Intra-Leukemic Interferon Signaling Suppresses Expansion and Mediates Chemoresistance in Human AML.

Intratumoral heterogeneity can affect the competitive fitness and chemoresistance of individual cancer cells. In acute myeloid leukemia (AML), both genetic and functional heterogeneity contribute to chemoresistance, resulting in relapse. Whereas the role of cell-extrinsic factors has been described for AML relapse, whether interactions between cancer cells affect chemoresistance is not fully known. In this study, we demonstrated that a dominant leukemic fraction can suppress the proliferation and expansion of other leukemic cells and that this suppression is reversible. This suppression is mediated in part by both type I and type II intra-leukemic interferon signaling and dependent on BST2. Importantly, blocking antibodies to type II interferon receptor activated the cycling of this suppressed cell fraction and sensitized the cells to subsequent chemotherapy treatment. Our findings suggest that interactions between functionally heterogeneous leukemic fractions can affect competitive fitness and treatment response, highlighting interferon signaling as a potential therapeutic target to counter chemoresistance. SIGNIFICANCE: AML presents a significant challenge in clinical management due to its poor prognosis and high rates of relapse following chemotherapy. Using multiple models of primary human AML, we demonstrate that competitive interactions between leukemia cells affect clonal dynamics and therapy resistance, thereby identifying a potential strategy to improve patient outcomes. See related commentary by Papaioannou and Aifantis, p. 18.