to the present invention. The at least two sdAbs may be selected from Table 14 and/or Table 40. In certain embodiments, the at least two sdAbs are selected from the group consisting of SEQ ID NO: 1-29 and SEQ ID NO: 146-226. The at least two sdAbs may be the same (homo-multimer) or may be different (hetero-multimer).
In certain embodiments, the multi-domain antibodies comprise at least two, preferably at least three, more preferably at least four sdAbs selected from the group consisting of
a) a single domain antibody comprising a CDR1 region of SEQ ID NO: 275, a CDR2 region of SEQ ID NO: 276, and a CDR3 region of SEQ ID NO: 277;
b) a single domain antibody comprising a CDR1 region of SEQ ID NO: 284, a CDR2 region of SEQ ID NO: 285, and a CDR3 region of SEQ ID NO: 286;
c) a single domain antibody comprising a CDR1 region of SEQ ID NO:124, a CDR2 region of SEQ ID NO: 125 and a CDR3 region of SEQ ID NO: 126;
d) a single domain antibody comprising a CDR1 region of SEQ ID NO: 127, a CDR2 region of SEQ ID NO: 128, and a CDR3 region of SEQ ID NO: 129;
e) a single domain antibody comprising a CDR1 region of SEQ ID NO: 263, a CDR2 region of SEQ ID NO: 264, and a CDR3 region of SEQ ID NO: 265; and
f) a single domain antibody comprising a CDR1 region of SEQ ID NO: 133, a CDR2 region of SEQ ID NO: 134, and a CDR3 region of SEQ ID NO: 135.
In certain embodiments, the multi-domain antibodies according to the invention comprise at least two, preferably at least three, more preferably at least four sdAbs selected from the group consisting of: SEQ ID NO: 13, or a humanized variant thereof selected from the group consisting of SEQ ID NO: 177-187 and SEQ ID NO: 340; SEQ ID NO: 17 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 146-156; SEQ ID NO: 20 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 157-176; SEQ ID NO: 24 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 188-177; SEQ ID NO: 25 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 198-203; and SEQ ID NO: 27 or a humanized variant thereof selected from the group consisting of SEQ ID NO: 204-226.
In certain embodiments, the multi-domain antibodies according to the invention comprise an amino acid sequence selected from the group consisting of: SEQ ID NO: 30-73.
In certain embodiments, the multi-domain antibodies of the invention are capable of neutralizing at least one influenza A virus strain from phylogenetic group 1 (such as e.g. an influenza virus comprising HA of the H1 and/or H5 subtype) and at least one influenza A virus strain from phylogenetic group 2 (such as e.g. an influenza virus comprising HA of the H3 and/or H7 subtype). In certain embodiments, the multi-domain antibodies of the invention are capable of neutralizing at least one influenza A virus strain from phylogenetic group 1 (such as e.g. an influenza virus comprising HA of the H1 and/or H5 subtype) and at least one influenza A virus strain from phylogenetic group 2 (such as e.g. an influenza virus comprising HA of the H3 and/or H7 subtype) and at least one influenza B virus strain, preferably at least one influenza B virus strain of the B/Yamagata lineage and at least one influenza virus strain of the B/Victoria lineage.
In certain embodiments, the multi-domain antibodies are capable of neutralizing influenza viruses comprising HA of the H1 subtype (such as H1N1 influenza virus strains), influenza viruses comprising HA of the H3 subtype (such as H3N2 influenza virus strains), influenza viruses comprising HA of the H5 subtype (such as H5N1 influenza virus strains), influenza viruses comprising HA of the H7 subtype (such as H7N9 influenza virus strains), and at least one influenza B virus, preferably at least one influenza B virus strain from the B/Yamagata lineage and at least one influenza virus strain from the B/Victoria lineage. The multi-domain antibodies of the present invention thus can suitably be used in the prevention and/or treatment of influenza infections, even irrespective of the causative influenza subtype.
According to the present invention it has been shown that the cross-neutralizing multi-domain antibodies of the invention offer several advantages relative to other small and large anti-influenza molecules. Thus, the affinity and potency of the multi-domain antibodies, as well as the breadth of neutralization are superior to the affinity, potency and breadth of neutralization of the published broadly neutralizing Abs (bnAbs) targeting influenza HA, like e.g. CR9114 (WO2013/007770) and FI6v3 (Corti et al., 2011). In addition, the multi-domain antibodies by targeting multiple independent neutralizing epitopes are less prone to the development of drug resistant influenza strains than CR9114 and FI6v3.
As described herein, the present invention thus provides novel influenza binding and cross-neutralizing binding molecules. The binding molecules may be monomeric, i.e. be single domain antibodies, or multimeric, i.e. multi-domain antibodies. The binding molecules of the invention bind to their target with high affinity and specificity. This is in contrast with small molecule drugs like antivirals which frequently show off-target binding resulting in unwanted side effects. In addition, the binding molecules of the invention bind to a variety of HA epitopes, some of which are inaccessible to conventional antibodies. Influenza HA contains multiple glycosylation sites both in the head and stem region. Carbohydrates attached to these sites render some parts on the HA molecule inaccessible to conventional antibodies. The smaller binding molecules of the invention are still able to target these potentially functionally important epitopes. In addition, the binding molecules of the invention are stable under a wide range of extreme conditions. They are typically resistant to elevated temperatures (up to 100° C.), extremes in pH, denaturing agents and proteolytic degradation. The favorable stability of the binding molecules may yield products that can be kept outside of the cold chain and that have longer shelf-lives than other protein drugs like monoclonal antibodies. Furthermore, the binding molecules of the invention are all single proteins which can be produced and purified following one single process.
Typically, the binding molecules according to the invention bind to HA of an influenza A virus of group 1 (such as H1N1) and/or an influenza A virus of group 2 (such as H3N2), and/or an influenza B virus, and/or fragments thereof, with an affinity constant (Kd-value) that is lower than 1.0×10−6 M, 1.0×10−7 M, preferably lower than 1.0×10−8 M, more preferably lower than 1.0×10−9 M. Affinity constants can for instance be measured using surface plasmon resonance, for example using the BIACORE system (Pharmacia Biosensor AB, Uppsala, Sweden), or as described in Example 8.
In certain embodiments, the binding molecules exhibit neutralization activity against influenza A and/or B viruses. In certain embodiment, the binding molecules of the invention prevent an influenza A or B virus from infecting host cells by at least 99%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 60%, at least 50%, at least 45%, at least 40%, at least 45%, at least 35%, at least 30%, at least 25%, at least 20%, or at least 10% relative to infection of host cells by said influenza virus in the absence of said binding molecules. Neutralizing activity can for instance be measured as described herein. Alternative assays measuring neutralizing activity are described in for instance WHO Manual on Animal Influenza Diagnosis and Surveillance, Geneva: World Health Organisation, 2005, version 2002.5. Typically, the binding molecules according to the invention have a neutralizing activity of 1000 nM or less, preferably 100 nM or less, more preferably a neutralizing activity of 10 nM or less, even more preferably 1 nM or less, as determined in an in vitro virus neutralization assay (VNA), e.g. as described in the Examples.
In certain embodiments, the binding molecules (i.e. the single domain antibodies or multi-domain antibodies) further comprise an Fc tail. Thus, in certain embodiments, the binding molecules, as described above, are linked to an Fc fragment of an antibody, preferably a human antibody, such as the Fc fragment of a human IgG antibody, e.g an IgG1, IgG2, IgG3, IgG4, or IgG4. According to the invention, the monomeric or multimeric binding molecules, as described herein, may be genetically fused to an Fc fragment, either directly or using a linker. In certain embodiments, the binding molecules are linked to the Fc fragment by a linking sequence comprising from 1 to 100 amino acids, preferably from 1 to 80 amino acids, or from 1 to 60 amino acids, or from 10 to 60 amino acids. Examples of linkers include, but are not limited to, the linking sequences in Table 15. Thus, in certain embodiments the linking sequence comprises an amino acid sequence selected from SEQ ID NO: 142-145. In certain embodiments, a sdAb or multi-domain antibody is genetically fused to the C-terminus of an Fc fragment. In further embodiments, a single domain antibody or multi-domain antibody is fused to both the N- and the C-terminus of an Fc fragment.
In certain embodiments, the Fc fragment is engineered to have minimal effector functions. Fc fragments with minimal effector function and conserved half-life have been described in the art and include e.g. IgG2, aglycosylated IgG1 (IgG1 agly), IgG4 with S228P/L234A/L235A substitutions (IgG4 ProAlaAla), IgG2 with H268Q/309UA330S/P331S changes (IgG2m4) and an Fc variant of IgG2, designated as IgG2σ, containing V234A/G237A/P238S/H268A/V309UA330S/P331S substitutions. With regard to mutated versions of IgG4, specific affinity for FcγR has been eliminated by the L234A/L245A substitutions.
