Consolidation Therapy in Primary CNS Lymphoma: Current Evidence and Emerging Approaches

Abstract

Primary Central Nervous System (PCNS) Lymphoma is an aggressive subtype of Large B-Cell Lymphoma (LBCL) present solely in the central nervous system and is identified as its own entity as of the 2017 WHO Classification of Lymphoid Tumors. The disease has a predilection for immunosuppressed individuals, but has also been seen in immunocompetent individuals with no identifiable risk factors. The treatment strategy for PCNSL is continuously evolving and is entirely different from systemic LBCL. This is especially true for consolidation, with conventional methods including high dose chemotherapy followed by autologous stem cell transplant (HDC-ASCT), whole brain radiation therapy (WBRT), or non-myeloablative chemoimmunotherapy (NMC). We aim to summarize the available literature supporting different consolidation strategies for primary CNS lymphoma. We performed a literature search using PubMed and the current clinical guidelines including ESMO and ASCO as a reference. The primary objectives and results of the trials as well as trial design are summarized per method of consolidation. The results generally favor either ASCT or WBRT as opposed to NMC for consolidation given proven OS and PFS benefits compared to chemotherapy alone. There does not appear to be a significant survival difference between ASCT and WBRT. The caveat is that selection criteria for transplant tend to exclude a portion of patients due to age and comorbidities. When compared with stem cell therapy and chemotherapy, WBRT has been shown multiple times to result in increased neurotoxicity. In conclusion, the ideal consolidation strategy remains controversial owing to the unique toxicities, benefits, and selection criteria associated with each strategy. Ongoing studies will provide insight into potential new consolidation methods.