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Diffuse large B cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma among adults, although it also affects the young and the elderly. DLBCL is treated with a chimeric monoclonal antibody against CD20, a B cell surface protein, named rituximab, in combination with a multidrug chemotherapeutic regimen. However, owing to its high cost, rituximab cannot be afforded by patients in developing or underdeveloped countries. In such cases, biosimilars of rituximab have been used instead of rituximab, with equivalent efficacy. In this single center, retrospective, observational study, we have compared patient outcomes such complete response (CR), partial response (PR), and overall response rate (ORR) in a cohort of 152 patients in an Indian hospital, who were treated either with innovator rituximab or Reditux, a biosimilar. We observed that the ORRs of both groups (88% in innnovator group and 82% in biosimilar group) were comparable. There was no statistically significant difference between the two groups in terms of CR (p = 0.353), PR (p = 0.42), ORR (p = 0.23), unfavorable responses, and stable or progressive disease (p = 0.42). The number of patients who died due to complications were few, and there was no significant difference between the two groups. The differences in the 3-year event-free survival and overall survival were not statistically significant. Biosimilar rituximab can suitably and safely replace the innovator rituximab for treatment of diffuse large B cell lymphoma. [ABSTRACT FROM AUTHOR]

Purpose: Rituximab (MabThera™, Roche) is a chimeric IgG1 monoclonal antibody targeting the CD20 surface antigen on normal and neoplastic B cells. It revolutionized the treatment of non-Hodgkin's lymphoma with superior progression-free and overall survival. However, its prohibitively high cost makes it inaccessible to majority of patients in developing countries. Reditux™ (Dr. Reddy's Laboratories, India), a biosimilar, was introduced in India in 2007 at nearly half the price of the innovator. However, there is a dearth of data regarding the pharmacokinetics and efficacy of Reditux™.Methods: Twenty-one patients of diffuse large B-cell lymphoma on R-CHOP regimen were enrolled for the study. Reditux™ was administered as a slow intravenous infusion at a dose of 375 mg/m(2) on day 1 of a 21-day cycle. Pharmacokinetic sampling was performed at pre-dose, post-infusion, 24, 48 h, 7 and 21 days. Rituximab levels were estimated by ELISA. Population pharmacokinetics was performed using NONMEM. In addition, B-cell count was determined at baseline and days 3 and 21 of the first cycle. Survival analysis was performed using Kaplan-Meier plots.Results: The volume of distribution of central compartment and clearance of Reditux™ were estimated at 0.95 L and 5.98 mL/h, respectively. No covariate effects were seen. B-cell count was completely depleted by day 3 and remained so on day 21. Overall survival was 84.6 % at a median follow-up of 36 months.Conclusion: The pharmacokinetic profile and B-cell response to Reditux™ are comparable with those reported for MabThera™. Thus, MabThera™ can be substituted with Reditux™ for the treatment of B-cell lymphomas. [ABSTRACT FROM AUTHOR]