In certain embodiments, the Fc fragment is engineered to have enhanced effector functions. The binding molecules of the invention thus can be engineered to enhance Fc-mediated effector functions, which in preclinical models of influenza infection have been shown to contribute to drug efficacy. Several mutations in the CH2 domain of human IgG1 associated with enhanced effector function have been described in the art. These mutations include, but are not limited to, alanine mutant at position 333 which increases both ADCC and CDC, a triple mutant (S239D/I332E/A330L) with higher affinity for FcγRIIIa and lower affinity for FcγRIIb resulting in enhanced ADCC, and another triple mutant (S239D/I332E/G236A) with improved FcγRIIIa affinity and FcγRIIa/FcγRIIb ratio that mediates enhanced phagocytosis. Other Fc mutations affecting effector functionality have been described in literature e.g. Strohl, 2009. In certain embodiments, the Fc fragment is engineered to have an extended serum half-life. Several engineered Fc backbones with increased serum half-life are known in the art. These Fc variants include, but are not limited to, hIgG1 Fc with M252Y/S254T/T256E (YTE) mutations, hIgG1 or hIgG2 Fc carrying T250Q/M428L mutations (QL), hIgG1 Fc with N434A mutation, hIgG1 Fc with T307A/E380A/N434A mutations (AAA) or hIgG1 Fc with M428L/N434S (LS) substitutions (Kuo et al., 2011). In further embodiments, the binding molecules (i.e. the single domain antibodies or the multi-domain antibodies according to the invention) are genetically fused to human serum albumin or a single domain antibody binding to serum albumin. In other embodiments, the single domain antibodies or the multi-domain antibodies according to the invention are chemically conjugated to PEG. The binding molecules of the invention thus can be engineered to have serum half-lives ranging from e.g. just a few hours to several weeks or even months. This opens the possibility for single dose treatment of influenza infection instead of a 2× daily regimen as currently used form the neuraminidase inhibitors, such as oseltamivir and zanamivir.
In further embodiments, the single domain antibody or multi-domain antibody as described above may be fused to an Fc tail, preferably an Fc tail which is engineered to promote the formation of a hetero-dimeric Fc molecule. Mutations promoting Fc-heterodimerization have been described in the art (Klein et al., 2012). In certain embodiments, the mutations promoting the FC-heterodimerization are the knobs-into-holes mutations as described in EP0812357B1 and EP0979281B1.
In certain embodiments, the multi-domain antibodies according to the present invention comprise at least one chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 74-107, SEQ ID NO: 110-121 and SEQ ID NO: 293-339.
In certain embodiments, the multi-domain antibodies comprise two chains, wherein the amino acid sequence of the two chains is identical. In certain embodiments, the two chains comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 74-105 and SEQ ID NO: 293-298. In certain embodiments, the two amino acid chains comprise an amino acid sequence of SEQ ID NO: 293-298.
In certain embodiments, the multi-domain antibodies comprise two different amino acid chains. In certain embodiments, the two different amino acid chains are selected from the group consisting of:
one chain comprising the amino acid sequence of SEQ ID NO: 299 and one chain comprising the amino acid sequence of SEQ ID NO: 300;
one chain comprising the amino acid sequence of SEQ ID NO: 301 and one chain comprising the amino acid sequence of SEQ ID NO: 302;
one chain comprising the amino acid sequence of SEQ ID NO: 303 and one chain comprising the amino acid sequence of SEQ ID NO: 305;
one chain comprising the amino acid sequence of SEQ ID NO: 306 and one chain comprising the amino acid sequence of SEQ ID NO: 307;
one chain comprising the amino acid sequence of SEQ ID NO: 308 and one chain comprising the amino acid sequence of SEQ ID NO: 309;
one chain comprising the amino acid sequence of SEQ ID NO: 310 and one chain comprising the amino acid sequence of SEQ ID NO: 311;
one chain comprising the amino acid sequence of SEQ ID NO: 312 and one chain comprising the amino acid sequence of SEQ ID NO: 313;
one chain comprising the amino acid sequence of SEQ ID NO: 315 and one chain comprising the amino acid sequence of SEQ ID NO: 315;
one chain comprising the amino acid sequence of SEQ ID NO: 316 and one chain comprising the amino acid sequence of SEQ ID NO: 317;
one chain comprising the amino acid sequence of SEQ ID NO: 318 and one chain comprising the amino acid sequence of SEQ ID NO: 319;
one chain comprising the amino acid sequence of SEQ ID NO: 106 and one chain comprising the amino acid sequence of SEQ ID NO: 317;
one chain comprising the amino acid sequence of SEQ ID NO: 320 and one chain comprising the amino acid sequence of SEQ ID NO: 321;
one chain comprising the amino acid sequence of SEQ ID NO: 322 and one chain comprising the amino acid sequence of SEQ ID NO: 323;
one chain comprising the amino acid sequence of SEQ ID NO: 324 and one chain comprising the amino acid sequence of SEQ ID NO: 325;
one chain comprising the amino acid sequence of SEQ ID NO: 326 one chain comprising the amino acid sequence of SEQ ID NO: 327;
one chain comprising the amino acid sequence of SEQ ID NO: 328 and one chain comprising the amino acid sequence of SEQ ID NO: 329;
one chain comprising the amino acid sequence of SEQ ID NO: 330 and one chain comprising the amino acid sequence of SEQ ID NO: 331;
one chain comprising the amino acid sequence of SEQ ID NO: 332 and one chain comprising the amino acid sequence of SEQ ID NO: 333;
one chain comprising the amino acid sequence of SEQ ID NO: 334 and one chain comprising the amino acid sequence of SEQ ID NO: 335;
one chain comprising the amino acid sequence of SEQ ID NO: 336 and one chain comprising the amino acid sequence of SEQ ID NO: 337; and
one chain comprising the amino acid sequence of SEQ ID NO: 338 and one chain comprising the amino acid sequence of SEQ ID NO: 339.
In certain embodiments, the two different amino acid chains are selected from the group consisting of:
one chain comprising the amino acid sequence of SEQ ID NO: 301 and one chain comprising the amino acid sequence of SEQ ID NO: 302;
one chain comprising the amino acid sequence of SEQ ID NO: 310 and one chain comprising the amino acid sequence of SEQ ID NO: 311;
one chain comprising the amino acid sequence of SEQ ID NO: 322 and one chain comprising the amino acid sequence of SEQ ID NO: 323; and
one chain comprising the amino acid sequence of SEQ ID NO: 330 and one chain comprising the amino acid sequence of SEQ ID NO: 331.
In yet another aspect, the present invention further provides nucleic acid molecules (also referred to as nucleic acid sequences) encoding the single domain antibodies or multi-domain antibodies as described above. Preferably, the nucleic acid sequences encode binding molecules comprising one or more of the CDR regions as described above.
In certain embodiments, the nucleic acid sequences encode a single domain antibody comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1-29, or a homologous amino acid sequence.
In certain embodiments, the nucleic acid sequences encode a single domain antibody comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 146-226 and SEQ ID NO: 340, or a homologous amino acid sequence.
In certain embodiments, the nucleic acid sequences encode a multi-domain antibody comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 30-107, SEQ ID NO: 110-121 and SEQ ID NO: 293-339, or a homologous amino acid sequence.
A nucleic acid sequence according to the invention refers to a polymeric form of nucleotides and includes RNA, mRNA, cDNA, genomic DNA, and synthetic forms and mixed polymers of the above. A nucleotide refers to a ribonucleotide, deoxynucleotide or a modified form of either type of nucleotide. The term also includes single- and double-stranded forms of DNA. The skilled man will appreciate that functional variants of these nucleic acid molecules are also intended to be a part of the present invention. Functional variants are nucleic acid sequences that can be directly translated, using the standard genetic code, to provide an amino acid sequence identical to that translated from the parental nucleic acid molecules.
In preferred embodiments, the nucleic acid molecules encoding the binding molecules according to the invention are codon-optimized for expression in yeast cells or mammalian cells, such as human cells. Methods of codon-optimization are known and have been described previously (e.g. WO 96/09378). A sequence is considered codon-optimized if at least one non-preferred codon as compared to a wild type sequence is replaced by a codon that is more preferred. Herein, a non-preferred codon is a codon that is used less frequently in an organism than another codon coding for the same amino acid, and a codon that is more preferred is a codon that is used more frequently in an organism than a non-preferred codon. The frequency of codon usage for a specific organism can be found in codon frequency tables, such as in http://www.kazusa.or.jp/codon. Preferably more than one non-preferred codon, preferably most or all non-preferred codons, are replaced by codons that are more preferred. Preferably the most frequently used codons in an organism are used in a codon-optimized sequence. Replacement by preferred codons generally leads to higher expression.
It will also be understood by a skilled person that numerous different nucleic acid molecules can encode the same polypeptide as a result of the degeneracy of the genetic code. It is also understood that skilled persons may, using routine techniques, make nucleotide substitutions that do not affect the amino acid sequence encoded by the nucleic acid molecules to reflect the codon usage of any particular host organism in which the polypeptides are to be expressed. Therefore, unless otherwise specified, a “nucleic acid sequence encoding an amino acid sequence” includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. Nucleic acid sequences can be cloned using routine molecular biology techniques, or generated de novo by DNA synthesis, which can be performed using routine procedures by service companies having business in the field of DNA synthesis and/or molecular cloning (e.g. GeneArt, GenScript, Life Technologies, Eurofins).
