Bruton's Tyrosine Kinase Inhibitors in Refractory or Relapsing Primary Central Nervous System Lymphoma: A Meta-analysis and Systematic Review

Abstract

Primary central nervous system lymphoma (PCNSL) is an aggressive lymphoma that primarily affects the central nervous system. Current treatments, such as surgery, chemotherapy, and whole-brain radiotherapy, often fail to achieve satisfactory results. The prognosis for patients with refractory or relapsed (R/R) PCNSL is bleak. The optimal treatment for refractory or relapsed PCNSL is poorly defined due to a limited number of studies in this setting. Bruton's tyrosine kinase (BTK) inhibitors, as part of targeted therapy regimens, have undergone testing in several clinical trials against PCNSL and have shown promising results in the treatment of R/R PCNSL. In this meta-analysis, we aim to explore and critically appraise the evidence regarding the efficacy of BTK inhibitors in the treatment of refractory or relapsed PCNSL. A systematic search was conducted on multiple databases including PubMed, Embase, Cochrane library, Wanfang Data Knowledge Service Platform, and CNKI, covering the period up to November 2023. The inclusion criteria for studies were patients with R/R PCNSL who received BTK inhibitors, and reported data on overall response rate (ORR) and complete remission (CR). The pooled rates were calculated using a random-effects or fixed-effects model with a double arcsine transformation, and 95% CIs were determined for all outcomes. In total, 1 studies involving 185 patients were identified and included in the meta-analysis. The pooled complete remission (CR) rate of BTK inhibitors-based treatment for R/R PCNSL was found to be 50%. Subgroup analysis revealed that the CR rates for BTK inhibitor monotherapy, BTK inhibitor combined with chemotherapy, and BTK inhibitor combined with radiotherapy for R/R PCNSL were 7%, 68%, and 80%, respectively. The ORR for BTK inhibitors-based treatment for R/R PCNSL was 70%. Subgroup analysis showed that the ORR rates for BTK inhibitor monotherapy and BTK inhibitor combined with chemotherapy for R/R PCNSL were 55% and 83%, respectively. The most common adverse events (AEs) reported were hematologic AEs, including neutropenia, anemia, and thrombocytopenia. Severe nonhematologic AEs included rash, febrile neutropenia, increased levels of aspartate aminotransferase, and increased blood bilirubin. BTK inhibitors can be regarded as a safe and effective treatment option for R/R PCNSL, thereby providing a potential new avenue for R/R PCNSL treatment. However, it is important to note that further large-sample prospective randomized controlled trials are needed to validate these findings and establish their wider applicability.