LAUSR

Recently, several studies have reported on immunosuppression and infectious complications in patients with myeloproliferative neoplasms (MPN) receiving Janus kinase (JAK) inhibitor therapy (reviewed in [1]). These datasets included analyses of large multicenter trials comparing JAK inhibitor therapy with best available therapy or placebo control. Specific infections such as herpes virus reactivation appear to be more prevalent in patients treated with the JAK inhibitor ruxolitinib (RUX) and opportunistic infections have been described also outside of clinical trials [1]. However, it is not known to which extent the underlying malignancy (MPN) contributes to immunosuppression and susceptibility to infection. Studies from a registry provided early evidence that the risk of MPN patients to die from infections may be increased when compared with normal population controls [2] and this finding was most recently underpinned by a large dataset of 8363 MPN patients [3]. MPN patients were at higher risk for severe bacterial and viral infections judged by hospital admissions and deaths from infection. The question how the type of pharmacologic treatment, the MPN subtype or the disease stage may influence the risk for infectious complications remains still unclear. Immunosuppressive effects of JAK inhibitors are determined by their specificity [4], while other cytoreductive agents such as hydroxycarbamide or interferons may also compromise the function of immune cells. Finally, molecular and clinical heterogeneity of MPN, its impact on cellular signaling, immune function and the inflammatory phenotype may vary depending on the type of driver mutation and disease burden [5, 6]. This international, patient-reported, multicenter pilot study aimed to assess for the overall incidence of infections as well as prophylactic and therapeutic measures in MPN patients in an unbiased manner. The trial included seven academic centers and two private hematology practices in These authors contributed equally: Carl C. Crodel, Kathleen JentschUllrich