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CHICAGO -- Treatment with obinutuzumab (Gazyva) reduced the risk of disease progression in patients with rituximab-refractory indolent non-Hodgkin's lymphoma (NHL), researchers reported here.

The median progression free survival (PFS) for patients treated with obinutuzumab plus bendamustine (Treanda) had not yet been reached with a follow-up of 23 months, reported , of the British Columbia Cancer Agency in Vancouver, and colleagues.

In comparison, the PFS for patients on bendamustine alone was 14.9 months, they reported at the American Society of Clinical Oncology annual meeting.

"The combination of obinutuzumab and bendamustine followed by obinutuzumab leads to a clinically relevant and significant improvement compared with bendamustine alone -- a 45% decrease in the risk of disease progression (P=0.0001)," Sehn said, adding that she considered the findings from the randomized, controlled trial to be "remarkable."

"Based on the trial results, the combination of obinutuzumab and bendamustine results in significant benefit," she added. "Certainly, in these patients, there is compelling reason to use obinutuzumab in the setting in which patients are refractory to rituximab [Rituxan] because it would be expected to provide them with clinical benefit."

Obinutuzumab is approved in the U.S. and elsewhere in combination with the chemotherapy drug chlorambucil for treatment of chronic lymphocytic leukemia in adults who have not had previous treatment for that disease.

Obinutuzumab targets the CD20 protein, which is located on the surface of all B cells, including B-cell lymphoma cells. Previous research suggested that when monoclonal antibodies attach to this protein, some lymphoma cells die, and others appear to become more sensitive to chemotherapy.

While obinutuzumab has been tested in smaller clinical trials in various types of lymphoma, this is the first randomized phase III trial to assess the potential benefit of obinutuzumab in patients with NHL, Sehn said.

The study included 396 patients with various types of NHL but the majority (80% were diagnosed with follicular lymphoma. Sehn reported no unexpected side effects or safety concerns from the combination regimen.

Low white blood cell counts and infusion-related reactions were slightly more frequent in the combination arm compared with the bendamustine arm. The rates of low platelet counts, anemia, and pneumonia were higher in the bendamustine alone arm.

The trial was stopped early when the independent data and safety monitoring board determined that the trial had met its primary endpoint, Sehn said at an ASCO press briefing.

Among patients for whom rituximab therapy was no longer effective, the average duration of remission was 29.2 months with the combination versus 14 months with bendamustine.

"Unfortunately, there is yet no cure for indolent lymphoma, so the overall goal of treatment is to increase the amount of time patients remain symptom-free and in remission. The fact that this new approach doubled average remission time marks a major step forward for our patients. Obinutuzumab may offer patients the chance to stay well for a significantly longer period of time, putting off the need for additional chemotherapy," Sehn said in an accompanying press statement.

In the same press statement, ASCO spokesperson , said "it's encouraging to see such impressive results for a novel anti-CD20 monoclonal antibody in a difficult-to-treat patient population ... the fact that this approach stalled cancer progression by more than a year will be good news to patients, who urgently need additional treatment options."

assistant professor of lymphoma/myeloma at the MD Anderson Cancer Center in Houston agreed, telling 番茄社区app that the findings are "a big deal. The population they targeted in this study has been a problem for us. People who progress after taking rituximab do poorly. Having this data shows that adding obinutuzumab to standard chemotherapy bendamustine and the prolongation of obinutuzumab is helpful to these patients."

However, he suggested that more data may be necessary for doctors to change their practice and start using obinutuzumab in these patients.

"I think there are some unanswered questions about the role of the maintenance of obinutuzumab," Westin said. "There are always going to be new questions to be asked when you get a good trial like this. This is thought-provoking and something that could be used in future trials as sort of a benchmark."

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