BCL2 and mantle cell lymphoma: ARV‐771 significantly suppressed tumor growth in vivo and improved the survival of mantle cell lymphoma (MCL)-cell-engrafted nude mice, and co-treatment with ARV-771 and ibrutinib or venetoclax (BCL2‐antagonists) or palbociclib (CDK4/6 inhibitor) synergistically induced apoptosis in MCL cells 127.