Patent Application
20230119254
The invention is in the field of treatment of conditions characterized by unwanted thrombosis, such as heart attack, stroke, and complications of surgery where bleeding should be minimized. In particular it is directed to administering factors that bind phosphatidyl serine on the surface of activated platelets in competition with prothrombinase complex along with an apyrase for prevention or treatment of thrombosis.
The relevant conditions treated by the method of the present invention are both arterial and venous thrombosis.
In the case of arterial thrombosis, a high concentration of unfractionated heparin is routinely used to prevent peri-operative coagulation for patients undergoing coronary artery bypass surgery (CABG). Despite the use of protamine reversal, the heparin treatment increases post-operative bleeding and approximately 30 percent of patients require a blood transfusion after CABG. Other antithrombotic therapy also significantly increases the risk of postoperative bleeding. Clopidogrel (brand name: Plavix), prasugrel (brand name: Effient), ticagrelor (brand name: Brilinta), and ibuprofen are generally discontinued for several days prior to coronary surgery. Patients taking warfarin (brand name: Coumadin), apixaban (brand name: Eliquis), rivaroxaban (brand name: Xarelto), edoxaban (brand name: Savaysa), or dabigatran (brand name: Pradaxa) should stop taking it before surgery. As such, an antithrombotic treatment without causing peri or post-operative bleeding is critically needed.
Current adjunctive antithrombotic therapy during percutaneous coronary intervention (PCI), formerly known as angioplasty with a stent, also increases major bleeding. Coronary artery disease can be diagnosed by the presence of acute ST segment elevation myocardio infarction (STEMI) on an electrocardiogram. Platelets play a central role in thrombotic complication (Heit, J A, J Thromb Haemost (2005) 3:1611-1617). Treatment for this condition is directed to restoring normal coronary blood flow and to maximize salvage of the functional myocardium.
Current US and European guidelines recommend primary PCI along with adjunctive therapy which includes dual-antiplatelet agents plus an anticoagulant. However, the currently available agents with antiplatelet activity are delayed in the onset of action in about 40%-50% of STEMI patients (Riteau, N., et al., Am J Respir Crit Care Med (2010) 182:774-783) and the combinations all have mechanisms of action that increase bleeding. In a recent clinical trial, 11%-12% of patients suffered major bleeding (Ufer, M., Thromb Haemost (2010) 103:572-585). In addition, none of the current antithrombotic agents (i.e., combinations of antiplatelet and anticoagulant agents) protect against reperfusion injury, which is defined as myocardial infarction associated with the restoration of coronary blood flow after ischemia. Reperfusion injury accounts for up to 50% of the final size of a myocardial infarct and causes related cardiac dysfunctions. This may explain why, despite optimal coronary reperfusion, that the rate of death after AMI approaches 10% and the incidence of heart failure is almost 25% (Heit, J A, J Thromb Haemost (2005) 3:1611-1617; Spyropoulos, A C, et al., J Manag Care Pharm (2007) 13:475-486; Marcus, A J, et al., Semin Thromb Hemost (2005) 31:234-246).
Therefore, there is a long felt unmet medical need for fast acting therapeutic agents as adjuncts to PCI that will facilitate reperfusion without increasing bleeding and also attenuate reperfusion injury which will improve myocardial salvage and recovery of left ventricular function thereby reducing the incidence of heart failure.
A left ventricular assist device (LVAD) is a pump that is used for patients who have reached end-stage heart failure. The LVAD is a battery-operated, mechanical pump, and surgically implanted which then helps the left ventricle (main pumping chamber of the heart) pump blood to the rest of the body. LVADs can be used until a heart becomes available or patients can receive long-term treatment using an LVAD, which can prolong and improve patients' lives. Despite significant improvements in survival, functional capacity and quality of life, a common complication is pump thrombosis, stroke, and bleeding. As all the current antithrombotic drugs increase bleeding risk, achieving the optimal antithrombotic therapy that balances thrombosis prevention with increased bleeding has been an ongoing challenge.
For patients on chronic antithrombotic therapy who undergo surgery, current clinical recommendations suggest discontinuation of antithrombotic therapy prior to surgery as these drugs elevate risk for excessive bleeding. For example, stop aspirin around the time of surgery in patients who require CABG; stop unfractionated heparin 4-6 h before surgery in patients, last dose of Low Molecular Weight Heparin 24 h before surgery in patients. However, discontinuation of these antithrombotic treatments also increases the risk for peri-operative thrombosis such as pulmonary embolism, which can be highly fatal. Currently, there is no antithrombotic treatment that can be safely used for peri-operative management.
