Efficacy of central nervous system prophylaxis with stand-alone intrathecal chemotherapy in diffuse large B-cell lymphoma patients treated with anthracycline-based chemotherapy in the rituximab era: a systematic review

Central nervous system (CNS) relapse of diffuse large B-cell lymphoma remains uncommon but catastrophic. The benefit of standalone intrathecal prophylaxis in reducing CNS recurrence is unclear and remains controversial. No systematic review analysing the evidence for stand-alone intrathecal prophylaxis has been performed in the era of anti-CD20 monoclonal antibody therapy. A comprehensive search (01/2002-01/2019) was systematically performed using Ovid MEDLINE(®), Ovid EMBASE(®) and Cochrane. Studies were selected from a total of 804, screened based on predefined inclusion/exclusion criteria, and were critically appraised. Three post hoc analyses (RICOVER-60, RCHOP-14/21, GOYA), one prospective database and 10 retrospective series were included. 7,357 rituximab/obinutuzumab-exposed patients were analysed. The median percentage receiving intrathecal prophylaxis was 11.9%. Cumulative CNS relapse incidence ranged from 1.9% at 6.5 years to 8.4% at 5 years. Median time (of medians) to CNS relapse was 10 months. 73% developed isolated CNS relapses, 24% concurrent CNS/systemic relapse, and 3% post-systemic relapse. Reported CNS relapse sites were: parenchymal (58%), leptomeningeal (27%), and both (12%). Event rates were low resulting in limited power within each study to provide robust univariable/multivariable analysis. Intrathecal prophylaxis was not a univariable or multivariable factor associated with a reduction in CNS relapse in any study. We found no strong evidence for the benefit, or indeed genuine lack of benefit, of stand-alone intrathecal prophylaxis in preventing CNS relapse in diffuse large B-cell lymphoma-treated patients using anthracycline-based immunochemotherapy. Current published study designs limit the strength of such conclusions.