The invention also provides vectors comprising at least one nucleic acid sequence as described above. The term “vector” refers to a nucleic acid molecule into which a second nucleic acid molecule can be inserted for introduction into a host cell where it will be replicated, and in some cases expressed. In other words, a vector is capable of transporting a nucleic acid molecule to which it has been linked. Cloning vectors as well as expression vectors are contemplated by the term “vector”, as used herein. Certain vectors are capable of autonomous replication in a host into which they are introduced (e.g., vectors having a bacterial origin of replication can replicate in bacteria). Other vectors can be integrated into the genome of a host upon introduction into the host cell, and thereby are replicated along with the host genome. Vectors according to the invention can easily be made by methods well known to the person skilled in the art.
In certain embodiments, vectors comprising one or more nucleic acid molecules according to the invention operably linked to one or more expression-regulating nucleic acid sequences are provided. The term “expression-regulating nucleic acid sequence” as used herein refers to nucleic acid sequences necessary for and/or affecting the expression of an operably linked coding sequence in a particular host organism. The expression-regulating nucleic acid sequences, such as inter alia appropriate transcription initiation, termination, promoter, enhancer sequences; repressor or activator sequences; efficient RNA processing signals such as splicing and polyadenylation signals; sequences that stabilize cytoplasmic mRNA; sequences that enhance translation efficiency (e.g., ribosome binding sites); sequences that enhance protein stability; and when desired, sequences that enhance protein secretion, can be any nucleic acid sequence showing activity in the host organism of choice and can be derived from genes encoding proteins, which are either homologous or heterologous to the host organism. The identification and employment of expression-regulating sequences is routine to the person skilled in the art. Suitable vectors according to the invention are e.g. adenovectors, such as e.g. Ad26 or Ad35, adenoassociated vectors (AAV), lentivirus, alphavirus, paramyxovirus, vaccinia virus, herpes virus, retroviral vectors etc.
In certain embodiments, the vectors are used for gene therapy purposes, as for example described by Adam et al. (2014), Johnson et al. (2009) and Suscovich and Alter (2015).
The invention further provides host cells comprising a nucleic acid sequence encoding a single domain antibody or a multi-domain antibody as described herein. “Host cells”, as used herein, refers to cells into which a vector such as a cloning vector or an expression vector has been introduced. The host cells can be prokaryotic or eukaryotic.
The present invention further provides pharmaceutical compositions comprising one or more single domain antibodies, multi-domain antibodies, nucleic acid molecules and/or vectors as described above. The pharmaceutical compositions of the invention may further comprise at least one pharmaceutically acceptable excipient. By “pharmaceutically acceptable excipient” is meant any inert substance that is combined with an active molecule such as a binding molecule according to the invention for preparing a suitable composition. The pharmaceutically acceptable excipient is an excipient that is non-toxic to recipients at the used dosages and concentrations, and is compatible with other ingredients of the formulation. Pharmaceutically acceptable excipients are widely applied and known in the art. The pharmaceutical composition according to the invention may further comprise at least one other therapeutic, prophylactic and/or diagnostic agent. Said further therapeutic and/or prophylactic agents may for example be agents that are also capable of preventing and/or treating an influenza virus infection, such as for example M2 inhibitors (e.g., amantidine, rimantadine) and/or neuraminidase inhibitors (e.g., zanamivir, oseltamivir). These can be used in combination with the binding molecules of the invention. “In combination” herein means simultaneously, as separate formulations, or as one single combined formulation, or according to a sequential administration regimen as separate formulations, in any order.
In a further aspect, the present invention provides single domain antibodies, multi-domain antibodies, nucleic acid molecules, and/or vectors as described herein for use in the diagnosis, prevention and/or treatment of an influenza infection. The invention furthermore provides the use of the single domain antibodies, multi-domain antibodies, nucleic acid molecules, and/or vectors as described herein in the manufacture of a medicament for the diagnosis, prevention and/or treatment of an influenza infection. Such infections can occur in small populations, but can also spread around the world in seasonal epidemics or, worse, in global pandemics where millions of individuals are at risk. The invention provides binding molecules that can neutralize the infection of influenza strains that cause such seasonal epidemics, as well as potential pandemics. Importantly, protection and treatment can be envisioned now with the binding molecules of the present invention irrespective of the causative influenza virus, as it has been disclosed that the binding molecules of the present invention are capable of cross-neutralizing various influenza subtypes of both phylogenetic group 1, encompassing e.g. H1, H2, H5, H6, H8, H9 and H11 subtypes, and phylogenetic group 2, encompassing e.g. H3, H4, H7 and H10 subtypes, as well as influenza B subtypes.
The invention further provides methods for preventing and/or treating influenza in a subject, comprising administering a therapeutically effective amount of a single domain antibody, multi-domain antibody, nucleic acid molecule, and/or vector as described herein to a subject in need thereof. The term “therapeutically effective amount” refers to an amount of the binding molecule or nucleic acid molecule as defined herein that is effective for preventing, ameliorating and/or treating a condition resulting from infection with an influenza virus. Ameloriation as used in herein may refer to the reduction of visible or perceptible disease symptoms, viremia, or any other measurable manifestation of influenza infection. Prevention encompasses inhibiting or reducing the spread of influenza virus or inhibiting or reducing the onset, development or progression of one or more of the symptoms.
Prevention and/or treatment may be targeted at patient groups that are susceptible to influenza infection. Such patient groups include, but are not limited to e.g., the elderly (e.g. ≥50 years old, ≥60 years old, and preferably ≥65 years old), the young (e.g. ≤5 years old, ≤1 year old), hospitalized patients and already infected patients who have been treated with an antiviral compound but have shown an inadequate antiviral response.
Dosage regimens can be adjusted to provide the optimum desired response (e.g., a therapeutic response). A suitable dosage range may for instance be 0.01-100 mg/kg body weight, preferably 0.1-50 mg/kg body weight, preferably 0.01-15 mg/kg body weight. Furthermore, for example, a single bolus may be administered, several doses may be administered over time, or the dose may be proportionally reduced or increased as deemed necessary.
The binding molecules, nucleic acid molecules and/or vectors according to the invention may be administered to a subject for example intravenously, intranasally, via oral inhalation, pulmonary, subcutaneously, intradermally, intravitreally, orally, intramuscularly etc. The optimal route of administration will be influenced by several factors including the physicochemical properties of the active molecules, the urgency of the clinical situation and the relationship of the plasma concentrations of the active molecules to the desired therapeutic effect.
The high stability of binding molecules of the invention opens up the possibility for alternative, needle-free delivery, such as by intranasal administration using nose drops or nasal spray or via inhalation using a nebulizer or dry-powder inhaler. In certain embodiments, a nucleic acid molecule or vector encoding at least one single or multi-domain antibody according to the invention thus is administered intranasally, as described for example by Limberis et al. (2013).
Unlike conventional antibodies and many other biopharmaceuticals, the binding molecules of the invention can be produced very efficiently in microbial systems. Examples of microbial host cells used in large-scale manufacturing are for example yeast (P. pastoris) and E. coli. These microbial systems are considered as the most cost-effective option for biopharmaceutical manufacturing. Low COGs is a prerequisite for broad use of anti-flu drugs in influenza prophylaxis and treatment. In certain embodiments, the present invention thus provides methods for producing the binding molecules (i.e. the single domain antibodies or multi-domain antibodies) according to the invention, comprising culturing a host cell as described herein under conditions conducive to the expression of the binding molecule, and optionally, recovering the expressed binding molecule. Methods to recover the binding molecules from culture media are well known to the man skilled in the art.
In certain embodiment, the host cells are microbial cells, such as, but not limited to, yeast cells or E. coli.
In further embodiments, the host cells are mammalian cells, such as, but not limited to, CHO cells, HEK cells or PER.C6 cells.
The present invention further pertains to a method of detecting an influenza virus in a sample, wherein the method comprises the steps of a) contacting said sample with a diagnostically effective amount of a binding molecule according to the invention, and b) determining whether the binding molecule specifically binds to a molecule in the sample. The sample may be a biological sample including, but not limited to blood, serum, tissue or other biological material from (potentially) infected subjects. The (potentially) infected subjects may be human subjects, but also animals that are suspected as carriers of influenza virus might be tested for the presence of influenza virus using the binding molecules of the invention. Preferably, the binding molecules of the invention are contacted with the sample under conditions which allow the formation of an immunological complex between the binding molecules and the influenza virus or antigenic components thereof that may be present in the sample. The formation of an immunological complex, if any, indicating the presence of influenza virus in the sample, can then detected and measured by suitable means. Such methods include, inter alia, homogeneous and heterogeneous binding immunoassays, such as radioimmunoassays (RIA), ELISA, immunofluorescence, immunohistochemistry, FACS, BIACORE and Western blot analyses. The present invention is further illustrated in the following, non-limiting Examples.
With the aim to induce a heavy-chain antibody dependent immune response, four llamas (Lama glama) were immunized with influenza virus antigens (commercial vaccine Inflexal® and recombinant protein) in the presence of Freund's adjuvant according to the scheme described in Table 1.
