Purpose of review: Targeted inhibitors of B-cell receptor signaling have emerged as the most promising therapeutic options against non-Hodgkin's lymphoma. The inhibitor agents that target Bruton's tyrosine kinase (BTK) have elicited particularly high enthusiasm given the unprecedented positive responses observed in Phase I trials. The sheer amount of clinical data published since last year now requires reinterpretation in light of recently published findings on BTK.
Recent findings: Clinical trial data pertaining to various B-cell dyscrasia forms must be interpreted with great caution. The differing response rates reported with various BTK inhibitors for a range of lymphoma subtypes most likely mirror BTK's disease-specific pivotal role in the regulation of cell survival, migration, and proliferation pathways. It must also be stressed that activating or inhibitory somatic mutations affecting other critical components of targeted signaling cascades dramatically impact BTK inhibitor efficacy, and scientific evidence is mounting that warrants patient screening to identify those who, based on B-cell receptor activation modes, most likely benefit from BTK inhibitors.
Summary: Recent developments in BTK-based therapeutic strategies have undoubtedly changed the way we approach lymphoma therapy. As of yet, there is no cure for indolent lymphoma, and the future of BTK inhibitor therapy will undoubtedly include rational combinations to exploit synthetic lethality in distinct lymphoma subsets.