High-dose methotrexate-based regimens with or without vincristine for the treatment of primary central nervous system lymphoma

Background. Primary central nervous system lymphoma (PCNSL) is a rare malignancy with few treatment options. One regimen used for induction is rituximab, high-dose methotrexate (HD-MTX), procarbazine, and vincristine (R-MPV). A common institutional practice is removing vincristine (VCR) from this regimen due to its poor CNS penetration and associated toxicities. The aim of this study was to evaluate how the omission of VCR from HD-MTX-based induction impacted clinical outcomes. Methods. In a retrospective review, patients with PCNSL who received HD-MTX-based induction therapy between January 1, 2010 and May 31, 2018 were evaluated. Patients were stratified according to treatment into 2 groups, VCR-containing therapy versus no VCR. The primary endpoint was complete response (CR) rate following the completion of induction chemotherapy. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and adverse event rate. Results. Twenty-nine patients were included: 16 patients in the VCR group and 13 in the non-VCR group. A CR was achieved in 7 (44%) and 5 (38%) (odds ratio [OR] = 1.24; 95% confidence interval [CI]: 0.28-5.53) patients, respectively. Median OS was 85.3 (95% CI: 20.2-85.3) versus 67.1 months (95% CI: 10.5-NR) and median PFS was 60.7 (95% CI: 9.4-NR) versus 23.7 months (95% CI: 4.7-NR) in the VCR group versus non-VCR group, respectively. The incidence of any grade peripheral neuropathy was higher in the VCR group. Conclusions. CR rate, OS, and PFS were similar between groups regardless of VCR inclusion. Adverse events were higher in the VCR group. Larger studies are required to further evaluate the efficacy of VCR in PCNSL induction regimens.