Biology of CNS lymphoma and the potential of novel agents

Primary and secondary CNS lymphomas are aggressive brain tumors that pose an immense challenge to define in terms of molecular pathogenesis, as well as to effectively treat. During the past 10 years improvements in survival have been achieved with the implementation of anti-CD20 immunotherapy and optimization of dose-intensive consolidation strategies. The applications of whole-exome sequencing, comparative genomic hybridization, transcriptional profiling, and examination of the tumor microenvironment, particularly in the context of clinical investigation, provide insights that create a roadmap for the development and implementation of novel targeted agents for this disease. A body of genetic evidence strongly suggested that primary CNS lymphomas (PCNSLs) are likely largely dependent on NF-κB prosurvival signals, with enrichment of mutations involving the B-cell receptor pathway, in particular myeloid differentiation primary response 88 and cluster of differentiation 79B. The first set of early-phase investigations that target NF-κB in PCNSL have now been completed and support the NF-κB hypothesis but at the same time reveal that much work needs to be done to translate these results into meaningful advances in survival for a large fraction of patients. Insights into secondary prosurvival pathways that mediate drug resistance is a priority for investigation. Similarly, further evaluation of the immune-suppressive mechanisms in the CNS lymphoma tumor microenvironment is requisite for progress. Combinatorial interventions that promote the antitumor immune response have significant potential. With increasing availability of targeted agents, there is also a need to develop more sensitive imaging tools, not only to detect this highly invasive brain neoplasm but also potentially to define an evolving molecular phenotype to facilitate precision medicine.