Peripheral blood was collected from the Llamas by venipuncture in citrate anti-coagulation sample tubes at the indicated time points after the 2nd, 3rd, 4th, and 5th immunization (Table 1).
The homologues and heterologous immune response in each animal was analyzed by comparing the antigen specific serum titers of a sample collected prior to immunization (day 0) and a serum sample collected after antigen administrations (day 28 and day 112) in an HA ELISA. To this end, recombinant HA protein was captured in a Maxisorp 96-well microtiter plates. After blocking, serial dilutions of serum samples were added, and bound llama IgG was detected by addition of goat anti-llama IgG-HRP. Results are shown in
Peripheral Blood Mononuclear Cells (PBMC) were isolated from fresh blood using Ficoll-Paque plus (GE Healthcare) according to manufacturer's instructions. Total RNA extracted from PBMC served as starting material for RT-PCR to amplify the VHH encoding gene fragments. These fragments were cloned via SfiI and NotI restriction sites into M13 phagemid vector pDV-LucStuffer (pDV-C06 derived; as described in WO 02/103012) to create a fusion of VHH domain with the pIII protein of the M13 phage (including an AMBER stop codon between the two proteins). Ligated vectors were transformed into TG-1 bacteria (Agilent) and 100-150 single colonies where analysed via PCR to determine the quality of each library. Insert frequency and completeness were typically more than 95%. The characteristics of the constructed libraries are shown in Table 2. Phage libraries from individual animals were prepared by using CT helper phages essentially as described (WO 02/103012), sterile filtered, and used for selections. As shown herein, complex phage libraries could be generated from all immunized llamas.
Antibody fragments were selected using the VHH phage display libraries described above and general phage display technology and MABSTRACT® technology essentially as described in U.S. Pat. No. 6,265,150, in WO 98/15833, and in “Phage display, A Laboratory Manual” by T. Kuhlman, 2001 (which are incorporated by reference herein). Furthermore, the methods and helper phages as described in WO 02/103012 (which is incorporated by reference herein) were used in the present invention.
Selections of specific binders were performed with hemagglutinin (HA) of influenza A (H1 A/California/07/2009, H1 A/New Caledonia/20/1999, H2 A/Japan/305/1957, H3 A/Brisbane/10/2007, H7 A/Netherlands/219/2003) and/or influenza B (Victoria clade B/Brisbane/60/2008, Yamagata clade B/Florida/04/2006) as target protein. The target protein source was either insect cell produced recombinant protein (Protein Sciences, Connecticut, USA) or HA expressed on the surface of influenza infected and fixed (3% paraformaldehyde) MDCK cells. Various selection conditions were used and are summarized in Table 3. “SD” refers to single domain antibody. If not mentioned otherwise, selections were performed at pH 7.4 and with 5 μg/ml HA protein. CR8033 and CR8071 are monoclonal antibodies (IgG) binding to the head and neck of influenza B HA (Dreyfus et al. 2012).
For first round selections immunotubes were coated overnight with HA (5.0 μg/mL diluted in PBS) and washed with block buffer (2% non-fat dry milk (ELK) in PBS). Aliquots (5-10 μL) of the phage display libraries were blocked in 2 mL blocking buffer (5% non-heat inactivated fetal bovine serum (FBS), 1% mouse serum, and 2% ELK in PBS) and added to the immunotubes. After 2 h incubation at room temperature (RT) tubes were washed (5 to 15 times with 0.05% Tween-20 in PBS and 3 to 5 times with PBS). Bound phages were eluted for 10 min with triethylamine (100 mM) and the pH adjusted to 7.5. E. coli XL1-Blue were infected with eluted phages, plated, and incubation over night at 37° C. Colonies were counted (between 1E+04 and 1E+06 CFU) and scraped from the plates to prepare an enriched phage library (as described in WO 02/103012).
Second round selections were carried out using the phages rescued from the first round and followed essentially the same protocol with the exception of altered antigens, pH and or the addition of epitope blocking monoclonal antibodies. Variant panning strategies were applied with the aim to select strong binders specifically targeting the conserved stem region of HA. To select for cross-reactive single domain clones, also lower amounts of different HA antigens, compared to the first round selection were used. A low pH wash step was introduced in the protocol to increase the chance for selecting phages that can bind to the stem and block the conformational change of HA occurring at pH 5.0 (Brandenburg et al. 2013). Hereto the HA coated immunotubes were incubated for 10 min with 5 times diluted Tryple Select (recombinant trypsin; Invitrogen) to cleave the coated HA0 (into HA1-HA2) followed by washing and blocking steps. After incubation with the phages, the tubes were washed as described earlier, followed by 20 minutes incubation in citric acid sodium phosphate buffer at pH 5.1. After three PBS wash steps phage elution continued as described above. The addition of IgG1 antibodies (10 μg/mL) during selections blocks immune dominant epitopes at the head or neck of HA and can also increases the chance for selecting single domain phages binding to stem of HA. Antibodies CR8033 and CR8071 (Dreyfus et al. 2012) were added during blocking of HA coated immunotubes and during incubation with the phage libraries.
Two or three consecutive rounds of selections were performed before isolation of individual sdAbs. Each selection output was sequence analysed for enrichment factor and the best selections were chosen for further analysis. Individual E. coli colonies were picked to prepare periplasmic extracts containing crude monoclonal sdAbs. In brief, eluted phages were used to infect E. coli strain SF110′ cultures (2YT medium, 10 μg/mL tetracycline, 4% glucose), individual colonies where picked and grown in 96 deep well plates (1 mL 2YT-ATG medium). VHH domain expression was induced by adding IPTG (1 mM). Periplasmic extracts were prepared by dissolving bacteria pellets in 150 μL TES-buffer (100 mM Tris-HCl, 1 mM EDTA, 500 mM sucrose, pH 8.0) for 30 min on ice. The osmotic shock releases the periplasmic fraction and the cleared and sterile filtered sdAb containing supernatant was used for functional screening (see Example 4).
SdAbs from small scale productions (1 mL in 96 deep well plates) were purified and concentrated by using Ni-NTA 96-well spin plates according to manufacturer's instructions.
In parallel to periplasmic extract generations the remaining culture of individual clones were used to create glycerol stocks and to isolate plasmid DNA for sequencing of VHH genes. Unique sequences were further tested.
Cross-selections using HA proteins from influenza group 1, group 2 or B, as well as stringent wash steps at low pH allowed for the isolation of broadly HA binding phages. Periplasmic extractions of small scale E. coli productions resulted in reproducible protein levels suitable for functional screening.
SdAb containing periplasmic extracts were analyzed in a virus neutralization assay (VNA) for their ability to prevent influenza virus infection of mammalian cells. For this purpose, MDCK cells (ATCC, cat # CCL-34) were seeded in 96-well plates (4E+04 cells/well) and 4 h later incubated with a mixture of influenza virus (100 TCID50/well) and sterile filtered periplasmic extract (15 μL/well or dilutions thereof). After 3 days of incubation at 37° C. and 10% CO2, the amount of newly produced virus in the cell culture supernatant was assessed by hemagglutination of 1% turkey red blood cells (TRBC) in V-bottom plates (neutralizing sdAbs reduce viral load in the supernatant resulting in prevention of hemagglutination of TRBC). Since the sdAb input concentration is unknown for the periplasmic extracts, samples were only scored positive or negative for viral neutralization. Multiple influenza strains were tested in parallel to select preferably broad neutralizing sdAbs (see Table 3a).
In conclusion, functional screening resulted in sdAbs which can be classified as neutralizing A group 1, A group 2, A group 1 and 2, or influenza B viruses.
Relevant sdAb sequences were cloned into a standard eukaryotic expression vector suitable for use in Expi293 suspension cells. Production runs were performed for 5-6 days. Expressed sdAbs are secreted in cell culture media. Before complete depletion of glucose from the medium, the culture supernatant was harvested, centrifuged, and sterile filtered. SdAbs were purified using an anti-His resin containing nickel ions (cOmplete HIS-Tag column; Roche, cat #06781543001) and eluted using a high concentration of Imidazole (300 mM). The eluate was buffer exchanged to its final formulation buffer (20 mM NaAc, 75 mM NaCl, 5% Sucrose pH5.5) using a desalting column (HiPrep 26/10 desalting column, GEHC cat #17-5087) and concentrated using Amicon Ultra 3K spin filter (Millipore, cat # UFC900324). After concentration determination, pure sdAbs aliquots were further characterization by SDS-PAGE, HPSEC, SEC-MALS and endotoxin determination. A minimum yield of 5 mg of purified sdAb out of a transfection volume of 600 mL was obtained for all constructs. Only sdAb batches with more than 95% monomeric content and correct molecular mass where used for further characterization.
For selected applications sdAbs without tags (e.g. HIS-tag) were desired. Non-tagged sdAbs were purified via multi-step Ion Exchange Chromatography (IEX). The cleared and filtered supernatant was diluted two-fold in dH2O to lower the conductivity, the pH set to 8.0, and the sample was loaded onto a positively charged Capto Q Impress resin (GEHC, cat #17-5470-02). Non-charged sdAbs remained in the flow through which was then adjusted to pH 3.5. Now positively charged sdAbs were captured on a negatively charged HiTrap Capto SP ImpRes column (GEHC, cat #17-5468-55) and eluted using a high concentration of sodium chloride. The pI of a sdAb can vary greatly and this method was used for molecules with a negative to +1.0 charge at pH 8 and at least a charge of more than +10 in the range of pH 3 to 5. Eluted sdAbs were further treated as described above.
