Raptiva: Round up the usual suspects

Many compounds developed initially for rheumatoid arthritis are also tested in psoriasis, and vice versa. The reason: T cells appear to play a role in both diseases. But that doesn't mean compounds that work in one disease also work in the other, for reasons that are not yet clear. Such was the case with Raptiva efalizumab from Xoma Inc. and Genentech Inc. Last week, the partners halted a Phase II trial in RA.

While the monoclonal antibody appears to have activity in psoriasis, an indication for which the compound is under FDA and EMEA review, it is unclear why Raptiva failed to show activity in moderate-to-severe RA...