PF312 RESPONSES TO R-CHOP CHEMOTHERAPY INCORPORATING BIOSIMILAR RITUXIMAB (TRUXIMA®) FOR THE FIRST LINE TREATMENT OF DIFFUSE LARGE B-CELL LYMPHOMA – INITIAL EXPERIENCE AT UNIVERSITY COLLEGE LONDON HOSPITAL

Abstract

Background: In April 2017 the first biosimilar rituximab (Truxima®; NAPP) was approved in the UK for all indications of the reference biologic (MabThera®; Roche). The adoption of biosimilars is expected to deliver significant cost savings in the treatment of many conditions. The approval of Truxima® was based on comprehensive analytical and pre-clinical testing together with confirmatory clinical trials in advanced follicular lymphoma and rheumatoid arthritis with subsequent extrapolation to all licensed indications of MabThera®. There is an absence of clinical trial data supporting the use of biosimilar rituximab in other haematological malignancies, including diffuse large B-cell lymphoma (DLBCL) where the standard of care is R-CHOP chemo-immunotherapy. In the clinical trial leading to the approval of MabThera® for this indication the complete response rate at the end of treatment was 76% in patients who received R-CHOP compared to 62% in the group who received CHOP alone1. Aims: To assess the response to treatment for all patients treated for de novo stage II-IV DLBCL with R-CHOP chemo-immunotherapy including biosimilar rituximab (Truxima®). Methods: All patients starting treatment with R-CHOP for de novo stage II-IV DLBCL were identified from the electronic chemotherapy prescribing system and the following data collected: baseline demographics, performance status, staging, Revised International Prognostic Index (R-IPI), brand of rituximab received, number of R-CHOP cycles received, number of rituximab doses received, CNS prophylaxis received and response to therapy as assessed by end of treatment PET scan. Results: A total of 70 patients have completed treatment with R-CHOP chemo-immunotherapy incorporating biosimilar rituximab (Truxima®). Patients received a median of 6 cycles of CHOP (range: 1–6) and 6 doses of rituximab (range: 2–8). 58 patients completed treatment exclusively with Truxima®. 12 patients switched from MabThera® to Truxima® during their treatment after a median of 3 doses (range: 1–6). Response rates for the whole cohort of patients were as follows: Complete Response (CR): 51/70 (73%), Partial Response (PR): 11/70 (16%), Progressive Disease (PD): 6/70 (9%). Two patients died before response could be assessed. 4/70 (6%) patients switched from R-CHOP to R-GCVP chemo-immunotherapy after a median of 2 cycles (range: 1–5); all four patients achieved a CR.Summary/Conclusion: In our single-centre experience the use of biosimilar rituximab (Truxima®) does not appear to adversely impact the response rate to R-CHOP chemo-immunotherapy in patients with stage II-IV diffuse large B-cell lymphoma as assessed by post-treatment PET scan. Longer term follow-up in a larger patient group is required to confirm these results.