Obinutuzumab (GA101) in patients with relapsed/refractory indolent non-Hodgkin lymphoma: results from the phase II GAUGUIN study.

PURPOSE The phase II part of the phase I/II GAUGUIN study evaluated the efficacy and safety of two different doses of obinutuzumab (GA101), a type II, glycoengineered, humanized anti-CD20 monoclonal antibody, in patients with relapsed/refractory indolent non-Hodgkin lymphoma. PATIENTS AND METHODS Patients were randomly assigned to receive eight cycles of obinutuzumab (GA101) as a flat dose of 400 mg on days 1 and 8 of cycle 1 and also on day 1 of cycles 2 to 8 (400/400 mg) or 1,600 mg on days 1 and 8 of cycle 1 and 800 mg on day 1 of cycles 2 to 8 (1,600/800 mg). RESULTS Forty patients were enrolled, including 34 with follicular lymphoma; 38 of 40 patients had previously received rituximab and 22 of 40 were rituximab refractory. The overall response rate at the end of treatment was 55% (95% CI, 32% to 76%) in the 1,600/800-mg group (9% complete responders) and 17% (95% CI, 4% to 41%) in the 400/400-mg group (no complete responders). Five of 10 rituximab-refractory patients had an end-of-treatment response in the 1,600/800-mg group versus one of 12 in the 400/400-mg group. Median progression-free survival was 11.9 months in the 1,600/800-mg group (range, 1.8 to 33.9+ months) and 6.0 months in the 400/400-mg group (range, 1.0 to 33.9+ months). The most common adverse events were infusion-related reactions (IRRs) seen in 73% of patients, but only two patients had grade 3 to 4 IRRs (both in the 1,600/800-mg group). No IRRs were considered serious, and no patients withdrew for IRRs. CONCLUSION The 1,600/800-mg dose schedule of obinutuzumab (GA101) has encouraging activity with an acceptable safety profile in relapsed/refractory indolent non-Hodgkin lymphoma.