The real-world efficacy and safety of frontline therapy of obinutuzumab plus bendamustine for untreated high-tumor-burden follicular lymphoma.

Background: While R-CHOP has been one of the standard therapies for untreated high-tumor-burden (HTB) follicular lymphoma (FL) for over 2 decades, obinutuzumab plus bendamustine (OB) is also currently regarded as the standard of care since its approval in 2018 in Japan; however, the long-term efficacy and safety of OB in the daily clinical practice has not been thoroughly evaluated.

Methods: We conducted a multicenter retrospective study for the clinical outcome of 53 patients with HTB FL treated by OB as the frontline therapy between 2018 and 2021 in the Kyoto Hematology Clinical Study Group (KOTOSG). All patients had at least 2-year follow-up period.

Results: The median age was 67, and 60.4% were classified as high risk according to the Follicular Lymphoma International Prognostic Index. The overall and complete response rates after induction therapy with OB were 98% and 83%, respectively. With a median follow-up of 38.5 months, the 3-year progression-free survival (PFS) and overall survival (OS) were 77.3% and 91.2%, respectively. Grade 3-4 hematological adverse events (AEs) were common, including neutropenia (58.5%) and lymphopenia (98.1%). Non-hematological AEs included infections, such as lung infections, coronavirus disease 2019, and sepsis, with two cases (3.8%) being fatal. Finally, propensity score-matched analysis showed no significant difference in PFS between 46 FL patients treated by the frontline OB and 46 FL patients treated by R-CHOP between 2001 and 2019 in KOTOSG.

Conclusion: This study highlighted the need for careful treatment selection based on patient background and disease condition in real-world practice with more elderly patients.