"Son of Rituxan" in Peril

Trials of the monoclonal antibody ocrelizumab, a humanized version of the uber-mAb rituximab (Rituxan; Genentech/Biogen Idec), in rheumatoid arthritis and lupus have been halted because of drug-related infections and deaths. News of the grave snag in the mAb's phase 3 development (which is evidently not a huge surprise to those in the know) was announced today by the companies and reported in The Street and the WSJ. The study of ocrelizumab in multiple sclerosis, now in the phase 2 stage, continues.

Because profits from ocrelizumab would have been split 70-30, in Genentech's favor, the stalled development actually benefits Biogen Idec to some extent—because the company receives a greater share (40%) of the profits from Rituxan.* (Approval of ocrelizumab for RA, lupus, and any other condition would have eaten into Rituxan sales. A humanized mAb—meaning one that contains fewer mouse parts—is theoretically safer and provides greater long-term efficacy than a chimeric mAb, like Rituxan.)

Share prices of Roche, Genentech's owner,** are largely flat, while Biogen's stock price has climbed steadily since November for reasons that are unclear (to me). Biogen also sells the mAb natalizumab (Tysabri) and an IM version of interferon beta-1a (Avonex), both of which are FDA approved for the treatment of MS.

* An

arbitration ruling over the decision-making rights for the development of ocrelizumab and Rituxan was handed down in June of last year. Net US sales of Rituxan in 2008 totaled nearly $2.6 billion. Rituxan is currently FDA approved to treat non-Hodgkin's lymphoma, chronic lymphocytic leukemia, and RA.

** For those emerging from long-term unconsciousness: Last year, Roche bought Genentech for $46.8 billion USD.

Image of Son of Superman comic book cover from Wikipedia.