Drug Shows Major Promise Against Follicular Lymphoma

Radioactive-based therapy put 75% of patients into remission

WEDNESDAY, Feb. 2, 2005 (HealthDay News) -- Just one week of a radioactive-based therapy put three-quarters of 76 people with advanced follicular lymphoma participating in a trial into complete remission.

The results of the new study may push the treatment, currently approved for use after chemotherapy, towards being a first-line treatment, said Dr. Mark Kaminski, lead author of a study appearing in the Feb. 3 issue of the New England Journal of Medicine.

"I think it's an important incremental step," said Dr. Marshall Lichtman, executive vice president of research and medical programs at the Leukemia and Lymphoma Society.

According to an accompanying editorial, follicular lymphoma, the second most common form of non-Hodgkin's lymphoma, is diagnosed in about 15,000 adults in North America each year, with more than 90 percent of those diagnoses being made when the disease has already advanced. Follicular lymphoma is considered incurable in its advanced stages, although it tends to progress slowly.

131 I-tositumomab therapy is currently approved for people who have relapsed after having chemotherapy. Twenty percent to 38 percent of patients who use the therapy after chemo have a complete remission, while 47 percent to 68 percent have some kind of response to the treatment. About 30 percent of the individuals had remissions lasting between one year and 10 years.

Given the success of 131 I-tositumomab as a follow-up treatment, Kaminski and his team decided to test it out as an initial treatment on 76 patients with stage IIII or stage IV follicular lymphoma.

Each participant got two infusions, one week apart.

The overall response rate was 95 percent, while 75 percent went into complete remission. Of those who had a complete remission, 77 percent remained disease-free at five years. The majority (80 percent) had a molecular remission as well. The percentage of people who relapsed decreased with every passing year.

"Instead of a 30 percent complete response rate, we're now up to 75 percent, and the complete response is very much key in getting a long remission," said Kaminski, who is professor of internal medicine in the division of hematology and oncology at the University of Michigan Cancer Center in Ann Arbor.

There were some side effects, but not many.

The duration and ease of the treatment is almost unknown in cancer treatment. Kaminski said he knew only of one other instance where a one-shot treatment induced a remission and that was for hairy cell leukemia, a rare form of cancer.

131 I-tositumomab contains an antibody tagged with a radioisotope which emits radiation. Scientists believe that when the compound is injected into the bloodstream, the antibody zeroes in and binds to a certain protein on the tumor cells so the radiation from the radioisotope can kill the tumor cells. The antibody itself can also kill tumor cells, resulting in a lethal one-two punch to the cancer.

While the results achieved here were similar to those achieved with other therapies, there has been no head-to-head comparison with other treatments.

"It hasn't been compared to the best current therapy, so we still don't know what role this agent would play," Lichtman said. "Would it be used alone, used initially, used with chemo? It had pretty substantial activity, so one could begin thinking about using it earlier."

The patients in this trial were also younger than the average population, which could skew results. "This may be the very best therapy for a subset of patients and may be a very useful addition to other therapies for other subsets. All of these details have to be worked out," Lichtman said.

131 I-tositumomab does have the advantage of being much easier to take than chemotherapy.

Kaminski also expressed caution, however. "The data looks encouraging, but it's going to take more years of follow-up to know if we've cured anybody," he said. "I think this is going to open the door to people feeling more comfortable moving this up and treating patients with this earlier."

More information

The Lymphoma Information Network has more on follicular lymphoma.

SOURCES: Mark Kaminski, M.D., professor, internal medicine, division of hematology and oncology, University of Michigan Cancer Center, Ann Arbor; Marshall Lichtman, M.D., executive vice president, research and medical programs, Leukemia and Lymphoma Society, White Plains, N.Y.; Feb. 3, 2005, New England Journal of Medicine
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