Genentech Inc. said Thursday that scientists unexpectedly stopped a clinical trial of Rituxan because so-called maintenance doses of the cancer drug prolonged remissions in patients with incurable non-Hodgkin's lymphoma.
The study could open a significant new market for Rituxan, a key profit driver for Genentech and co-marketer Biogen Idec Inc. Rituxan had sales of $1.16 billion last year, but maintenance therapy accounted for just $10 million.
The trial, conducted by the federally funded Eastern Oncology Cooperative Group, tracked 322 patients who received chemotherapy followed by either Rituxan or no treatment. It was stopped this month -- two years earlier than planned -- because patients on Rituxan did significantly better.
Dr. Robert L. Comis of the Eastern Oncology Cooperative Group said data from the trial hadn't been fully analyzed and probably would be presented at a medical conference. He said the study probably would change patient care.
"It is a pretty striking result," he said. "The disease is incurable, so the longer patients are in remission, the better."
But some Wall Street analysts noted the treatment regimen used in the study differs from clinical practice, making the effect of the trial hard to assess.
Patients in the study received a chemotherapy cocktail, which put their disease in remission. After that initial treatment, a group of patients received Rituxan every six months as maintenance therapy, and a second group received no treatment. Typically, non-Hodgkin's lymphoma patients are not treated when their disease is in remission.
Mark Schoenebaum of U.S. Bancorp Piper Jaffray said in a research note that 70% of patients receive a combination of Rituxan and chemotherapy as an initial treatment. A clinical trial in Europe is studying maintenance doses of Rituxan in patients first treated with the Genentech drug and chemotherapy, he said.
The results from the study released Thursday probably would boost Rituxan's use, but "hockey stick"-type growth would not occur without positive results from the European study, which could be completed next year, Schoenebaum said.
Shares in South San Francisco-based Genentech closed at $84.86, up $1.67, on the New York Stock Exchange. Biogen Idec of Cambridge, Mass., closed up $1.83 at $35.25 on Nasdaq.
Thursday's results came on the heels of a human test of Rituxan in patients with a fast-moving form of non-Hodgkin's lymphoma, a curable form of the disease.
Preliminary results from the earlier study, also federally funded, found Rituxan did not improve patient survival.