Escape from T-cell targeting immunotherapies in acute myeloid leukemia

Single-cell and spatial multimodal technologies have propelled discoveries of the solid tumor microenvironment (TME) molecular features and their correlation with clinical response and resistance to immunotherapy. Computational tools are incessantly being developed to characterize tumor-infiltrating immune cells and to model tumor immune escape. These advances have led to substantial research into T-cell hypofunctional states in the TME and their reinvigoration with T cell-targeting approaches, including checkpoint inhibitors (CPI). Until recently, we lacked a high-dimensional picture of the acute myeloid leukemia (AML) TME, including compositional and functional differences in immune cells between disease onset and post-chemotherapy or post-transplantation relapse, and the dynamic interplay between immune cells and AML blasts at various maturation stages. AML subgroups with heightened interferon (IFN)-g signaling were shown to derive clinical benefit from CD123 x CD3 bispecific DART molecules and CPI, whilst being less likely to respond to standard-of-care cytotoxic chemotherapy. In this Review, we first highlight recent progress into deciphering immune effector states in AML (including T-cell exhaustion and senescence), oncogenic signaling mechanisms that could reduce the susceptibility of AML cells to T cell-mediated killing and the dichotomous roles of type I and II IFN in anti-tumor immunity. In the second part, we discuss how this knowledge could be translated into opportunities to manipulate the AML TME with the aim to overcome resistance to CPI and other T-cell immunotherapies, building on recent success stories in the solid tumor field, and we provide an outlook for the future.