Patent Application
20050002924
The present invention concerns pharmaceutical compositions that contain one of the receptors FcγR IIa, FcγR IIb or FcγR III in a recombinantly produced, soluble form.
Fc receptors (FcRs) play an important role in defence reactions of the immune system, When pathogens have entered the blood circulation they are bound by immunoglobulins, the antibodies. Due to the multivalency of the Fc fragments of the antibodies, the resulting immune complexes bind with high avidity to Fc receptor-presenting phagocytes which destroy and eliminate the pathogens. Accessory cells such as natural killer cells, eosinophils and mast cells also carry Fc receptors on their surface which release stored mediators such as growth factors or toxins after binding of immune complexes that support the immune response.
Hence the Fc receptors of the accessory cells are signal molecules and specifically bind immunoglobulins of various isotypes during the humoral immune response. In addition Fc receptors can activate natural killer cells to destroy antibody-coated target cells (“antibody-dependent cell-mediated cytotoxicity”, ADCC).
However, in addition to the positive effects of FcRs as a defence against pathogens, overshooting reactions may also occur which result in an undesired stimulation of the immune system In healthy persons that manifests itself especially as allergies or autoimmune diseases. Such immune reactions directed against the body's own substances remain a major medical problem and although there are approaches for treating them, they are not equally effective in every patient
Medical problems are also associated with presence of elevated concentrations of natural killer cells (NK cells) which are also formed as a result of overshooting immune reactions. Thus it has been observed that miscarriages frequently occur in pregnant women with an elevated level of NK cells because it hinders the implantation as well as intrauterine growth of the foetus. High doses of immunoglobulins have been previously administered intravenously to treat pregnant women with elevated levels of NK cells. This intravenously administered immunoglobulin G (IVIg) is intended to neutralize NK cells and attenuate the overshooting immune response. IVIg has also been administered for autoimmune diseases (e.g. multiple sclerosis). However, the administration of IVIg in the high doses that are required causes considerable problems. In order to achieve an adequate IVIg concentration in the serum, it is necessary to infuse large amounts of this protein (25-150 g) which is carried out using a relatively large volume (250-1500 ml). This large amount of liquid has to be infused for 2 to 4 hours; a more rapid administration intensifies the side effects that are observed anyway such as headache, fever, general unwellness etc. It has to be administered on 1 to 3 consecutive days and the treatment has to be carried out once every month.
In addition to the considerable amount of time required and the side effects of such an IVIg treatment, another disadvantage is that the treatment is very expensive and costs about US $ 10.000 during a single pregnancy, Moreover, the treatment costs usually have to be borne by the patient herself. An IVIg treatment using a corresponding dosage for e.g. multiple sclerosis or other neurological diseases (Achiron et al., Neurology (1998), 50(2): 398402; Dalakas, Ann. Intem. Med. (1977), 126(9): 721-30; Brannagan et al., Virology (1996), 47(3): 674-7) has the same disadvantages, WO 00/32767 describes soluble Fc receptors which are only composed of the exdracellular part of the receptor and are not glycosylated. Due to the absence of the transmembrane domain and of the signal peptide, these proteins are present in a soluble form and not bound to cells. Furthermore the Fc receptors described in this document can be produced recombinantly and have been suggested for the treatment of autoimmune diseases since they can bind antibodies but do not have an effector effect on other components of the immune system. Hence they are able to neutralize antibodies in the bloodstream which has an attenuating effect especially on autoimmune processes. WO 00/32767 additionally describes the crystal structure of certain Fc receptors and the possibility of finding substances that inhibit the interaction of IgG with Fc receptors with the aid of these crystal structures. The elucidation of the crystal structure allows one to find such inhibitors by screening the available databases with the aid of computer programs.
The object of the present invention was to further develop the findings of WO 00/32767 and to provide treatment methods especially for the indications multiple sclerosis (MS), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) and also for diseases with an elevated level of NK cells which avoid the disadvantages of the previous treatment methods, are easy to use and can be carried out cost-effectively.
This object was achieved within the scope of the present invention by pharmaceutical compositions in the form of aqueous solutions which contain recombinantly produced, soluble FcγR IIa, FcγR IIb FcγR IIb or FcγR III in an amount of 40 to 4000 mg, preferably 100 to 1000 mg and a concentration of up to 50 mg/ml (preferably e.g. 8 ml per injection). Within the scope of the present invention, it was found that in case that said receptors were produced recombinantly in prokaryotes and are therefore unglycosylated, i.e. should be poorly soluble, can nevertheless surprisingly be purified even with known methods in such a manner that a relatively high concentration of sFcR is obtained in a soluble form. Furthermore it was found that these receptors have exceptionally strong effects in combatting overshooting immune reactions even in relatively low doses and in particular at a dose of 0.5 mg/kg to 50 mg/kg body weight.
