Combinatorial molecule screening identified a novel diterpene and the BET inhibitor CPI-203 as differentiation inducers of primary acute myeloid leukemia cells

Combination therapy has proven effective in treating patients with acute promyelocytic leukemia, highlighting the importance of targeting multiple elements of oncogenic regulation to achieve successful clinical outcomes. However, recent research has revealed that the mutational complexity of acute myeloid leukemia (AML) often prevents the successful translation of molecular targeting strategies into clinical benefit. To address this challenge and complement genetic profiling, we employed an unbiased, combinatorial in vitro drug screening approach to uncover pathways that drive AML and to design personalized combination treatments.

Initially, we screened 513 natural compounds on primary AML cells and discovered a novel diterpene, designated H4, which preferentially promoted differentiation in FLT3 wild-type AML. In contrast, AML cells harboring FLT3-ITD or other mutations exhibited resistance to H4. The AML samples that responded to H4 showed increased expression of myeloid differentiation markers, a marked reduction in the nuclear-to-cytoplasmic ratio, and signs of reactivation of the monocytic transcriptional program, which collectively contributed to reduced leukemia propagation in vivo.

Through combinatorial screening that paired H4 with compounds targeting defined pathways, we found that H4 promotes differentiation by activating the protein kinase C (PKC) signaling pathway. Consistent with this mechanism, treatment with H4 led to PKC phosphorylation and its translocation to the cell membrane. Additionally, our screening identified that co-treatment with a bromodomain and extra-terminal domain (BET) inhibitor further enhanced H4-induced leukemic differentiation in FLT3 wild-type monocytic AML.

These findings underscore the value of integrating unbiased,CPI-203 multiplex drug screening with molecular profiling to develop effective, personalized combination therapies for AML.