Patients with relapsed follicular lymphoma who were treated with obinutuzumab experienced higher response rates than did patients given rituximab with an acceptable safety profile, according to new findings.
However, the difference did not translate into an improvement in progression-free survival, so the clinical value of obinutuzumab in this patient population is still unclear.
The quality of remissions was better with obinutuzumab, with an almost twofold higher complete response/unconfirmed complete response rate (41.9% vs. 22.7%; P = .006),” wrote Dr. Laurie Sehn from the Centre for Lymphoid Cancer, British Columbia Cancer Agency and the University of British Columbia, Vancouver, and her colleagues (J Clin Oncol. 2015 Aug 17. doi:10.1200/JCO.2014.59.2139).
On the basis of an independent review, the best overall response was better in the obinutuzumab arm (P = .04), but the complete response/unconfirmed response rate was not different for the two groups.
The study was published online Aug. 17 in the Journal of Clinical Oncology.
A total of 175 patients with relapsed CD20+ indolent lymphoma were randomized 1:1 to four once-per-week infusions of either obinutuzumab (1,000 mg) or rituximab (375 mg/m2). Those without any evidence of disease progression after completing induction therapy received obinutuzumab or rituximab maintenance therapy every 2 months for up to 2 years.
At the end of induction, the investigator assessed overall response rate was 44.6% in the obinutuzumab arm and 33.3% in the rituximab arm (P = .08); nine patients receiving obinutuzumab (12.2%) and four given rituximab (5.3%) achieved complete response or unconfirmed complete response, but the difference was not significant (P = .07).
Independent review also found the overall response rate to be higher with obinutuzumab vs. rituximab (44.6% vs. 26.7%; P = .01), but with no difference in complete response/unconfirmed complete response rate (5.4 vs. 4.0; P = .34).
Adverse events were similar in each group, and most episodes were grade 1 to 2. Higher rates of infusion-related reactions (74% vs. 51%) and cough (24% vs. 9%) were observed in the obinutuzumab vs. the rituximab arm.
Dr. Sehn receives research funding and honoraria from, and serves in a consulting or advisory role to, Roche/Genentech, the maker of obinutuzumab (Gyzyva) and rituximab (Rituxan). She also receives honoraria from and serves in a consulting or advisory role to Amgen, Janssen, Seattle Genetics, Lundbeck, and Celgene.