IMMUNOSUPPRESSANT COMPOSITION

Abstract: An immunosuppressant composition comprising: (a) at least one immunosuppressant, such as cyclosporin; and (b) and inhibitor of glycoprotein processing, such as castanospermine; together with a pharmaceutically acceptable carrier or diluent.

Description: "IMMUNOSUPPRESSANT COMPOSITION" This invention relates to an immunosuppressant composition, and in particular it relates to an immunosuppressant composition comprising an inhibitor of glycoprotein processing such as castanospermine or derivatives of castanospermine as one active component thereof. Castanospermine is an alkaloid of the indolizidine class which was first extracted from the Australian native legume Castanospermum australe (Hohenschutze et. al . , 1981). It has the structural formula I depicted below where R 1 , R 2 , R 3 and R* are hydrogen atoms: The related compound, 6-epicastanospermine, has a similar structure except that the stereochemistry at position 6 of the molecule is opposite to that depicted in structural formula I. Castanospermine has recently been shown to have anti-inflammatory and immunomodulatory effects (disclosed in International Patent Application No. PCT/AU89/00341) and is useful in preventing organ transplant (tissue allograft) rejection (Grochowicz et. al . , 1990). It has now been discovered that previously unsuspected benefits can be obtained from the use of castanospermine (or other inhibitors of glycoprotein processing) in conjunction with other clinically useful immunosuppressive drugs or agents, whereby both castanospermine and the additional immunosuppressive drugs or agents may be used at doses lower than those found to be effective when these agents are used individually. This phenomenon allows these immunosuppressive drugs or agents to be used in such a manner that toxic or other undesirable sequelae, such as those described below for drugs such as cyclosporin, azathioprine and glucocorticosteroids, are less likely to be encountered in use. Immunosuppressive drugs such as cyclosporin (also called ciclosporin or cyclosporine) are used at present to improve the initial and probably long term survival of renal allografts, and to mitigate the impact of immunologic risk factors such as H A mismatching and the absence of pre-transplantation blood transfusion. These drugs have also reduced the rate and severity of episodes of rejection on cardiac, hepatic, heart-lung, single-lung and multiple organ and composite organ transplantation in which the risk of lethal immune reactions restricts clinical implementation. They are also used for graft versus host disease associated with bone marrow transplants. The use of cyclosporin and other immunosuppressive drugs, however, is not without problems. The toxic effects include severe neurological, gastrointestinal, hormonal, hepatotoxic, osteoporitic, vascular and, most notably, nephrotoxic symptoms. At present it is necessary for treatment of patients to follow a narrow course between effective immunosuppression and drug toxicity. Such treatment is difficult to achieve when long term immunosuppressive therapy is necessary. According to the present invention there is provided an immunosuppressant composition comprising: (a) at least one immunosuppressant; and (b) an inhibitor of glycoprotein processing; together with a pharmaceutically acceptable carrier or diluent therefor. The present invention also extends to a method of immunosuppressive treatment of an animal or human patient which comprises administration to the patient of an immunosuppressive-effective amount of a composition as broadly described above. The immunosuppressant (a) may be any compound or material known in the art as a clinically useful immunosuppressive drug or agent. Such drugs include, for example, cyclosporin or analogues of cyclosporin, FK506 or analogues of FK506, azathioprine or analogues of azathioprine, or glucocorticosteroids. (FK506 is described, for example, on page APP-1 of The Merck Index, 11th Edition, 1989. ) Other immunosuppressive agents may include various anti-thymocyte (T-cell) globulins, anti T-cell receptor globulins (such as anti-CD 3 or anti-CD 4 globulins), or various anti-cytokine globulins (such as anti-interleukin 1 and anti-interleukin 2, anti-tumour necrosis factor and anti-α-, β- or γ-interferon globulins) or globulin directed against cell surface receptors for these cytokines, which have both demonstrated and potential utility in suppressing organ graft rejections. These agents, like the immunosuppressive drugs mentioned earlier, have demonstrated or potential deleterious dose-limiting side effects. The inhibitors of glycoprotein processing may be selected from the group consisting of castanospermine or an analogue or derivative of castanospermine, or other similar inhibitors of glycoprotein processing such as, nojirimycin or its analogues or derivatives, deoxynojirimycin or its analogues or derivatives, or 6-epicastanospermine or its analogues or derivatives. Suitable derivatives of castanospermine and 6- epicastanospermine for use in the composition of this invention include esters where R 1 , R 2 , R 3 and R 4 in structural formula I are the same or different and are selected from: hydrogen; alkanoyl (straight or branched chain C1-C8); cycloalkanoyl (C3-C7); benzoyl, optionally substituted by methyl, methoxy, ethoxy, propoxy, iso- propoxy, butoxy, sec-butoxy, isobutoxy, phenoxy, benzyloxy,. hydroxy, fluoro, chloro, or bromo; phenylacetyl, optionally substituted by methyl, methoxy, ethoxy, propoxy, iso-propoxy, butoxy, sec-butoxy, isobutoxy, phenoxy, benzyloxy, hydroxy, fluoro, chloro, or