As shown herein, Expi293 cell expression and purification strategies based on HIS-tag and on ion-exchange for tag-less constructs yielded high quantity and quality of monomeric sdAb constructs.
Breadth of Influenza Virus Neutralization
Neutralizing titers of purified sdAbs were assessed by testing a range of concentrations on a large panel of influenza virus strains using the virus neutralization assay as described in Example 4. Titers are reported in Table 4-7. Based on their activity, sdAbs can be divided in influenza A group 1 (encompassing of H1, H5, H2, H6, H11, H9, H8, and H12 viruses) neutralizing molecules, influenza A group 2 (encompassing of H3, H4, H14, H7, and H10 viruses) neutralizing molecules, and influenza B (encompassing Yamagata, Victoria, and Predecessor/Old viruses) neutralizing molecules. Interestingly, some of the sdAbs were capable of neutralizing influenza A viruses from both group 1 and group 2 (Table 6).
Breadth of Binding to HA
The biolayer interferometry platform Octet Red384 (Forté Bio, Pall) was used for label free real time binding analysis of protein—protein interactions in a fast dip and read method on the surface of specific sensors. The shift in detected mass at the tip of a functionalized sensor allowed for studying the binding of sdAbs to recombinant HA. When done over a range of concentrations, not only a general binding but also the KD of sdAbs was determined.
Purified sdAbs with a C-terminal HIS tag were capture on an anti-His sensor (loading phase, Anti-Penta-His sensors, Forté Bio, cat #18-0020). Subsequently the sdAb loaded sensors was incubated with different HA subtypes (20 μg/mL) to test for binding (association phase). The last step of the assay is incubating the sensors in kinetic buffer to determine the dissociation rate of the HA-sdAb complex. Binding capabilities of tested sdAbs are listed in Table 8. Often, sdAbs bind HAs of more strains than they are able to neutralize. The broader binding spectrum is related to their individual affinity for HA (see also Table 9 with KD values).
Label free biolayer interferometry was also used to determine the equilibrium dissociation constants (KD values) as measure of the binding potencies between the sdAbs and recombinant HA molecules of different Influenza strains. The KD values were determined by fitting the binding responses of a sdAb concentration range at steady state (average binding response of the last 10 seconds measured at the plateau in association phase) to obtain the concentration at 50% of the saturation, which reflects the KD value (R=Rmax*[sdAb]/(KD+[sdAb])). Serial dilutions were measured in duplicate and geometric mean KD values are reported in Table 9.
Competition of Single Domain Antibodies with Other HA Binders
Binding competition studies were designed to screen sdAbs for competition amongst themselves and against other HA binding proteins, including well characterized monoclonal antibodies (IgG) with known epitopes on HA. If competition was observed it is assumed that both molecules bind to a similar or at least overlapping epitope at the surface of HA.
Hereto an AlphaLISA competition assay (Perkin Elmer) was established which relied on biotinylated HA (Protein Sciences, 10 μL, 0.5 nM final concentration in 50 μL) bound by IgGs or His-tagged sdAbs (Perkin Elmer, 10 μL, 0.3 nM final concentration in 50 μL). The interaction between HA and the binder was detected after 1 h incubation at RT with two beads, a streptavidin donor bead recognizing HA (10 μL of 10 μg/mL) and an anti Fc or anti His acceptor bead (10 μg/mL) recognizing either the IgGs or sdAbs used. If after an additional hour of incubation the excited donor bead (680 nm) and acceptor bead are in close proximity, an energy transfer (singlet oxygen) can be measured as a luminescence signal of the acceptor bead. The signal intensity in this homogeneous assay format is directly proportional to the binding strength (affinity/avidity) between both binding partners. A competitor, depending on its affinity and concentration (usually tested in a range from 100 nM to 0.5 pM) can disrupt the AlphaLISA signal leading to a sigmoidal inhibitor curve which is fitted with a standard four parameter logistic nonlinear regression model in SPSS. Averages of calculated pIC50 values are shown in Table 10 and 11.
Table 10 and 11 show the average of AlphaLISA pIC50 values (negative log of half maximal inhibitory concentration, higher values indicate exponentially greater potency). ‘H1_Cal_HA’ refers to H1N1 A/California/07/2009, ‘H1_NCa_HA’ refers to HA of H1N1 A/New Caledonia/20/1999, ‘H5_Vie_HA’ refers to HA of H5N1 A/Vietnam/1203/2004, ‘H3_Bri_HA’ refers to HA of H3N2 A/Brisbane/10/2007, ‘H3_Wis_HA’ refers to HA of A/Wisconsin/67/2005, ‘H7_Net_HA’ refers to the HA of H7N7 A/Netherlands/219/2003; B_Bri_HA’ refers to HA of B/Brisbane/60/2008; ‘B_Flo_HA’ refers to HA of B/Florida/04/2006 ‘CR8033’, ‘CR8071’ and ‘CR9114’ are HA binding IgGs characterized by Dreyfus et al. 2012. ‘2D1’ refers to an IgG binding to the receptor binding site of HA characterized by Xu et al. (2010). ‘CR8020’ is an IgG binding to the stem of HA characterized by Ekiert et al. (2011). ‘39.29’ is an IgG binding to the stem of HA characterized in WO2014078268. All SDxxxx possess a His tag used for detection except for indicated ‘tagless’ versions. Empty cells mean ‘not tested’.
Block of Receptor Binding—Hemagglutination Inhibition
The hemagglutination inhibition assay, a common variation of the HA assay, was used to test sdAbs for the ability to bind near the top of the HA head-region and physically block the interaction with sialic acid receptors on target cells, here red blood cells. If an sdAb at sufficient concentration blocks the interaction with sialic acid then “agglutination” (red blood cells clumping together) is inhibited. A serial dilution of sdAbs was prepared in PBS (25 μL/well) and 25 μL of 8 HAU/50 μL virus dilution was added and mixed. After incubation for 1 h at 37° C., 50 μL of 1% turkey red blood cells (TRBC) were added and mixed. After incubation for 30 to 60 min at RT the agglutination pattern is scored visually (tear formation). Besides quadruplicate samples and positive control antibodies, a back titration of the input virus is taken along. The hemagglutination inhibition titer, the minimal concentration at which all interaction of virus with sialic acid receptors on TRBC is blocked was calculated using the Spearman-Karber formula.
The results are shown in Table 12. All influenza A binding sdAbs were negative (i.e. having HI titers>50 μg/mL).
In conjunction with its binding and neutralization profile, SD1084 was shown to be a potent HA head binder and prevents the binding to sialic acid receptors.
Inhibition of Conformational Change of HA by Stem Binding sdAbs
To prove that stem binding sdAbs, similarly to the antibodies they compete with, prevent the conformational change of HA and thereby block viral fusion and subsequent infection, an assay has been developed which measures the presents of the HA head (HA1) after low pH treatment and reduction of the connecting disulfide bridge between HA1 and HA2 (Brandenburg et al. 2013).
The conformational change assay is based on label-free detection and performed using the biolayer interferometry platform Octet Red384 (Forté Bio, Pall). First a batch of C-terminally biotinylated recombinant HA is cleaved (250 μg of HA incubated with 10 μL 0.05% Trypsin-EDTA for 20 min at 37° C. then 30 μL DTI are added to stop the Trypsin activity). The HA (2 μg/mL) is then captured on streptavidin sensors (Forté Bio, cat #18-5020) in the Octet subsequently incubated with the binding partner (sdAbs, positive and negative control antibodies at up to 50 nM). After this incubation step, the sensors will be exposed to a pH range (pH6.5 to 5.0 in 0.2 pH steps). If the binding partner does not stabilize and arrest HA it will undergo conformational change; the HA1 head domain moves away while the HA2 domain, encompassing the fusion machinery, refolds and protrudes the fusion peptide outwards. HA1 will now only be connected to HA2 via a disulfide bridge that can be reduced by DTT exposure in the final assay step (50 mM DTT in PBS). HA1 will then dissociate from the biotinylated HA2 domain, resulting in the detection of a significant loss of mass on the detector. Results are summarized in Table 13.
The results show that the HA stem binding sdAbs are capable of preventing the conformational change of HA according to their neutralization profile. This ability requires the sdAb to stay bound at low pH similar to the conditions in late endosomes. The level of block of the conformational change is positively correlated with their neutralization titer on the respective influenza strains.
Single Domain Antibody Sequences
The sequences of selected and characterized sdAbs according to the invention are listed in Table 14. The sequences of the CDR regions are listed in Table 14a.