Similar disadvantages are found with regard to anticoagulant treatment for venous thromboembolism in that the treatment is plagued by increase major bleeding events and offers minimal protection against vein wall thickening or fibrosis. Venous thromboembolism including deep vein thrombosis (DVT) and pulmonary embolism (PE) is a major source of morbidity and mortality worldwide.
The current prophylaxis and treatment of DVT is administration of a parenteral anticoagulant, for example heparin, with subsequent transition to an orally active anticoagulant such as warfarin (Heit, J A, J Thromb Haemost (2005) 3:1611-1617; Kyrle, P A, et al., Lancet (2005) 365:1163-1174). Other agents have also been used—for example, Rivaroxaban has been approved for both short-term and long-term treatment (Perzborn, E., et al., Nature Rev. Drug Discovery (2011) 10:61-75; Ufer, M., Thromb Haemost (2010) 103:572-585), but all have mechanisms of action that produce bleeding which limits the dose that can be administered. In addition, the current treatments do not effectively protect against post-thrombotic syndrome (PTS) which is characterized by blood reflux caused by compromised vein valves, overflow obstruction and tissue hypoxia that is secondary to vein wall thickening and fibrosis (Popuri, R K, et al., Arterioscler Thromb Vasc Biol (2011) 31: 479-484; Saarinen, J., et al., J Cardiovasc Surg (2000) 41:441-446; Deatrick, K B, et al., J Vasc Surg 2011 53:139-146).
The impact of DVT is increasing with the growing aging population. In 2005, the United States Senate designated March as “Deep Vein Thrombosis Awareness Month.” Clearly, the health and economic burden of DVT is profound and DVT patients would benefit greatly from an efficacious antithrombotic agent that is not limited by increased bleeding risk and also is capable of attenuating PTS.
As described below, the compositions and methods of the present invention offer a solution to this unmet medical need as well.
The use of apyrases, in particular soluble CD39L3 and modifications thereof, for treating conditions associated with thrombosis is disclosed in U.S. Pat. Nos. 7,247,300; 7,390,485 and 8,021,866. Use of apyrases as therapy for bleeding conditions is disclosed in U.S. Pat. No. 8,535,622 and an enhanced form of an apyrase based on soluble CD39L3 is disclosed in U.S. Pat. No. 8,771,683. In addition, apyrase therapy for fibroproliferative disorders, pulmonary hypertension and heart failure is disclosed in U.S. Ser. No. 14/666,121, currently pending.
A protein known to bind phosphatidyl serine on the surface of activated platelets in competition with the binding of prothrombinase complex, annexin V, is believed to be associated with a prevention and treatment of thrombosis in view of the showing that antibodies reactive with annexin V effect arterial and/or venous thrombosis, for example, in patients with systemic lupus erythematosus (Esposito, G., et al., Autoimmunity Rev (2005) 4:55-60). Indeed, although the primary use currently of annexin V is as label for apoptosis, it is understood that annexin V inhibits prothrombin activation and is able to prevent thrombus formation under normal venous and arterial blood flow conditions. Antibodies reactive with annexin V have been shown to result in thrombotic complications in patients with type 1 diabetes. (Bakar, F., et al., J Clin Endocrinol Metab (2014) 99:932-937).
It has now been found that annexin V or other annexins that bind phosphatidyl serine on the surface of activated platelets and an apyrase when administered in combination as such, or when administered as a single fusion protein, exert a synergistic antithrombotic effect and do not enhance unwanted bleeding.
Thus, this combination represents a solution to the problems currently associated with treatment of both arterial and venous thrombosis. Certain embodiments of annexin V coupled to an apyrase as a fusion protein have also been found to exhibit favorable properties with respect to recombinant production.
All documents cited herein are incorporated by reference in their entirety.
In one aspect, the invention is directed to a composition which comprises an apyrase and an annexin that binds phosphatidyl serine (PS) on the surface of activated platelets; said apyrase and annexin are administered in amounts that are together effective to inhibit thrombosis without increasing bleeding.