bromo; 1- and 2- phenylpropanoyl, optionally substituted by methyl, methoxy, ethoxy, propoxy, isό-propoxy, butoxy, sec-butoxy, isobutoxy,phenoxy, benzyloxy, hydroxy, fluoro, chloro, or bromo; thiophenecarbonyl; pyridinecarbonyl; pyrimidine- carbonyl; and furancarbonyl. Where R 1 , R 2 , R 3 and R 4 in structural formula I are alkanoyl (C1-C8), these substituents are exemplified by formyl; acetyl; propanoyl; isopropanoyl; butanoyl; isobutanoyl; pentanoyl; 2-methylbutanoyl; isopentanoyl; trimethylacetyl; hexanoyl; 2-methylpentanoyl; 3- methylpentanoyl; 2,2-dimethylbutanoyl; heptanoyl; 2- methylhexanoyl; 3-methylhexanoyl; 4-methylhexanoyl; 2,2- dimethylpentanoyl; octanoyl; 2-methylheptanoyl; and 2,2- dimethylhexanoyl. Where R 1 , R 2 , R 3 and R 4 in structural formula I are cycloalkanoyl (C3-C7), these substituents are exemplified by cyclopropanecarbonyl; cyclobutanecarbonyl; cyclopentanecarbonyl; cyclohexanecarbonyl; and cycloheptanecarbonyl. Various quaternary ammonium derivatives of castanospermine (or 6-epicastanospermine) may also be used such as those of structural formula II where R 1 , R 2 , R 3 and R 4 are as described above and R 5 is alkyl (C1-C10) or branched alkyl (C3-C10), and the counter ion, X, is selected from chloride, bromide, iodide, sulfate, phosphate, nitrate, methanesulfonate, acetate, tartrate, citrate, lactate or any other pharmaceutically acceptable anion: Other inhibitors of glycoprotein processing which behave in a similar manner to castanospermine in inhibiting the enzyme glucosidase 1 include deoxynojirimycin and nojirimycin and their derivatives. Deoxynojirimycin is the reduction product of the antibiotic nojirimycin (5-amino-5- deoxy-D-glucose) which is produced by several strains of Streptomyces (e.g. Str. roseoclirogenes , Str. lavendulae and Str. nojirienslε ) . Deoxynojirimycin has the structural formula III where R 1 , R 2 , R 3 , R 4 and R 5 are hydrogen. rπ Suitable derivatives of deoxynojirimycin and nojirimycin include compounds of structural formula III wherein R 1 , R 2 , R 3 and R 4 are the same or different and are selected from the groups described above with reference to structural formula I, and R 5 is hydrogen or methyl. Experiments in animals have shown that doses of castanospermine or cyclosporin which, when administered individually, were too low to prevent host rejection of cardiac allografts proved to be effective at prolonging graft survival when given in combination. Furthermore, this combined therapy has allowed the survival of fully allogeneic cardiac grafts even when the therapy was terminated af er seven days. The present invention is further exemplified in the following Example which demonstrates the immunosuppressive effects of castanospermine in combination with cyclosporin. EXAMPLE 1 This Example demonstrates graft survival of DA rats receiving PVG rat cardiac-allografts where the recipient rats were treated with cyclosporin A (CsA); castanospermine (Cast) or a CsA/Cast composition. The castanospermine was administered to the DA rats on the day of transplantation (day 0) in an Alzet 2 MLI mini-osmotic pump in a 2 ml volume of normal saline. These pumps deliver the drug for 7 days and are then removed, and no further treatment was given. The cyclosporin was administered orally by gavage at one dose/day starting at day 0 and stopping at day 7. The results are set out in Table 1: TABLE 1 Survival of PVG cardiac allografts in DA hosts treated with cyclosporin A, castanospermine or both drugs. These results indicate the potential for the use of lower doses of cyclosporin clinically. This is especially important for kidney transplant recipients, since one of the dose- limiting serious side effects of cyclosporin therapy is nephrotoxicity - the issue of side effects associated with cyclosporin therapy has been well reviewed by Kahan (1989). EXAMPLE 2 This Example demonstrates graft survival in Lewis rats receiving Brown Norwegian rat cardiac-allografts where the recipient rats were treated with cyclosporin A (CsA); castanospermine (Cast) or a CsA/Cast composition. The castanospermine was administered to the Lewis rats on the day of transplantation (day 0) in an Alzet 2 MLI mini- osmotic pump in a voluome of 2 ml. These pumps deliver the drug for 7 days and are then removed, and no further treatment was given. The cyclosporin was administered orally by gavage at one dose/day starting at day 0 and stopping at day 7. The results are set out in Table 2: TABLE 2: Survival of Brown Norwegian cardiac allografts in Lewis hosts treated with cyclosporin A, cas anospermine or both drugs. Table 2 shows the findings from experiments similar to those of Example 1 only in this case the strain combination of rats, Brown Norwegian grafts into Lewis recipients, was much more rigorous. Brown Norwegian into Lewis is one of the most difficult of the rat transplantation combinations; this is reflected in the lower success rate in the CsA 2 + Cast 100 group in this experiment when compared with the PVG into DA experiment shown in Table 1 above. REFERENCES: Grochowicz, P.K., Hibberd, A.D., Clark, D.A. , Bowen, K.M. ,m Cowden, W.B. and Willenborg, D.O. (1990). Castanospermine, an α-glucosidase inhibitor, prolongs renal allograft survival in the rat. Transplant. Proc. 22: 2117- 2118. Hohenschutz, L.D., Bell, E.A., Jewess, P.J., Leworthy, D.P., Pyrce, R.J., Arnold, E. and Clardy, J. (1981). Castanospermine, a1,6,7,8-tetrahydroxy-octahydroindolizine alkaloid, from seeds of Castanospermixm Australe. Phytochemistry. 20: 811-814. Kahan, B.D. (1989). Cyclosporine. N.Engl. J. Med. 321: 1725-1738.