In conclusion, virus neutralization assays performed with purified, monomeric sdAb constructs confirmed the four different classes of sdAbs: influenza A group 1, A group 2, A group 1 and group 2, or influenza B neutralizing sdAbs. Nevertheless, binding studies indicate that many A group 1 or A group 2 neutralizing sdAb can also bind HA belonging to the group they fail to neutralize. This results in a significantly larger number of A group 1 and A group 2 binding sdAbs. SdAb which can neutralize or at least bind influenza A and B where not found. SdAbs capable of broadly binding and neutralizing where selected for further characterization (including SD1038, SD1036, SD1083, and SD1084). Determination of the affinity towards HA shows a positive correlation between binding strength and neutralization titer of selected sdAbs. Epitope mapping via competition assays with known HA binding molecules revealed that all but SD1084 bind to the conserved stem of HA. The concentration at which the competition occurred is positively correlated with the neutralization titer meaning that stronger binding and competition results in lower neutralization titers. SD1084 on the other hand binds near or at the sialic acid binding site of the HA head, as demonstrated in the hemagglutination inhibition assay, and can prevent the cellular entry of influenza virus by blocking the receptor binding. All other selected sdAbs can bind HA1 and HA2 in the stem of HA and prevent the conformational change of HA during the fusion process as demonstrated in the conformational change assay.
Generation of sdAb Homo- and Heterodimers
For the creation of sdAb homo- and heterodimers the sdAb coding sequences were either cloned together or the full-length gene was directly synthesized (Genscript) and ligated into the eukaryotic expression vector. In the sdAb dimer constructs the C-terminus of the first sdAb (front) was linked to the N-terminus of the second sdAb (back). The linker sequences of different length (10, 15, 35, and 57 amino acids) consist of amino acids glycine (G) and serine (S). When cloned together, a restriction site (NotI) directly following the first sdAb results in three additional alanine (A) residues. Linker sequences are shown in Table 15 and complete amino acid sequences of the sdAb dimers are shown in Table 16 (influenza A targeting constructs) and in Table 17 (influenza B targeting constructs). The position of sdAbs (front or back) was varied in constructs to allow for the most optimal combination. Expression and purification were performed as described in Example 5.
Influenza Neutralization by sdAb Homo- and Heterodimers
Purified sdAb homo- and heterodimers were tested in influenza virus neutralization assays as described in Example 6 and showed improved potency and breadth when compared to sdAb building blocks. Results are shown for influenza A neutralizing dimers in Table 18 and for influenza B neutralizing dimers in Table 19.
HA Binding of sdAb Homo- and Heterodimers
Purified sdAb homo- and heterodimers were tested in binding assays as described in Example 6 and showed improved binding strength (avidity) when compared to sdAb building blocks. Results are shown for influenza A neutralizing dimers in Table 20.
Generation of sdAb Multimers
For the creation of sdAb multimers (trimers, tetramers and pentamers) the sdAb coding sequences were either cloned together or the full-length gene was directly synthesized (Genscript) and ligated into the eukaryotic expression vector. The linker sequences of different length (10 or 35 amino acids) consist of amino acids glycine (G) and serine (S). When cloned together, a restriction site (Not) directly following the first sdAb results in three additional alanine (A) amino acids and 2 consecutive restriction sites (PacI and XhoI) directly following the second sdAb results in five additional amino acids (LINLE). Linker sequences are shown in Table 15 and complete amino acid sequences of sdAb trimers are shown in Table 23 and of sdAb tetramers and pentamers in Table 24. The position of sdAbs within constructs was varied to allow for the most optimal combination. Expression and purification were performed as described in Example 5.
Influenza Neutralization by Multi-Domain Antibodies
Purified multi-domain antibodies were tested in influenza virus neutralization assays as described in Example 6 and showed improved potency and breadth when compared to sdAb building blocks. Results are shown for influenza neutralizing trimers in Table 25 and for tetramers and pentamers in Table 26.
Multi-Domain Antibody Binding to HA
Label free biolayer interferometry was also used to determine the equilibrium dissociation constants (KD values) as measure of the binding potencies between the multi-domain antibodies and recombinant HA molecules of different Influenza strains at pH 7.4. The KD values were determined by fitting the binding responses of a MD concentration range at steady state (average binding response of the last 10 seconds measured in the plateau of the association phase) to obtain the concentration at 50% of the saturation, which reflects the KD value (R=Rmax*[sdAb]/(KD+[sdAb])). Serial dilutions were measured in duplicate and geometric mean KD values are reported in Table 27.
Inhibition of Conformational Change of HA by Stem Binding sdAbs
To prove that multi-domain antibodies containing HA stem binding sdAb building blocks, similarly to the antibodies they compete with, prevent the conformational change of HA and thereby block viral fusion and subsequent infection, an assay was performed as described in Example 6. Results are summarized in Table 29.
Linking 3 or more sdAbs together can significantly improve potency and breadth of neutralization compared to the individual building blocks. Thus, influenza strains which could not be neutralized by any of the sdAbs individually can reliably be neutralized by multimeric constructs of the same sdAbs. The combination of sdAbs neutralizing influenza A group 1, A group 2, or B resulted in multi-domains capable of neutralizing virtually all tested strains. The increase in breadth of neutralization is related to the underlying breadth of binding of used sdAbs. The increase in avidity for HA in addition to possible other neutralization mechanisms related to the bivalent nature of the constructs are thought to be responsible for the described improvements. Blocking of viral fusion as the mechanism of viral neutralization was confirmed for tested dimers and multi-domains.
Generation of Fc-Fusion Constructs
SdAbs and sdAb multimers can be fused to the Fc region of antibodies. The Fc region is defined as part of an antibody, e.g. a human IgG1 molecule, containing the hinge region followed by the CH2 and CH3 domain. Different Fc fusion constructs have been generated and compared with sdAb multimers and monoclonal antibodies with regard to HA binding, in vitro neutralization and in vivo efficacy.
SdAbs or sdAb multimers were fused with or without additional linkers as shown in Table 15 to the C- and/or N-terminus of Fc fragments. The Fc-fusion constructs were expressed in mammalian cells and secreted into the medium as dimeric Fc molecules. Complete amino acid sequences of the Fc fusion constructs are shown in Table 30. The position of the sdAbs or sdAb multimers within constructs was varied to allow for the most optimal combination. Homodimeric as well as heterodimeric Fc-fusion molecules were generated. Heterodimeric Fc fusions were generated by introducing single point mutations in the CH3 domain as described by Labrijn et al. (2013). These mutations are K409R and F405L and the Fc chains containing these mutations are, respectively, referred to as FcGa and FcGb.
Fc-fusion constructs were expressed in suspension Expi293 cells. DNA constructs containing the sequences for heterodimeric Fc constructs with the K409R or F405L mutations were transfected as single vector containing the two sequential open reading frames. Transient transfection and expression were performed according to the supplier's instructions and were similar to previously reported conditions for the production of human IgG constructs (Dreyfus et al., 2012). Possible aggregates and impurities were removed by preparative gel filtration (Superdex 75 μg or Superdex 200 μg column, GE Healthcare). Samples were analyzed on SDS-PAGE and fractions corresponding to the expected molecular weight were pooled and concentrated using Amicon Ultra 30K centrifugal filters. All production runs resulted in dimeric Fc fusion molecules that were stably linked by disulfide bridges in the hinge region. In case both FcGa and FcGb were transfected into the same cells the purified Fc fusion protein was subjected to controlled reducing conditions in vitro that separates the Fc-fusion into half-molecules and allow reassembly and reoxidation to form a pure heterodimeric Fc fusion molecule as described by Labrijn et al. (2013).
Influenza Neutralization by Fc-Containing Multi-Domain Antibodies
Purified Fc-containing single- and multi-domain antibody constructs were tested in influenza virus neutralization assays as described in Example 6 and showed improved potency and breadth when compared to sdAb building blocks. Results are shown for influenza neutralizing Fc fusion constructs in Tables 31-37.
Functional Fc-Receptor Binding (Antibody Dependent Cellular Cytotoxicity)
Functional binding to cell expressed human FcγRIIIa (CD16a) was measured using an ADCC (antibody dependent cellular cytotoxicity) Reporter Bioassay (Promega). Target A549 cells were infected with B/Brisbane/60/2008 or B/Florida/04/2006, or transfected with a plasmid encoding H3N2 A/Wisconsin/67/2005 HA using Lipofectamine 2000 (Invitrogen) in OPTI-MEM I (Gibco). After 24 hours, HA expressing target cells were seeded into white 96-wells plates and incubated for 30 min with serial dilutions of Fc fusion constructs or IgG control antibodies. As additional negative controls constructs bearing the LALA point mutations in the Fc-fragment were used. The LALA point mutations (L234A, L235A as described by Hessel et al. 2007) show significantly reduced binding to human Fcγ receptors and induction of ADCC. Last, Jurkat effector T-cells (stably expressing FcγRIIIa V158 and NFAT-RE Luciferase) were added to the target cells and incubated for 6 h. Bio-Glo Luciferase Assay Substrate solution (Promega) was added to the wells and luminescence (in RLUs) was measured with a luminescence plate reader (Perkin Elmer). RLU data were fitted using a standard four parameter logistic nonlinear regression model in SPSS.
All SD/MD Fc-fusion constructs (except for the LALA versions) show robust induction of ADCC indicating that binding to the stem epitopes on influenza HA at the surface of cells allows for productive interaction with FcγRIIIa receptor expressing cells. Results are summarized in Table 38.