The combination of annexin and an apyrase may also be administered in the form of a single molecule wherein the apyrase and annexin are covalently coupled.
With respect to ease of production of such a covalently coupled combination, it is advantageous that the apyrase and annexin are covalently coupled through a linker peptide to form a fusion protein, especially wherein the linker peptide is resistant to hydrolysis in plasma and/or in cell culture supernatant.
The invention is also directed to recombinant production of the covalently coupled form of apyrase and annexin including the materials associated with such recombinant production and to methods to treat a subject experiencing or at risk for thrombosis using the compositions of the invention.
The invention takes advantage of the unexpectedly synergistic combined action of antiplatelet and anticoagulant proteins, an apyrase and an annexin to prevent or treat both arterial and venous thrombosis. The combination solves problems associated with commercially available antithrombotics, and in particular has a more favorable profile with respect to avoiding enhanced bleeding as compared to these commercial antithrombotics. In addition, the invention includes unique fusion proteins wherein the apyrase and annexin are linked by additional amino acid sequence. When produced as a fusion protein, the invention includes advantageous forms thereof in terms of their expression levels when produced recombinantly and in terms of their resistance to proteolysis both in recombinant culture and in plasma. These features appear dependent on the linker provided between the annexin component and the apyrase component.
In general, any apyrase that inhibits platelet activation and aggregation can be employed. A discussion of such apyrases can be found in U.S. Pat. No. 7,390,485. Certain mutants of soluble forms of CD39L3 are particularly useful.
A particularly useful form of apyrase is the soluble form of CD39L3 the sequence of which is disclosed in U.S. Pat. No. 7,390,485. Full length CD39L3 and its deduced amino acid sequence are SEQ ID NO: 55 and SEQ ID NO: 56, respectively therein. The soluble form is also disclosed in this patent and the sequence of the encoding nucleotides as SEQ ID NO: 59 and of the deduced amino acid sequence as SEQ ID NO: 60 therein.
The '485 patent also describes site directed mutagenesis of both soluble CD39 and soluble CD39L3. Particularly useful in the present invention are mutated forms of soluble CD39L3 wherein the amino acids at positions 67 and 69 are mutated. Two of these mutants of soluble CD39L3 are R67A T69R and R67G T69R. Soluble CD39L3 R67G T69R is a particularly preferred double mutant. An “enhanced” form of this sequence is disclosed in U.S. Pat. No. 8,771,683 and the relevant nucleotide and amino acid sequences are reproduced herein as SEQ ID NOs: 1 and 2 respectively. This embodiment is designated APT102.
The annexin component useful in the invention is annexin V which binds phosphatidyl serine on activated platelets. The annexins are members of a large family of proteins with similar structures, but with various physiological activities. Any annexin that exhibits the above-mentioned property of annexin V may be used in the invention. The structures of these annexins including the native or optimized nucleotides sequences encoding them are known in the art. In some embodiments the annexin chosen will be of the same species as the subject of treatment.
In general, it is convenient to produce the components useful in the invention using recombinant techniques. This is particularly the case for embodiments wherein the apyrase and annexin are linked covalently. Recombinant techniques for such proteins are well known in the art at this time and the recombinant production may be conducted in variety of cells and settings, including animal, plant and microbial cells in culture and as an in situ location in multicellular organisms. The invention therefore includes recombinant materials for production of these components, such as expression systems with suitable control sequences, vectors, host cells harboring these and the like.
The compositions of the present invention may be administered to warm-blooded animals, including humans and other mammals as well as to domestic avian species. These may include companion or farm animals, for example. For treatment of human ailments, a qualified physician will determine how the compositions of the present invention should be utilized with respect to dose, schedule and route of administration using established protocols. A similar role is assumed by a veterinarian in other species. Such applications may also utilize dose escalation.
Preferably, the pharmaceutical compositions of the present invention are administered parenterally, i.e., intraarterially, intravenously, intraperitoneally, subcutaneously, or intramuscularly. More preferably, the pharmaceutical compositions are administered intravenously or intraperitoneally by a bolus or infusional injection.
