Rheumatoid arthritis and the pharmaceutical industry

Other novel approaches

One novel target is to make the small blood vessels in the synovium less sticky, thereby stopping inflammatory cells entering the joint (Step 9). Boehringer Ingelheim is researching into enlimomab, an inhibitor of a molecule that increases stickiness, while Zeneca has identified a compound, ZD7349, that blocks a receptor in blood vessels called VLA4 with similar effects. This has now entered clinical development.

Hoechst Marion Roussel has been investigating leflunomide for several years. It appears to work differently from all other medicines currently being explored. Firstly, it is able to damp down immune responses, including the formation of substances such as rheumatoid factors. Secondly, it slows or halts cell division. The compound has been shown to be effective in clinical trials in people with active disease and is expected to be available during 1998.

Several other approaches are still at the research stage. Chiroscience has made a series of medicines called purine nucleoside phosphorylase (PNP) inhibitors which have shown promise in animal models of arthritis. Sanofi Winthrop is carrying out investigations into sigma receptors as a possible target for new RA medicines. Xenova has a research programme in RA and early pre-clinical immuno-active leads have been identified. Finally, Scotia is developing two naturally occurring products known as fatty acids, both alone and linked to other chemicals. It has been suggested that they may block the production of damaging inflammatory prostaglandins and promote others with a strong protective activity.