A preferred pharmaceutical composition, therefore, contains at least one soluble Fc receptor in an amount, which allows application of 0.5 to 50 mg receptor/kg body weight. Due to the availability of the receptors in a highly concentrated soluble form and based on the realization that relatively low amounts of the active sFcR are sufficiently effective, the pharmaceutical composition can be injected and thus laborious infusions lasting for several hours which is quite usual for IVIg treatments can be avoided. Moreover, the pharmaceutical composition according to the invention also generally contains excipients or/and auxiliary substances that are pharmaceutically acceptable and pharmacologically support or facilitate the use of the pharmaceutical composition.
The pharmaceutical composition preferably contains the FcγR IIb receptor which comprises at least the amino acid sequence shown in SEQ ID NO. 1 or the FcγR III receptor with the minimum sequence shown in SEQ ID NO. 2. These two sequences are minimal sequences which can in principle be extended at the termini with suitable sequences of the wild type proteins. It is preferable not to introduce mutations into the constructs when extending the N-termini or/and C-termini of the stated sequences in order to prevent antigenicity. However, it is theoretically possible to also introduce mutations or deletions into the extended sequences provided that they do not result in an undesired antigenicity.
Examples of sequences extended at the termini containing parts of signal or/and linker sequences which, although belonging to the gene, are not absolutely necessary for a therapeutic protein are SEQ ID NO. 3 for FcγR IIb and SEQ ID NO. 4 for FcγR III.
Especially, the receptor FcγR IIb with the amino acid sequence shown in SEQ ID NO. 1 and 3 has proven to be exceptionally effective when used for SLE, MS and RA.
The amounts of receptor required are also unexpectedly low in the case of FcγR III administration since it was found within the scope of the present invention that this recombinantly produced soluble FcR is surprisingly not inactive but even has a 5 to 10-fold higher ability to bind to antibodies than its natural counterpart. Thus again an extremely low dosage of FcR is sufficient and these small amounts can be used for any applications for overshooting immune reactions. Thus FcγR III is especially suitable for use as a substitute for IVIg treatment which again has the already mentioned advantages that a single injection is sufficient to administer adequate amounts of FcR. In contrast to IVIg preparations whose quality varies from batch to batch depending on the donor pool since it is isolated from human serum, the soluble FcRs described here as preferred embodiments can be produced in a constant quality. Another advantage over IvIg is the guaranteed absence of growth factor and human pathogens (e.g. HIV, hepatitis etc.) in case the FcRs are obtained from bacteria. Since it has been found that the FcRs are already effective in e)ctremely low doses and these FcRs can also be purified particularly well and highly concentrated, their administration as an injection solution is particularly preferred. Usually a single administration of the pharmaceutical composition according to the invention is sufficient to considerably improve the symptoms and to delay acute episodes of the diseases. However, a continued application of the injections is of course also advantageous within the scope of the present invention.
Furthermore, the costs of the pharmaceutical compositions according to the invention are very low since their production by recombinant expression in for example prokaryotes is simple and results in highly-purified and highly-concentrated protein preparations. Also expression of the sFcRs in eukaryotic systems can be achieved easily and unexpensively and large amounts can be produced in high purity. Useful systems include eukaryotes with a specialized apparatus for the production of extacellular proteins, e.g. B cells. Hence the pharmaceutical compositions of the present invention can be produced at a fraction of the costs that have to be estimated for IVIg preparations.
Another subject matter of the present invention is the use of the pharmaceutical compositions according to the invention to treat overshooting immune reactions and in particular to treat multiple sclerosis, SLE, RA or to treat patients who have an elevated number of natural killer cells in their bloodstream.
As already described above it is particularly preferred in this case to use the pharmaceutical preparation according to the invention in an injectable form since the pharmaceutical composition according to the invention with its special dosage and concentration allows adequate amounts of soluble Fc receptors to also be administered in this manner. In this connection it is also particularly preferable to use the corresponding FcRs of SEQ ID NO.1 or 2 or proteins extended by wild-type sequences at the N- or/and C-terminus and especially those of SEQ ID NO. 3 or 4. The FcRs can be expressed in prokaryotes and subsequently purified and refolded according to the description of WO 00/32767. The receptors have the advantage that they can be highly concentrated and hence only small volumes are necessary to administer adequately effective amounts. Furthermore, as already described above, it was found within the scope of the present invention that the receptors apparently do not act competitively but that a new mechanism of action occurs with the result that positive effects can already be achieved by administering small amounts of the receptors. The pharmaceutical compositions according to the invention and their use for the treatment of diseases which are based on overshooting immune reactions are therefore particularly advantageous due to their dosage and ease of administration and are particularly well suited for a prolonged treatment also because of their low production costs.
The invention is elucidated by the following figures:
SEQ ID NO.1 shows the preferred minimal amino acid sequence of FcγR IIb which can be optionally extended at the termini.
SEQ ID NO.2 shows the preferred minimal amino acid sequence of FCγR III which can also be extended at the termini.
SEQ ID NO.3 and
SEQ ID NO. 4 show such receptor sequences extended at the termini. SEQ ID NO. 5 shows the preferred minimal amino acid sequence of FcγR IIa which can be optionally extended at the termini.
| Number | Date | Country | Kind |
|---|---|---|---|
| 101 57 290 5 (DE) | Nov 2001 | DE | national |
