On point in primary CNS lymphoma

Primary CNS lymphoma (PCNSL) is an aggressive brain tumor that represents a significant challenge both to elucidate its biological pathogenesis as well as to develop definitive precision medicines with minimal collateral toxicity. We highlight the key issues in diagnosis and treatment and focus on emerging technologies, current options among consolidation strategies, and biological agents. We anticipate that further development of molecular diagnostics and molecular imaging approaches that elucidate minimal residual disease in brain parenchyma, leptomeninges, intraocular compartments and even bone marrow will greatly impact the delivery and timing of cytotoxic and biological therapies. Implementation of these approaches is likely essential to clarify ongoing discrepancies in the interpretation of clinical trial results that currently are based on relatively unrefined definitions of response. While the results of early phase investigations involving ibrutinib and the IMiD agents, lenalidomide, pomalidomide, as well as avadomide, strongly support the hypothesis that the B-cell receptor (BCR) pathway, involving MYD88 and CD79B and NF-kB activation, is critical to the pathogenesis of PCNSL, much work is needed to elucidate mechanisms of resistance. Similarly, development of strategies to overcome immunosuppressive mechanisms that are upregulated in the tumor microenvironment is a high priority. Finally, ongoing evidence supports the hypothesis that the blood-brain barrier represents a significant impediment to efficient brain tumor penetration of novel therapeutic agents and innovative strategies of drug delivery remain essential to further improve outcomes.