High-dose methotrexate-based chemotherapy for induction remission of newly diagnosed primary CNS lymphoma: A systematic review and meta-analysis

Background:This study aimed to comprehensively assess the optimal regimen for high-dose methotrexate (HD-MTX) in treating primary central nervous system lymphoma (PCNSL). Methods:We have searched 8 databases, including PubMed, EMBASE, Cochrane Library, WOS, Epistemonikos, CNKI, WAN-FANG Database, and CBM, and were selected for the clinical trials about PCNSL. A total of 37 studies were included in our analysis, consisting of 6 randomized controlled trials and 31 single-arm clinical studies. Results:After analyzing the data from 37 clinical studies, we found that the pooled overall response rate (ORR) for low-dose (<3 g/m2), medium-dose (3-5 g/m2), and high-dose (>5 g/m2) methotrexate (MTX) were 0.78, 0.80, and 0.80, respectively. The pooled 2-year overall survival (OS) for low-dose, medium-dose, and high-dose MTX were 52%, 60%, and 71%, respectively. The ORR, complete response (CR), and 2-year OS of patients who received <5 cycles of MTX were 79%, 41%, and 59%, respectively, whereas those for PCNSL patients who received >5 cycles of MTX were 81%, 54%, and 64%, respectively. The pooled ORR for MTX, dual therapy, triplet therapy, tetrad therapy, and multiple therapy were 71%, 70%, 81%, 85%, and 80%, respectively. The pooled 2-year OS for different numbers of medication combinations were 59%, 52%, 66%, 63%, and 60%, respectively. The addition of cytarabine to MTX-based chemotherapy resulted in higher CR, although no statistically significant difference was observed in OS. Adding rituximab to the treatment regimen improved patients' progression-free survival without affecting treatment response or OS. Conclusion:Based on the findings of this study, the treatment strategies of MTX are associated with the prognosis and efficacy response of PCNSL patients. The results suggested that the current recommended HD-MTX dosage of 3.5 g/m2 is sufficient for PCNSL to have a favorable treatment response and prognosis. When the number of MTX treatment cycles increases, the therapeutic effect and prognosis of PCNSL patients are improved. The patients treated with MTX-based triplet combination regimens have a better ORR and CR. Although HD-MTX is generally well tolerated, it is necessary to be cautious about the use of multiple therapy that includes cytarabine to prevent potential acute toxicity.