Early efficacy and safety of obinutuzumab with chemotherapy in previously untreated patients with follicular lymphoma: A real-world retrospective report of the Polish Lymphoma Research Group

Background. The first-line obinutuzumab-based immunochemotherapy improves the outcome of patients with follicular lymphoma (FL) compared with rituximab-based regimens. However, infusion-related reactions occur in almost half of patients during the 1st obinutuzumab administration. Objectives. The study aimed to evaluate the early effectiveness and safety of obinutuzumab-based induction regimens in a real-world setting. Materials and methods. Outcomes of patients diagnosed with FL and treated with obinutuzumab between January 2020 and September 2021 were analyzed. Results. The study group included 143 treatment-naive patients with FL. The median age was 52 years (range: 28-89 years); 45.1% of patients had a high-risk disease as assessed using the Follicular Lymphoma International Prognostic Index (FLIPI). Induction chemotherapy included: O-CVP (obinutuzumab, cyclophosphamide, vincristine, prednisolone) in 49.0% of patients, O-CHOP (O-CVP plus doxorubicin) in 28.7% and O-BENDA (obinutuzumab, bendamustine) in 22.4%. Complete response (CR) and partial response (PR) rates were 69.9% and 26.5%, respectively. There was no difference in response rates between different regimens (p = 0.309). Maintenance was started in 115 patients (85.2%). In the 1st cycle, obinutuzumab was administered as a single 1000-milligram infusion in 47.9% of patients, whereas in 52.1%, initial infusions were split over 2 days (100 mg/900 mg). Infusion-related reactions were reported only during the 1st administration of obinutuzumab in 9.1% of patients, with a similar incidence in those receiving the total dose on a single day or split over 2 days (p = 0.458). The most common adverse events were hematological. Five patients died from coronavirus disease 2019 (COVID-19). Conclusions. The early responses to induction regimens and adverse events profile were similar for every type of induction treatment. The infusion-related reactions were rare and limited to the 1st dose of obinutuzumab.