Pharmaceutical compositions of the invention are prepared according to standard techniques and may comprise water, buffered water, saline, glycine, dextrose, iso-osmotic sucrose solutions and the like, including glycoproteins for enhanced stability, such as albumin, lipoprotein, globulin, and the like. These compositions may be sterilized by conventional, well-known sterilization techniques. The resulting aqueous solutions may be packaged for use or filtered under aseptic conditions and lyophilized, the lyophilized preparation being combined with a sterile aqueous solution prior to administration. The compositions may contain pharmaceutically acceptable auxiliary substances as required to approximate physiological conditions, such as pH adjusting and buffering agents, tonicity adjusting agents and the like, for example, sodium acetate, sodium lactate, sodium chloride, potassium chloride, calcium chloride, and the like.
The concentration of the invention components in the pharmaceutical formulations can vary widely, such as from less than about 0.05%, usually at or at least about 2-5% to as much as 10 to 30% by weight and will be selected primarily by fluid volumes, viscosities, and the like, in accordance with the particular mode of administration selected. For example, the concentration may be increased to lower the fluid load associated with treatment.
Preferably, the pharmaceutical compositions of the present invention are administered intravenously. Dosage for the delivery vehicle formulations will depend on the ratio of drug to lipid and the administrating physician's opinion based on age, weight, and condition of the patient. One preferred protocol comprises a bolus IV administration followed by prolonged IV infusion.
In addition to pharmaceutical compositions, suitable formulations for veterinary use may be prepared and administered in a manner suitable to the subject. Preferred veterinary subjects include mammalian species, for example, non-human primates, dogs, cats, cattle, horses, sheep, and domesticated fowl. Subjects may also include laboratory animals, for example, in particular, rats, rabbits, mice, and guinea pigs.
The compositions of the invention are useful in subjects where thrombosis is to be treated or prevented without engendering excessive bleeding. These include, without limitation, surgery, e.g., thoracic surgery including CABG and major surgery with high thrombotic risk or surgery or medical investigations where anti-thrombotic treatment is administered as prophylaxis against clotting on indwelling catheters or placement of devices (e.g. electrophysiological investigations, pacemaker implantations, percutaneous heart-valve placement or repair). Subjects to be treated with the invention compositions also include subjects with myocardial infarction, including STEMI, undergoing revascularization/reperfusion treatment with PCI or thrombolysis and subjects with stable or unstable coronary artery disease undergoing coronary revascularization with PCI. Suitable subjects are those with peripheral vascular disease undergoing revascularization by peripheral vessel-grafting or intra-luminal balloon angioplasty w/wo stenting, and subjects on chronic anti-thrombotic therapy, including those with atrial fibrillation and under treatment/prophylaxis for venous thromboembolism (VTE), and therefore a high risk of thrombotic complications, as a bridging strategy/peri-operative management during fasting and surgical procedures when subjects cannot sustain oral anti-thrombotic treatment.
The compositions are also useful as a prophylaxis or treatment for VTE—including deep vein thrombosis and pulmonary embolism—including prophylactic treatment related to orthopedic surgery and treatment of fractures, and immobilized subjects, subjects with acute or chronic illness (including cancer) and high risk of thrombosis. In addition the invention compositions are used to treat subjects with heparin induced thrombocytopenia (HIT) and subjects with acute ischemic stroke requiring additional anti-thrombotic treatment added on to standard-of-care, including before, during or after potential reperfusion treatment (but also when reperfusion treatment has not been used) as well as treatment or during pulmonary angioplasty procedures in subjects with chronic thromboembolic pulmonary disease/hypertension (CTEPH).
Stroke is defined as loss of neurological function due to brain ischemia or intracranial hemorrhages, including but may not be limited to, for prevention of tissue destruction and improved neurological function and outcome in conjunction with acute ischemic stroke; large and/or small vessel occlusion ischemic stroke in conjunction with reperfusion by thrombolysis or thrombectomy; embolic stroke; and prevention of recurrent stroke in patients with acute cerebral transitory ischemic attacks with high risk of stroke.
The apyrases and annexin used in the invention compositions may be formulated separately in individual compositions or in the same composition or are covalently bound. Separate compositions can be administered separately to subjects simultaneously or sequentially. Kits that include, in separate containers, a first composition in a first container comprising an apyrase and, in a second container, a second composition comprising a suitable annexin can then be packaged into the kit.
