Immunochemotherapy With Obinutuzumab or Rituximab for Previously Untreated Follicular Lymphoma in the GALLIUM Study: Influence of Chemotherapy on Efficacy and Safety

Purpose The GALLIUM study ( ClinicalTrials.gov identifier: NCT01332968) showed that obinutuzumab (GA101; G) significantly prolonged progression-free survival (PFS) in previously untreated patients with follicular lymphoma relative to rituximab (R) when combined with cyclophosphamide (C), doxorubicin, vincristine (V), and prednisone (P; CHOP); CVP; or bendamustine. This report focuses on the impact of chemotherapy backbone on efficacy and safety. Patients and Methods A total of 1,202 patients with previously untreated follicular lymphoma (grades 1 to 3a), advanced disease (stage III or IV, or stage II with tumor diameter ≥ 7 cm), Eastern Cooperative Oncology Group performance status 0 to 2, and requiring treatment were randomly assigned 1:1 to G 1,000 mg on days 1, 8, and 15 of cycle 1 and day 1 of subsequent cycles or R 375 mg/m² on day 1 of each cycle, for six to eight cycles, depending on chemotherapy (allocated nonrandomly by center). Responding patients received G or R for 2 years or until disease progression. Results Baseline Follicular Lymphoma International Prognostic Index risk, bulky disease, and comorbidities differed by chemotherapy. After 41.1 months median follow-up, PFS (primary end point) was superior for G plus chemotherapy (overall hazard ratio [HR], 0.68; 95% CI, 0.54 to 0.87; P = .0016), with consistent results across chemotherapy backbones (bendamustine: HR, 0.63; 95% CI, 0.46 to 0.88; CHOP: HR, 0.72; 95% CI, 0.48 to 1.10; CVP: HR, 0.79; 95% CI, 0.42 to 1.47). Grade 3 to 5 adverse events, notably cytopenias, were most frequent with CHOP. Grade 3 to 5 infections and second neoplasms were most frequent with bendamustine, which was associated with marked and prolonged reductions in T-cell counts. Fatal events were more frequent in patients treated with bendamustine, possibly reflecting differences in patient risk profiles. Conclusion Improved PFS was observed for G plus chemotherapy for all three chemotherapy backbones. Safety profiles differed, although comparisons are confounded by nonrandom chemotherapy allocation.