Biosimilar Rituximab (Redditux) Added to CHOP Chemotherapy for De Novo Diffuse Large B-Cell Lymphoma Patients: Real-Life Single-Center Experience.

Objective: Redditux (RED), as a biosimilar rituximab, was approved in Turkey for all indications of the original Mabthera (MAB) in March 2018. The aim of our study was to evaluate the efficacy and safety of RED in de novo diffuse large B-cell lymphoma.

Materials And Methods: Fifty-one patients received RED combined with the CHOP regimen. The median follow-up was 31 months. The historical control group included 219 patients treated with the MAB-CHOP regimen and the median follow-up time was 38 months. We compared the response rates and survival outcomes of these RED-CHOP and MAB-CHOP cohorts.

Results: In the RED cohort, the overall response rate (ORR) at the end of the treatment protocol was 86%, with 37 (72.5%) cases of complete response (CR) and 7 (13.5%) cases of partial response (PR). In the historical MAB cohort, the ORR was 84%, with CR and PR rates of 82% and 2%, respectively. The 24-month progression-free survival (PFS) rates were 73.76% (95% confidence interval [CI]: 0.59-0.84) and 85.2% (95% CI: 0.79-0.90) for the RED and MAB cohorts, respectively (p=0.0106). The 24-month overall survival rates were 78.4% (95% CI: 0.64-0.87) and 81.4% (95% CI: 0.75-0.86) for the RED and MAB cohorts, respectively (p=0.7461). For patients with high revised International Prognostic Index scores, 24-month PFS was 45.5% (95% CI: 0.17-0.71) and 63% (95% CI: 0.37-0.80) for the RED and MAB cohorts, respectively (p=0.0711). In the RED cohort, central nervous system (CNS) relapse was significantly increased compared to the MAB cohort (10% vs. 1.83%, p=0.004). Among the RED cohort, bone involvement at the time of diagnosis was a risk factor for CNS relapse (p=0.028). Thirteen patients died in follow-up. There were no serious adverse events causing the cessation of the drugs.

Conclusion: RED has an ORR similar to that of MAB. However, PFS rates were worse in the RED cohort. Additionally, CNS relapse ratio was a major concern for our RED cohort. Large prospective controlled studies and real-life data with longer follow-up are needed to document the non-inferiority of RED compared to MAB.