Claims: CLAIMS : 1. An immunosuppressant composition comprising (a) at least one immunosuppressant; and (b) an inhibitor of glycoprotein processing; together with a pharmaceutically acceptable carrier or diluent therefor. 2. A composition of claim 1, wherein said immunosuppressant is selected from the group consisting of cyclosporin and analogues of cyclosporin, FK506 and analogues of FK506, azathioprine and analogues of azathioprine, and glucocorticosteroids. 3. A composition of claim 1, wherein said immunosuppressant is selected from the group consisting of anti-thymocyte (T-cell) globulins, anti-T-cell receptor globulins, anti-cytokine globulins, and anti-cytokine receptor globulins. 4. A composition of claim 1, wherein said immunosuppressant is cyclosporin. 5. A composition of claim 1, wherein said inhibitor of glycoprotein processing is selected from the group consisting of castanospermine or an analogue or derivative of castanospermine, nojirimycin or its analogues or derivatives, deoxynojirimycin or its analogues or derivatives, or 6-epicastanospermine or its analogues or derivatives. 6. A composition of claim 1, wherein said inhibitor of glycoprotein processing is selected from (i) castanospermine or derivatives thereof having the structural formula I: wherein R 1 , R 2 , R 3 and R 4 are the same or different and each represents hydrogen; alkanoyl (straight or branched chain C1-C8); cycloalkanoyl (C3-C7); benzoyl, optionally substituted by methyl, methoxy, ethoxy, propoxy, iso- propoxy, butoxy, sec-butoxy, isobutoxy, phenoxy, benzyloxy, hydroxy, fluoro, chloro, or bromo; phenylacetyl, optionally substituted by methyl, methoxy, ethoxy, propoxy, iso-propoxy, butoxy, sec-butoxy, isobutoxy, phenoxy, benzyloxy, hydroxy, fluoro, chloro, or bromo; 1- and 2- phenylpropanoyl, optionally substituted by methyl, methoxy, ethoxy, propoxy, iso-propoxy, butoxy, sec-butoxy, isobutoxy,phenoxy, benzyloxy, hydroxy, fluoro, chloro, or bromo; thiophenecarbonyl; pyridinecarbonyl; pyrimidine- carbonyl; and furancarbonyl; or the structural formula II: OR .'3 where R 1 , R 2 , R 3 and R 4 are as defined above, and R 5 is alkyl (C1-C10) or branched alkyl (C3-C10), and X is a pharmaceutically acceptable anion; and (ii) 6-epimers thereof. 7. A composition of claim 1, wherein said inhibitor of glycoprotein processing is selected from deoxynojirimycin or derivatives thereof having the structural formula III: wherein R 1 , R 2 , R 3 and R 4 are as defined in claim 6, and R 5 is hydrogen or methyl. 8. A composition of claim 1, wherein said inhibitor of glycoprotein processing is castanospermine. 9. An immunosuppressant composition of claim 1, comprising cyclosporin and castanospermine, together with a pharmaceutically acceptable carrier or diluent. 10. A method of immunosuppressive treatment of an animal or human patient which comprises administration of an immunosuppressive effective amount of a composition of any of claims 1 to 9. 11. Use of a composition of any of claims 1 to 9 for immunosuppressive treatment of an animal or human patient. 12. Use of a composition of any of claims 1 to 9 for manufacture of a medicament for immunosuppressive treatment of an animal or human patient.

Inventors: BOWEN KERRY M, COWDEN WILLIAM B, HIBBERD ADRIAN D, PARISH CHRISTOPHER R, WILLENBORG DAVID O, BOWEN, KERRY, M., COWDEN, WILLIAM, B., HIBBERD, ADRIAN, D., PARISH, CHRISTOPHER, R., WILLENBORG, DAVID, O.
Applicants: PEPTIDE TECHNOLOGY LTD, UNIV AUSTRALIAN, PEPTIDE TECHNOLOGY LIMITED, THE AUSTRALIAN NATIONAL UNIVERSITY
Application year: 1991
Main classification: A61K45
IPC codes: A61K31, A61K38, A61K39