Objectives:   To evaluate the safety, efficacy, and feasibility of using rituximab in combination with fotemustine, pemetrexed, and dexamethasone (R-FPD) in primary central nervous system lymphoma (PCNSL). To undertake an initial exploration of the significance of biomarkers in PCNSL.

  Methods   This was a prospective, single-center, single-arm, phase Ⅱ clinical trial. Patients newly diagnosed with PCNSL from the First Affiliated Hospital of Zhengzhou University from July 2018 to July 2019 were enrolled. All patients underwent first-line chemotherapy with R-FPD. The primary study endpoints were:objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). The secondary study endpoint was:adverse reactions (ADR).

  Results   Twelve patients were included in the study. After four cycles of treatment, six patients had complete remission, two had partial remission, one was stable, and three progressed. The ORR was 66.7%, DCR was 75%, and median PFS was 7 months (95% confidence interval:4.4-9.6 months). The median OS was 10.5 months (95% confidence interval:6.1-14.9 months). The main adverse reaction due to RFPD chemotherapy was hematologic toxicity, and grade Ⅲ-Ⅳ neutropenia and thrombocytopenia were observed (16.7% and 25%, respectively). High expression of c-myc protein (>40%) did not appear to be significantly associated with prognosis.

  Conclusions   R-FPD is an effective and safe protocol for the treatment of newly diagnosed PCNSL patients. There was no significant relationship between high c-myc expression and prognosis.