The kit will also include instructions as to the mode of administration of the compositions to a subject, at least including a description of the ratio of amounts of each composition to be administered. In one embodiment, equimolar amounts are administered. However, the molar ratio of apyrase to annexin will depend on the choices for these components and can vary from 10:1 to 1:10 for apyrase:annexin. Alternatively, or in addition, the kit is constructed so that the amounts of compositions in each container is pre-measured so that the contents of one container in combination with the contents of the other represent the correct ratio. Alternatively, or in addition, the containers may be marked with a measuring scale permitting dispensation of appropriate amounts according to the scales visible. The containers may themselves be useable in administration; for example, the kit might contain the appropriate amounts of each composition in separate syringes. Formulations which comprise the pre-formulated correct ratio of therapeutic agents may also be packaged in this way so that the formulation is administered directly from a syringe prepackaged in the kit.
Unless defined otherwise, all terms of art, notations and other scientific terms or terminology used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this invention belongs. In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art. Many of the techniques and procedures described or referenced herein are well understood and commonly employed using conventional methodology by those skilled in the art. As appropriate, procedures involving the use of commercially available kits and reagents are generally carried out in accordance with manufacturer defined protocols and/or parameters unless otherwise noted. All patents, applications, published applications and other publications referred to herein are incorporated by reference in their entirety. If a definition set forth in this section is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications and other publications that are herein incorporated by reference, the definition set forth in this section prevails over the definition that is incorporated herein by reference.
As used herein, “a” or “an” means “at least one” or “one or more.”
The following examples are to illustrate, not limit the invention. Moreover, scientific discussions below of underlying mechanisms gleaned from the data are also not meant as limitations of the inventions described here.
Abbreviations: BT: bleeding time; aPTT: activated partial thromboplastin time; TCT: thrombin clotting time; ACT: activated clotting time; PT: prothrombin time; LMWH: Low molecular weight heparin; FX: Factor X; DVT: deep vein thrombosis; electrical injury model; IVC: inferior vena cava.
The apyrase agent used in these examples is a soluble apyrase agent made from a construct encoding soluble CD39L3 R67G T69R: with homogenized N-terminus as described in U.S. Pat. No. 8,771,683 designated APT102 (SEQ ID NO: 2) herein.
Nucleic acid-encoding annexin V was fused to the C-terminus of the apyrase agent with linkers of various lengths to optimize expression levels and prevent degradation and the various iterations were provided with a sequence encoding the mouse IgG kappa sequence as shown in SEQ ID NOs:3 and 4 herein and inserted into the expression plasmid pSecTag2c.
HEK 293 cells were stably transformed with the linearized expression plasmid that provides for the expression of the apyrase annexin V fusion proteins with variations in linker sequence.
Transformants were adapted to serum-free suspension culture and continually split to larger flasks. A typical suspension culture was inoculated at 0.5×106 cells per mL and in 5 to 6 days HEK 293 cells grew typically over 3.5×106 cells per mL. The cells were split every 3-4 days and fusion proteins in conditioned media were collected. The production of the apyrase annexin V fusion with 20 AA linker was scaled up to 3 L spinner.
The proteins were purified to homogeneity using IMAC, Q and SP columns. The amino acid sequences of various linkers designed is shown below.
For the originally designed linker, m0, approximately 50% of the purified protein was degraded in the linker region by the protease activity present in the culture medium. Further study shows that low pH (e.g. 5.0) accelerated the degradation compared to pH of 7.4. Protease resistant fusion protein was designed by introducing G to T substitution as shown in m1, which was still susceptible to the protease degradation when the pH of the clarified supernatant was reduced to 5 with sodium citrate. When this mutation was combined with the replacement of serine with alanine or glutamine as shown in m2 and m3, degradation was minimized.
It was also shown that a 20 amino acid linker was most advantageous based on comparison of expression levels.
The expression levels were compared with a flexible linkers of 5, 10, 15 and 20 amino acid residues in length or a rigid linker of 9 amino acid residues.
The proteins from clarified supernatants of the conditioned media as described above were separated on SDS polyacrylamide gel electrophoresis. The analysis shows the fusion protein expression was positively correlated with the length of the linkers with 20AA resulting in the highest expression. The rigid linker construct also resulted in a lower expression than the variant with 20AA flexible linker. The amino acid and nucleotide sequences of this 20AA linker are shown in SEQ ID NO:3.
The final construct used in Examples 2-10 has the nucleotide sequence SEQ ID NO: 7 wherein the signal sequence encoded bovine alpha lactalbumin signal peptide. The encoded fusion of apyrase-linker-annexin V is designated APT402.
