Safety of chidamide plus rituximab in elderly patients with relapsed or refractory B-cell lymphoma in China: a multicenter, single-arm, phase II study

Background: Patients over 65 years old with diffuse large B-cell lymphoma (DLBCL) or follicular lymphoma (FL) relapse or being refractory to rituximab-associated chemotherapy have limited treatment options. Chidamide has the ability to enhance the sensitivity of rituximab-resistant tumors in vivo has been confirmed. We aimed to assess the activity and safety profile of chidamide plus rituximab in elderly Chinese patients with recurrent or refractory B-cell lymphoma. Methods: In this prospective, single-arm phase II trial, we enrolled patients from three hospitals in China with histopathological diagnoses of DLBCL and FL who had relapsed or were refractory to previous lines of rituximab-associated chemotherapy. Patients were given chidamide (10 mg on days 1-6 and 8-14) and rituximab (375 mg/m(2) on day 7). The treatments were repeated every 21 days. The primary endpoint was the objective response rate (ORR). The secondary endpoints included the disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety. Results: Thirteen patients were enrolled and commenced treatment between November 12, 2018, and December 24, 2020. As of March 20, 2021, two patients (15.4%) were still receiving treatment. The median follow-up was 13.4 months. The ORR was 40% for the DLBCL cohort (n=10), and 100% for the FL cohort (n=3). DLBCL patients had a median PFS (mPFS) of 2.6 months (0.9-31.2 months) and a median OS (mOS) of 16.7 months (2.3-13.6 months). Neither mPFS nor mOS was reached in the FL cohort. The most frequent treatment-related adverse events (TRAFs) were leukopenia (38.5%), neutropenia (30.8%), lymphopenia (30.8%), thrombocytopenia (30.8%), fatigue (38.5%), and hyperuricemia (30.8%). Conclusions: Chidamide plus rituximab is clinically effective with an acceptable toxicity profile in elderly patients over 65 years old with relapsed or refractory DLBCL and FL. Further investigation is ongoing.