Combination strategies to promote sensitivity to cytarabine-induced replication stress in acute myeloid leukemia with and without DNMT3A mutations.

Cytarabine and other chain-terminating nucleoside analogs that damage replication forks in rapidly proliferating cells are a cornerstone of leukemia chemotherapy, yet the outcomes remain unsatisfactory because of resistance and toxicity. Better understanding of DNA damage repair and downstream effector mechanisms in different disease subtypes can guide combination strategies that sensitize leukemia cells to cytarabine without increasing side effects. We have previously found that mutations in DNMT3A, one of the most commonly mutated genes in acute myeloid leukemia and associated with poor prognosis, predisposed cells to DNA damage and cell killing by cytarabine, cladribine, and other nucleoside analogs, which coincided with PARP1 dysfunction and DNA repair defect (Venugopal K, Feng Y, Nowialis P, et al. Clin Cancer Res 2022;28:756-769). In this article, we first overview DNA repair mechanisms that remove aberrant chain-terminating nucleotides as determinants of sensitivity or resistance to cytarabine and other nucleoside analogs. Next, we discuss PARP inhibition as a rational strategy to increase cytarabine efficacy in cells without DNMT3A mutations, while considering the implications of PARP inhibitor resistance for promoting clonal hematopoiesis. Finally, we examine the utility of p53 potentiators to boost leukemia cell killing by cytarabine in the context of mutant DNMT3A. Systematic profiling of DNA damage repair proficiency has the potential to uncover subtype-specific therapeutic dependencies in AML.