The apyrase agent in the construct for production of the fusion protein APT402 is APT102. The apyrase annexin V fusion with 20 AA linker described in Example 1 was produced in CHO cells with the signal sequence of the bovine α-lactalbumin signal peptide from a construct shown as SEQ ID NO: 7. As noted, the apyrase-linker-annexin protein was designated as APT402. The production cell lines were made by four rounds of transduction of the CHO parental cell line with retrovector made from the Catalent (Madison, USA) and expression retrovector plasmid. The pooled population of transduced cells was named CHO-S-APT402-R 4X pool. Samples of the pooled population cell lines were cryopreserved.
For 10 L production, cell line CHO-S-APT402-R 4X pool was passaged every 3-4 days during the exponential growth phase for scale-up for the 10 L Braun bioreactors in PFCHO LS (HyClone). Cells were inoculated at a cell density of approximately 300,000-400,000 cells/ml in PFCHO LS (HyClone) medium into two 10 L bioreactors. Fed-batch supplements used for this study were HyClone PS307 (12% (w/v) solutions), AGT CD CHO 5× Feed Medium Complete (Invitrogen), 20% glucose solution, 200 mM L-glutamine, 50× solution of L-Asparagine (15 g/L)/L-Serine (10 g/L), 50× solution of L-Tyrosine (4 g/L)/L-Cystine (2 g/L).
ANX chromatography. The harvest of 10LBRX-3380-4Xpool-001 from 10 L vessel occurred on day 12 of culture. The column was washed for equilibration with 10 mM Tris-Cl, pH 7.4. The Triton-treated media was diluted with an equal volume (6.60 L) of WFI to prepare the ANX load. The load (13.2 L) was applied to the column. The column was then washed with 10 mM Tris, 100 mM NaCl, pH 7.4 and 3 L of this wash was collected. The APT402 fraction was eluted with 10 mM Tris, 270 mM NaCl, pH 7.4 and collected (2.37 L).
SP Sepharose Chromatography. The column was sanitized with 1M NaOH for over an hour, and then the column was washed with WFI. The column was equilibrated in 10 mM Tris, 50 mM NaCl, 20 mM CaCl2, pH 7.4. The load (ANX elute+9.4 L of 10 mM Tris, pH 7.4+34.5 g of CaCl2 added and stirred 20 minutes, 11.75 L) was applied to the column and the flowthrough, plus wash, collected (˜12 L). The column was washed with 10 mM Tris, 50 mM NaCl, pH 7.4 and the baseline was re-established. The column was eluted with 10 mM Tris, 300 mM NaCl, pH 7.4 and the elution peak collected (1.0 L) as a clear colorless solution.
Heparin Hyper D Chromatography. The column was washed with 10 mM Tris, 1M NaCl, pH 7.4. The column was then equilibrated in 10 mM Tris, pH 7.4. The load (Buffer Exchanged SP Pool, 0.88 L) was applied to the column and the flowthrough, plus wash, collected (1.40 L). The column was stripped of remaining protein with 10 mM Tris, 1 M NaCl, pH 7.4 and this too, was collected (˜100 mL). The chromatogram is shown below. The Heparin flowthrough volume (1.40 L) was buffer exchanged in discontinuous mode using a Masterflex pump and Pellicon Polysulfone 10K membrane into 10 mM Tris, 150 mM NaCl, pH 7.4. The SP pool was concentrated ˜7× to 200 mL, diluted ˜10× with 10 mM Tris, 150 mM NaCl, pH 7.4 to 2.0 L, concentrated again to 200 mL and diluted again ˜10× to 2.0 L with 10 mM Tris, 150 mM NaCl, pH 7.4. Following a third concentration to ˜100 mL, the filter was flushed with 200 mL of 10 mM Tris, 150 mM NaCl, pH 7.4 and this was added to the retentate. The final volume of the concentrate was 300 mL and ˜4.9 L of permeate was collected (˜24.5× the initial concentrate volume). The retentate solution was further concentrated using an Amicon stirred cell apparatus using a 10 kD regenerated cellulose membrane.
The protein was purified to homogeneity. The final recovery yield was ˜54% overall. Bioburden was 0 CFU and endotoxin in the formulated bulk was assayed at 1.0<X<2.0EU/mL or 0.6<X<1.2EU/mg.
