Key Points• IFNa targets Jak2V617F MPN stem cells.Interferon-a (IFNa) is an effective treatment of patients with myeloproliferative neoplasms (MPNs). In addition to inducing hematological responses in most MPN patients, IFNa reduces the JAK2V617F allelic burden and can render the JAK2V617F mutant clone undetectable in some patients. The precise mechanism underlying these responses is incompletely understood and whether the molecular responses that are seen occur due to the effects of IFNa on JAK2V617F mutant stem cells is debated. Using a murine model of Jak2V617F MPN, we investigated the effects of IFNa on Jak2V617F MPN-propagating stem cells in vivo. We report that IFNa treatment induces hematological responses in the model and causes depletion of Jak2V617F MPN-propagating cells over time, impairing disease transplantation. We demonstrate that IFNa treatment induces cell cycle activation of Jak2V617F mutant long-term hematopoietic stem cells and promotes a predetermined erythroid-lineage differentiation program. These findings provide insights into the differential effects of IFNa on Jak2V617F mutant and normal hematopoiesis and suggest that IFNa achieves molecular remissions in MPN patients through its effects on MPN stem cells. Furthermore, these results support combinatorial therapeutic approaches in MPN by concurrently depleting dormant JAK2V617F MPNpropagating stem cells with IFNa and targeting the proliferating downstream progeny with JAK2 inhibitors or cytotoxic chemotherapy. (Blood. 2013;121(18):3692-3702)

Acute myeloid leukaemia (AML) is an aggressive blood cancer caused by the proliferation of immature myeloid cells. The genetic abnormalities underlying AML affect signal transduction pathways, transcription factors and epigenetic modifiers. In solid tumours, it is emerging that the genetic landscape of the tumour has a direct effect on the anti-tumour immune responses and response to immunotherapeutic treatment. However, there remains little information as to whether genetic abnormalities affect anti-leukemic immune responses. This review discusses current knowledge of AML antigens and immune responses to AML with a particular focus on the role of T cells and natural killer cells. Understanding immune responses to AML has implications for the development and use of immunotherapies to treat AML patients with distinct genetic abnormalities.

This is a repository copy of Splicing factor YBX1 mediates persistence of JAK2-mutated neoplasms.