Fusing sdAbs or sdAb multimers to the Fc fragment of human IgG1 results in HA binding molecules which preserve the potency and breadth of neutralization of the used individual sdAb or multi-domain building blocks. The sdAb building blocks can be fused to the N- as well as the C-terminus of the Fc fragment. During expression two Fc chains form a bivalent antibody-like molecule. It is therefore also possible to express in the same cell two different Fc chain constructs varying in their sdAb or multi-domain part and to create a bispecific antibody-like molecule. Homodimeric and heterodimeric Fc fusion constructs with sdAb and/or multi-domains attached to the N- and/or C-terminus of the Fc fragment have been successfully created and their breadth in neutralization spanning influenza A and B demonstrated. In addition to direct neutralization by the sdAb or multi-domain part, the Fc part of the fusion construct, when bound to HA at the surface of infected or transfected cells, can promote productive interaction with FcγRIIIa (CD16a) receptors at the surface of effector cells. This can in vivo lead to activation of NK cells and subsequent to induction of ADCC. Next to the induction of effector functions the Fc portion can also interact with neonatal Fc receptor resulting in prolonged in vivo half-life.
In Vivo Efficacy of Influenza A Group 1 Single Domain Antibodies
The exemplary influenza A group 1 single domain antibodies SD1016, SD1038 and SD1045 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with SD1016, SD1038 or SD1045 at a single dose of 0.5 mg/kg. Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. Administration of both SD1038 and SD1016 resulted in a statistically significant improvement in survival proportion compared to the vehicle control group whereas administration of SD1045 only resulted in an improvement in survival time (see
In Vivo Efficacy of Influenza A Group 2 Single Domain Antibodies
The exemplary influenza A group 2 single domain antibodies SD1036, SD1046 and SD1048 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with SD1046 or SD1048 at a dose of 5 mg/kg or with SD1036 at 2 doses (0.5 mg/kg or 5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Hong Kong/1/1968-MA (H3N2). Survival and body weight were monitored for 21 days after infection. This study shows that intranasal administration of SD1036, SD1046 or SD1048 provides full protection against a lethal challenge of A/Hong Kong/1/1968-MA virus (see
In Vivo Efficacy of Influenza B Single Domain Antibodies
The exemplary influenza B single domain antibodies SD1083 and SD1084 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with SD1084 at a single dose of 5 mg/kg or with SD1083 at 2 doses (0.5 mg/kg or 5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain B/Florida/4/2006. Survival and body weight were monitored for 21 days after infection. This study shows that sdAb SD1084 provide 100% protection against a lethal challenge with B/Florida/4/2006, whereas SD1083 only provides partial protection at the highest dose of 5 mg/kg. The lower dose of SD 1083 only resulted in an improvement in survival time (
In Vivo Efficacy of Influenza A Single and Multi-Domain Antibodies in H1N1 Model
The exemplary influenza A sdAb SD1038 and the exemplary influenza A multi-domain antibodies MD1211 and MD1212 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD1211 or MD1212 at a dose of 1 mg/kg or with SD1038 either alone (0.5 mg/kg) or mixed 1:1 with SD1036 (total dose=1 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. This study shows that intranasal administration of SD1038, MD1211, MD1212 or a 1:1 mixture of SD1038 and SD1036 provides full protection against a lethal challenge of A/Puerto Rico/8/1934-MA virus. The body weight curves indicate that the efficacy of MD1211 and MD1212 is superior to that of the sdAb (mixture) (
In Vivo Efficacy of Influenza A Single and Multi-Domain Antibodies in H3N2 Model
The exemplary influenza A sdAb SD1036 and the exemplary influenza A multi-domain antibodies MD1211 and MD1212 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD1211 or MD1212 at a dose of 5 mg/kg or with SD1036 either alone (2.5 mg/kg) or mixed 1:1 with SD1038 (total dose=5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Hong Kong/1/1968-MA (H3N2). Survival and body weight were monitored for 21 days after infection. This study shows that intranasal administration of SD1036, MD1211, MD1212 or a 1:1 mixture of SD1036 and SD1038 provides full protection against a lethal challenge of A/Hong Kong/1/1968-MA virus. The body weight curves indicate that the efficacy of MD1211 and MD1212 is superior to that of the sdAb (mixture) (
Comparison of In Vivo Efficacy of SD1038 Monomer and Dimer in H3N2 Model
The exemplary influenza A single domain antibody SD1038 and the exemplary influenza A multi-domain antibody MD1212 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with SD1038 or MD1212 at 4 doses (5 mg/kg, 1.7 mg/kg, 0.6 mg/kg or 0.2 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Hong Kong/1/1968-MA (H3N2). Survival and body weight were monitored for 21 days after infection. This study shows that SD1038 only provides partial protection against a lethal challenge of A/Hong Kong/1/1968-MA virus and that the level of protection is dose-dependent. In contrast, dimeric SD1038 (MD1212) provides 100% protection in all 4 dose groups (
In Vivo Efficacy of Influenza B Multi-Domain Antibodies
The exemplary influenza B multi-domain antibodies MD1221, MD1222 and MD1224 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD1221 or MD1224 at a single dose of 5 mg/kg or MD1222 at 2 doses (0.5 mg/kg or 5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain B/Florida/4/2006. Survival and body weight were monitored for 21 days after infection. This study shows that all 3 multi-domain antibodies provide 100% protection against a lethal challenge with B/Florida/4/2006 (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibodies Against H1N1 after i.v. Administration
The exemplary influenza A & B multi-domain antibodies MD1301 and MD2601 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intravenously with MD1301 or MD2601 at a single dose of 3 mg/kg. CR9114 was taken along as positive control. Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. This study shows that the Fc-containing multi-domain antibody MD2601 provides full protection after i.v. administration while Fc-less MD1301 has no effect on survival. Control antibody CR9114 only provides partial protection against a lethal challenge with A/Puerto Rico/8/1934-MA (H1N1) (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibodies Against H1N1 after i.n. Administration
The exemplary influenza A & B multi-domain antibodies MD1301 and MD2601 and reference antibody CR914 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD1301, MD2601 or reference antibody CR9114 at 3 doses (0.2, 0.05 or 0.01 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. This study shows that the minimum effective dose (defined as the lowest dose providing 100% protection) is 0.05 mg/kg for the Fc-containing antibodies MD2601 and CR9114 and 0.2 mg/kg for Fc-less MD1301. Mice receiving 0.05 mg/kg CR9114 showed a larger drop in body weight than mice receiving the same dose of MD2601 (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibody MD2617 Against H1N1
The exemplary multi-domain antibody MD2617 was selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed with MD2617 either intranasally at 0.2 mg/kg, 0.05 mg/kg or 0.01 mg/kg or intravenously at 3, 1 or 0.3 mg/kg. Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. Administration of MD2617 at a dose 0.2 mg/kg i.n. or 3 mg/kg i.v. resulted in a statistically significant improvement in survival proportion compared to the vehicle control group (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibody MD2617 Against H3N2 and B Florida
The exemplary multi-domain antibody MD2617 was selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed with MD2617 either intranasally at 0.5 mg/kg or intravenously at 2 mg/kg. CR9114 dosed intravenously at 2 mg/kg was taken along as positive control. Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of A/Hong Kong/1/1968-MA (H3N2) or B/Florida/4/2006. Survival and body weight were monitored for 21 days after infection. Intranasal as well as intravenous administration of MD2617 resulted in a statistically significant improvement in survival proportion compared to the vehicle control group.