APT402 was designed to maintain the enzymatic and biological activity of both APT102 and annexin V. Using malachite green assay, we found the enzymatic kinetic parameters of APT402 for ATP and ADP were comparable to those of APT102. Similarly, APT402 inhibited ADP-induced human platelet aggregation with comparable potency to APT102 (
Thrombin generation in citrated human platelet rich plasma (PRP) was quantified by calibrated automated thrombography (CAT) using the Thrombinoscope system (Synapse), according to methods developed by Hemker et al. Aliquots of PRP were incubated with agents for 15 min at room temperature, and then for 5 min at 37° C. in wells of 96-well plates. Thrombin generation was initiated by addition of 0.5 pM tissue factor and CaCl2 to 16.7 mM and monitored in a microtiter plate fluorometer (Fluoroskan Ascent, Thermo Electron Corp., Vantaa, Finland). Thrombograms (nM thrombin generated vs. time) were generated using the Thrombinoscope software, as were key thrombin generation parameters: lag time to onset of thrombin generation (min), peak thrombin concentration (nM), time to peak thrombin (min), and endogenous thrombin potential (ETP; integrated area under the thrombogram curve).
The effects of APT102, annexin V, APT102+annexin V, and APT402 at equal molar concentrations on thrombin generation from 20 uM ADP-activated human platelets were compared using CAT assays (
APT402 was injected IV as a single bolus (0.40 mg/kg) in two rabbits. Pharmacokinetic modeling showed best fits to biphasic exponential curves for ADPase activity (
The preliminary data indicate APT402 had a short distribution half life. APT402 was then injected IV as a single bolus (0.2 mg/kg) followed by IV infusion at 12 and 24 μg/kg/min for 120 min in rabbits. ELISA data show that APT402 was detectable in the plasma by 30 min after administration. The APT402 concentration, inhibition of ADP-induced platelet aggregation and thrombin generation was maintained up to 120 min during infusion, then significantly decreased 60 min after discontinuation of APT402 infusion (
A near infra-red (NIR) fluorescent dye (LS288, Ex/Em 773/793) in methanol was conjugated to the functional amines of APT402 (˜1:1). The purified bioconjugate showed one fluorescent band (
Rabbits were randomized into the following eleven groups with the treatments initiated 30 min before electrical injury.
Electrical injury generated occlusion in 60% of the rabbits treated with saline within 2 h. Average thrombosis weight was 7.8 mg. Treatment with APT402 at 12 or 24 ug/kg/min, ticagrelor, alone or in combination with angiomax completely prevented occlusion (
An electrical injury model of venous thrombosis was used for acute study (Diaz J A et al. Thromb Haemost. 104: 366-375, 2010.
Mice were randomized into the following four groups (n=10/group).
The EIM consistently generated IVC thrombosis in all mice with the mean thrombus weight of 22.5 mg. Thrombus weight, BT, APTT and TCT were measured 48 h post DVT induction.
Treatment with LMWH reduced thrombus weight by 57% compared to controls and was associated with a significant prolongation of bleeding time by 3-fold, aPTT by 2.5-fold, and TCT by 2-fold (
APT402 dose-dependently reduced thrombus weight by 44% and 65% at the low and high doses, respectively. Importantly, APT402 did not cause detectable prolongation of BT, aPTT or TCT (
These data suggest that APT402 is safe and will be more effective for DVT treatment than enoxaparin due to lack of dose-limiting bleeding.
In a chronic fibrotic study, mice were randomized and blinded into the following groups (n=5-12/group).
Collagen deposition was stained with Masson's trichrome 14 days post DVT induction. The EIM consistently induced IVC fibrosis in all mice and increased mean collagen deposition by approximately 6-fold compared to the healthy mice (
Treatment with APT402 and APT102 significantly reduced collagen deposition by 33% and 11% respectively. There was one death in the placebo group, while no deaths or increased bleeding or gross side effects were observed in the APT402 and APT102 groups.
These data suggest that APT402 is safe and may be an effective treatment for post-thrombotic syndrome.
cgcgtctacgtgtatcaatggccagcagaaaaagagaataataccggagtggtcagtcaa
gccac
aatt
A T I
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/055558 | 3/5/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62986006 | Mar 2020 | US |
