1-12-98 WALTHAM, Mass., Jan. 12 /PRNewswire/ – The need for better-tolerated, more- effective immunosuppressive drugs is being fueled by the escalating demand for organ transplants and the increasing prevalence of autoimmune diseases such as rheumatoid arthritis, psoriasis, and systemic lupus erythematosus. Current immunosuppressives can be administered only for limited periods of time, or must be given in combination to avoid side effects; a huge market exists for immunosuppressives that can overcome these limitations.


Sales of immunosuppressives for organ transplantation in the major pharma-ceutical markets are projected to reach $1.7 billion in 2005. A solution to the lack of donor organs for transplantation is being sought through xenotransplantation — the use of an animal organ rather than a human organ. Even when using genetically altered animals (e.g., pigs) that express human inhibitors or other human molecules, immunosuppressive treatment is still required to prevent rejection of the organ tissue. Surgically and physiologically, xenotransplantation will become feasible within the next decade. If xenotransplantation is accepted as a routine procedure, the market could be worth $6 billion by 2010.


Sales of immunosuppressives for psoriasis will total nearly $160 million by 2005, due to the introduction of new biologicals. The market for immunosuppres-sives for rheumatoid arthritis will reach nearly $470 by 2005, reflecting gains made by methotrexate, leflunomide, and new biologicals. Sales of such drugs for lupus will approach $30 million in 2005.


Wyeth-Ayerst’s rapamycin (sirolimus) possibly may be administered at lower doses than those required for cyclosporine and tacrolimus; whether this property will translate into better tolerability remains unclear. Hoechst Marion Roussel’s leflunomide appears to be in a class of its own given its multiple sites of action. The intriguing aspect of leflunomide is its potential, as exhibited in experimental studies, to induce tolerance to autoantigens. Inhibitors of adhesion molecule expression are among the most exciting of the potential new immunosuppressives because of their ability to inhibit both lymphocyte and inflammatory responses.


In the United States, the restrictions on referrals set by HMOs may result in limited access to specialists for patients with chronic illnesses such as psoriasis, lupus, and arthritis. HMO intervention also may delay the timely introduction of new immunosuppressive drugs to treat these conditions.

These developments are evaluated in a new DR Report published by Decision Resources, Immunosuppressive Therapy Markets: Transplant Rejection, Psoriasis, Rheumatoid Arthritis, and Lupus.