The Resistance Mechanisms and Treatment Strategies of BTK Inhibitors in B-cell Lymphoma

Bruton's tyrosine kinase inhibitors (BTKi) have revolutionized the treatment of B-cell lymphoma (BCL). These drugs interfere with the mechanisms underlying malignant B-cell pathophysiology, allowing better drug response as well as low toxicity. However, these multiple mechanisms also lead to drug resistance, which compromised the treatment outcome and needs to be solved urgently. This review focuses on genomic variations (such as BTK and its downstream PCLG2 mutations as well as Del 8p, 2p+, Del 6q/8p, BIRC3, TRAF2, TRAF3, CARD11, MYD88, and CCND1 mutations) and related pathways (such as PI3K/Akt/mTOR, NF-κB, MAPK signaling pathways, overexpression of B-cell lymphoma 6, platelet-derived growth factor, toll-like receptors, and microenvironment, cancer stem cells, and exosomes) involved in cancer pathophysiology to discuss the mechanisms underlying resistance to BTKi. We have also reviewed the newly reported drug resistance mechanisms and the proposed potential treatment strategies (the next-generation BTKi, proteolysis-targeting chimera-BTK, XMU-MP-3, PI3K-Akt-mTOR pathway, MYC or LYN kinase inhibitor, and other small-molecule targeted drugs) to overcome drug resistance. The findings presented in this review lay a strong foundation for further research in this field.