LOS ANGELES (Reuters) - Continued use of Rituxan cut by about 50 percent the risk that follicular lymphoma patients would have their cancer return, according to a late-stage study of the drug, which is sold by Roche Holding AG and Biogen Idec Inc.
Last year Rituxan, known outside the United States as MabThera, met the target of extending the time patients lived with their cancer in remission during an interim look at the results. An outside monitoring committee then stopped the study.
Roche and Biogen have already filed in the United States and Europe to extend the current label for the drug to include such “maintenance” treatment for patients with advanced follicular lymphoma.
The Phase III trial involved more than 1,000 patients whose disease was already reduced or eliminated after initial treatment with a combination of chemotherapy and Rituxan, also known as rituximab.
After two additional years of treatment with Rituxan alone, 82 percent of patients who received Rituxan were in remission, compared with 66 percent of the group not treated with Rituxan.
Citigroup analysts estimated that some 70 percent of U.S. patients already use Rituxan as a maintenance therapy, compared with 10 percent or 15 percent in Europe and emerging markets.
“The drug is penetrated in this indication in the U.S. but not elsewhere leaving $500 million sales potential,” Deutsche Bank analyst Tim Race said in a research note on Thursday.
Follicular lymphoma is a slow-developing but incurable form of non-Hodgkin’s lymphoma. It is one of the most common types of lymphoma, which is a cancer of the lymphatic system.
Most patients with this type of lymphoma are at risk for a relapse within three to six years of their initial therapy, according to Dr. Gilles Salles, professor of medicine at the University of Lyon and the study’s lead author.
“It is a disease that we think we can’t cure but we again are turning it into a chronic illness,” said Dr. Douglas Blayney, president of the American Society of Clinical Oncology.
Rituxan, first approved in 1997, is currently marketed for treating non-Hodgkin’s lymphoma, rheumatoid arthritis and chronic lymphocytic leukemia. Sales last year totaled 6.1 billion Swiss francs, or about $5.6 billion.
The drug, given by infusion, is an antibody that binds to a specific protein found on the surface of malignant and normal B-cell lymphocytes, enlisting the body’s own immune system to kill marked cells.
Follow-up to gauge overall survival of the patients is continuing, according to a spokeswoman for Roche’s Genentech unit.
The key question is whether these data will translate into a survival benefit, said Dr. George Sledge, ASCO’s president-elect. “This is an important step in that direction,” he said.
The study found benefits of rituximab maintenance regardless of patients’ stage of remission, age, or prior treatment regimen, the researchers said.
The most common side effects were infections, which occurred in 37 percent of the Rituxan group and 22 percent of the observation group.
The full two years of Rituxan maintenance regimen studied in the trial would have a wholesale cost of about $48,000.
Additional reporting by Ben Hirschler in London