Here, through the discovery of a highly selective PI3Kδ/Vps34 inhibitor PI3KD/V-IN-01, which can efficiently block the PI3Kδ mediated signaling pathway and autophagy, we found that dual inhibition of PI3Kδ and Vps34 greatly enhances the anti-proliferative effects of single PI3Kδ and Vps34 inhibitors in B-cell cancers such as AML, CLL, and B-NHL. Here, PIK3C3 is linked to B-cell chronic lymphocytic leukemia.