PIK3IP1 Inhibition of PI3K in G1 Arrest Induced by CDK4 Inhibition Reprograms MCL for Ibrutinib Therapy

Inhibition of CDK4/6 has emerged as a promising therapy for diverse human cancers. Mantle cell lymphoma (MCL), in which aberrant cyclin D1 expression and CDK4 activity underlie unrestrained proliferation of tumor cells, remains incurable. Targeting Bruton tyrosine kinase (BTK) with ibrutinibin recurrent MCLhas unprecedented single agent activity, with a completion remission (CR) rate of 21%. However, progression on ibrutinib is virtually universal in MCL and is associated with aggressive proliferation of tumor cells and a dismal clinical outcome.