Lymphoma Drug Bexxar Effective Over Long Term, Study Finds

The patients had follicular lymphoma, a type of cancer that is not considered to be curable using traditional treatments. Even if patients initially respond to treatment, the disease almost always comes back and becomes more difficult to treat.

The study followed 76 patients with follicular non-Hodgkin's lymphoma, a cancer of the lymph system, who received the radioimmunotherapy drug Bexxar as their first treatment for the disease. Ninety-five percent of the patients saw their tumors shrink from the treatment and three-quarters of patients went into complete remission. Patients were followed for a median of eight years, and nearly two-thirds have remained in complete remission eight years after treatment.

"For years we have known radioimmunotherapy such as Bexxar is one of the most effective treatments for patients with relapsed follicular lymphoma. These data show Bexxar is particularly effective when used as a frontline treatment," says Mark Kaminski, M.D., professor of internal medicine at the U-M Medical School. Kaminski will present these results June 4 at the American Society of Clinical Oncology annual meeting in Chicago.

"These results compare quite favorably with those achieved with state-of-the-art chemotherapy regimens that take months to deliver. But Bexxar is given as a single treatment, completed within one week, which makes it an extremely convenient regimen for patients," Kaminski says.

Non-Hodgkin's lymphoma, the nation's sixth leading cause of cancer death, is a cancer of the lymph system, which is part of the immune system. Follicular lymphoma is the second most common type of non-Hodgkin's lymphoma. Lymphoma spreads easily through the lymph system and the bloodstream and consequently tends to be widespread when it is diagnosed. Traditional treatment often involves intensive chemotherapy, or a combination of chemotherapy and the monoclonal antibody rituximab. These treatments are usually given every three weeks over a span of up to six months and can cause many unpleasant side effects, including nausea, hair loss and infections.

Bexxar, whose chemical name is tositumomab and iodine I 131 tositumomab, combines an antibody that seeks out cancer cells, and a radioactive form of the element iodine. When injected, it travels like a guided missile through the bloodstream to bind to a protein found on the surface of the cancerous cells. The radiation zaps these malignant cells with minimal exposure to normal tissues.

With the Bexxar therapeutic regimen, a patient receives an injected test dose of radioactive Bexxar, followed one to two weeks later with a custom-tailored therapeutic dose. After that, the therapy is considered complete. The most common side effect is a temporary lowering of blood counts several weeks after the treatment. There is no hair loss and nausea is rare.

Kaminski and his colleague Richard Wahl (formerly at U-M and now at Johns Hopkins University) developed the Bexxar regimen, which received approval from the U.S. Food and Drug Administration in June 2003 to treat follicular non-Hodgkin's lymphoma after other treatments have failed. The current results involve Bexxar as a first-line treatment for this disease.

In addition to Kaminski and Wahl, U-M study authors were Judith Estes, R.N., a nurse practitioner; Missy Tuck, clinical research coordinator; and Charles Ross, M.D., associate professor of pathology.

Funding for the study was from the National Institutes of Health and GlaxoSmithKline. The University of Michigan holds patents for the Bexxar therapeutic regimen, which is marketed by GlaxoSmithKline under a licensing agreement. U-M receives royalties on sales of Bexxar, a portion of which goes to Kaminski and his co-inventors.

Reference: American Society of Clinical Oncology 43rd annual meeting, June 1-5, 2007, Chicago, Ill. Abstract No. 8033.