In Vivo Efficacy of Influenza A & B Multi-Domain Antibodies MD2407 and MD3606 Against B Florida after i.n. Administration
The exemplary multi-domain antibodies MD2407 and MD3606 and reference antibody CR9114 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD2407, MD3606 or CR9114 at 3 doses (0.02 mg/kg, 0.1 mg/kg or 0.5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain B/Florida/4/2006. Survival and body weight were monitored for 21 days after infection. Administration of 0.02, 0.1 and 0.5 mg/kg MD2407 and MD3606 resulted in a statistically significant improvement in survival proportion compared to the vehicle control group whereas administration of CR9114 only resulted in an improvement in survival proportion at 0.1 and 0.5 mg/kg (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibody MD3606 Against B Florida after i.v. Administration
The exemplary multi-domain antibody MD3606 and reference antibody CR9114 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intravenously with MD3606 or CR9114 at 3 doses (0.2 mg/kg, 1 mg/kg or 5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain B/Florida/4/2006. Survival and body weight were monitored for 21 days after infection. This study shows that MD3606 provides full protection against B/Florida/4/2006 down to a dose of 1 mg/kg. In contrast reference antibody CR9114 only provides partial protection at the highest dose of 5 mg/kg (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibodies MD2407 and MD3606 Against H3N2 after i.n. Administration
The exemplary multi-domain antibodies MD2407, MD3606 and reference antibody CR9114 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD2407, MD3606 and CR9114 at 3 doses (0.02 mg/kg, 0.1 mg/kg or 0.5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Hong Kong/1/1968-MA (H3N2). Survival and body weight were monitored for 21 days after infection. This study shows that MD2407 and CR9114 provide full protection against A/Hong Kong/1/1968-MA down to a dose of, respectively, 0.1 and 0.5 mg/kg. MD3606 provides full protection even at the lowest dose of 0.02 mg/kg (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibody MD3606 Against H3N2 after i.v. Administration
The exemplary multi-domain antibody MD3606 and reference antibody CR9114 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intravenously with MD3606 or CR9114 at 3 doses (0.6 mg/kg, 1.7 mg/kg or 5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Hong Kong/1/1968-MA (H3N2). Survival and body weight were monitored for 21 days after infection. Administration of MD3606 and CR9114 down to a dose 1.7 mg/kg resulted in a statistically significant improvement in survival proportion compared to the vehicle control group. Mice treated with 5 or 1.7 mg/kg MD3606 showed a smaller drop in body weight than mice treated with the same doses of CR9114 (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibodies MD2407 and MD3606 Against H1N1 after i.n. Administration
The exemplary multi-antibodies MD2407, MD3606 and reference antibody CR9114 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intranasally with MD2407, MD3606 or CR9114 at 3 doses (0.02 mg/kg, 0.1 mg/kg or 0.5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. Administration of 0.25 and 0.05 mg/kg MD2407 or CR9114 resulted in a statistically significant improvement in survival proportion compared to the vehicle control group, while for MD3606 this improvement was significant down to the lowest dose of 0.01 mg/kg (
In Vivo Efficacy of Influenza A & B Multi-Domain Antibody MD3606 Against H1N1 after i.v. Administration
The exemplary multi-domain antibody MD3606 and reference antibody CR9114 were selected for in vivo influenza neutralization studies using Balb/C mice. Briefly, 6-8 week old female Balb/C mice (n=8) were dosed intravenously with MD3606 or CR9114 at 3 doses (0.6 mg/kg, 1.7 mg/kg or 5 mg/kg). Another group of 8 mice receiving buffer solution only served as a vehicle control group. One day post-administration mice were challenged intranasally with 25×LD50 of influenza strain A/Puerto Rico/8/1934-MA (H1N1). Survival and body weight were monitored for 21 days after infection. Administration of 1.7 and 5 mg/kg MD3606 and 5 mg/kg CR9114 resulted in a statistically significant improvement in survival proportion compared to the vehicle control group (
Protein sequences of sdAbs SD1036, SD1038, SD1046, SD1083, SD1084 and SD1087 were blasted against the IMGT human V genes database (http://www.imgt.org). Each sdAb was subsequently aligned with the most homologous human V gene sequence. The FR4 sequence of each sdAb was aligned with the human J consensus sequence WGQGTLVTVSS. Amino acid differences in the sdAb framework regions (FRs) relative to the aligned human V and J sequences are indicated in table 39.
Subsequently multiple series of sdAb variants were made in which different combinations of non-human FR residues were replaced by their human equivalents. Residues 37, 44, 45 and 47 in FR2 and 103 in FR4 were retained in all variants. Two Met residues, one located in CDR2 of SD1087 and the other in CDR3 of SD1038 were also mutated with the aim to remove a potential Met oxidation site. Amino acid sequences of all variants of sdAbs SD1036, SD1038, SD1046, SD1083, SD1084 and SD1087 are listed in table 40. Humanized sdAb variants were analyzed for temperature stability, expression level (in HEK293 cells) and in vitro neutralizing activity. Temperature stability was assessed for selected sdAbs by measuring their melting temperatures using DSC. In vitro neutralizing activity was determined in a standard 3-day VNA using MDCK cells and ˜100 TCID50 of influenza virus. IC50 values, melting temperatures and expression levels are listed in Tables 41-43. The number of amino acid differences in the sdAb framework regions (FRs) relative to the aligned human V and J sequences as well as the calculated % FR identity are also listed.
Humanization of SD1036:
For SD1036 11 humanized variants were made. Several of these variants showed equal or in some cases even better neutralizing activity than the parent sdAb. No major differences in expression levels were observed, whereas for the majority of SD1036 variants the onset temperature of melting was increased. Variant SD3097 was selected as final humanized variant because it has the lowest number of FR mutations vs human germline, a high Tm onset value and in addition shows potent neutralization of all group 2 influenza strains tested.
Humanization of SD1038:
For SD1038 21 humanized variants were made. All variants, except SD3031-33, showed similar neutralizing activity against 4 group 1 strains as the parent sdAb. IC50 values for H3 strains A/Brisbane/10/07 and A/Hong Kong/1/68 were slightly higher for most of the SD1038 variants. Variant SD3119 was selected as final humanized variant because it has the lowest number of FR mutations vs human germline, a high Tm onset value and shows potent neutralization of all influenza strains tested. In this variant Met in CDR3 is replaced by Ile.
Humanization of SD1046:
For SD1046 11 humanized variants were made. A first series of variants showed strongly reduced neutralizing activity compared to the parent sdAb. A second series of variants was made which showed very similar activity as SD1046 in VNA. Of these variants, SD3099 was selected as final humanized variant because it has the lowest number of FR mutations vs human germline and shows high temperature stability.
Humanization of SD1083:
For SD1083 10 humanized variants were made. Several of these variants showed low expression levels in HEK293 cells and 2 did not express at all. Of the 3 variants that expressed well, SD3087 was selected as final humanized variant. This sdAb is more potent than the parent SD1083 in VNA and has a substantially higher Tm onset value.
Humanization of SD1084:
For SD1084 6 humanized variants were made. Four of these variants showed similar neutralizing activity in VNA as the parent sdAb. Of these variants, SD3085 was selected as final humanized variant because it has the highest Tm onset value and only 2 FR mutations vs human germline.
Humanization of SD1087:
For SD1087 23 humanized variants were made. A first series of 8 variants showed no measurable activity in VNA against 2 influenza B strains. A second series of SDAbs was made which included a number of variants showing similar IC50 values as SD1087. The temperature stability of these variants was lower than that of the parent molecule. None of the variants containing a substitution of Met in CDR2 showed activity in VNA. SD3093 was selected as final humanized variant because it showed only a modest decrease in Tm onset value and its activity in VNA was equal to that of SD1087.
Generation of Fc Fusion Constructs
The humanized sdAb variants described in Example 11 were used to generate multimeric Fc fusion constructs. The humanized multimeric binding molecules, i.e. multimeric binding molecules comprising at least two humanized sdAbs, were fused directly to the N-terminus of the Fc region. The Fc-fusion constructs were expressed in mammalian cells and secreted into the medium as dimeric Fc molecules. Complete amino acid sequences of the Fc fusion constructs are shown in Table 44. Homodimeric as well as heterodimeric Fc-fusion molecules were generated. Heterodimeric Fc fusions were generated by introducing single point mutations (K409R and F405L) in the CH3 domain of the 2 Fc chains as described by Labrijn et al. (2013) or by introducing the knobs-into-holes mutations as described in EP0812357B1 and EP0979281B1.
Gene constructs encoding humanized sdAb multimer Fc fusion proteins were codon optimized for mammalian cell expression and incorporated into Lonza pEE12.4 vectors. The expression vectors (that utilize the CD4 HC signal peptide) were amplified, purified, and concentrated to a final concentration of >5 mg/mL in sterile water for transfection of CHO cell lines using electroporation. Heterodimeric Fc fusion proteins were produced by co-transfection of equal amounts of vectors encoding the 2 individual chains. Homodimeric Fc fusions were produced using a single vector construct as noted above. The cell cultures were grown using standard suspension phase shake flask procedures. The filtered culture supernatants were applied to HiTrap MabSelect SuRe columns, washed with PBS, eluted with 0.1M sodium acetate pH 3.5, neutralized using 2.5M Tris pH 7.2, and dialyzed into dPBS.
Influenza Neutralization by Humanized sdAb Multimer Fc Fusion Proteins
Purified Fc fusion proteins were tested in influenza virus neutralization assays as described in Example 6 and showed similar potency and breadth when compared to the corresponding wild-type versions. Average neutralization titers for different influenza strains are summarized in Table 45.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15153957 | Feb 2015 | EP | regional |
This application is continuation of U.S. application Ser. No. 15/548,843, filed Aug. 4, 2017, which is a Section 371 of International Application No. PCT/EP2016/052556, filed Feb. 5, 2016, which was published in the English language on Aug. 11, 2016 under International Publication No. WO 2016/124768 A1, claiming priority under 35 U.S.C. § 119(b) to European Patent Application EP 15153957.4, filed Feb. 2, 2015, and the disclosures of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8961978 | Kwaks et al. | Feb 2015 | B2 |
| 10370435 | Brandenburg | Aug 2019 | B2 |
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| 2009121004 | Oct 2009 | WO |
| 2009147248 | Dec 2009 | WO |
| 2013007770 | Jan 2013 | WO |
| 2013011347 | Jan 2013 | WO |
| 2013030604 | Mar 2013 | WO |
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| Number | Date | Country | |
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| 20190359693 A1 | Nov 2019 | US |
| Number | Date | Country | |
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| Parent | 15548843 | US | |
| Child | 16455151 | US |
