New scaffolds for type II JAK2 inhibitors overcome the acquired G993A resistance mutation.

Recurrent JAK2 alterations are observed in myeloproliferative neoplasms, B-cell acute lymphoblastic leukemia, and other hematologic malignancies. Currently available type I JAK2 inhibitors have limited activity in these diseases. Preclinical data support the improved efficacy of type II JAK2 inhibitors, which lock the kinase in the inactive conformation. By screening small molecule libraries, we identified a lead compound with JAK2 selectivity. We highlight analogs with on-target biochemical and cellular activity and demonstrate in vivo activity using a mouse model of polycythemia vera. We present a co-crystal structure that confirms the type II binding mode of our compounds with the "DFG-out" conformation of the JAK2 activation loop. Finally, we identify a JAK2 G993A mutation that confers resistance to the type II JAK2 inhibitor CHZ868 but not to our analogs. These data provide a template for identifying novel type II kinase inhibitors and inform further development of agents targeting JAK2 that overcome resistance.

Adherence to long-term follow-up preventive practices in allogeneic hematopoietic cell transplantation survivors from North India.

Introduction: There are existing international guidelines for long-term follow-up (LTFU) care of allogeneic hematopoietic cell transplantation (allo-HCT) survivors. However, implementing these guidelines represents a unique challenge in resource-challenged settings. Methods: This study aimed to evaluate adherence to recommended surveillance in allo-HCT survivors at an academic center in North India and study the incidence of late effects. This single-center, retrospective study analyzed records of allo-HCT recipients from 2016 to 2020. Survivors were screened in our LTFU clinic at day +100 and +365 using cardiometabolic parameters (screening for hypertension, dyslipidemia, hyperglycemia, 24-hour urine protein, thyroid function), pulmonary function test (PFT), bone mineral density (BMD), and initiation of revaccination. Results: A total of 40/80 (50%) allo-HCT survivors were alive at a median of 888 days (IQR 515-1,306). The adherence to home-based screening parameters such as blood pressure and blood glucose was highest (>75%), followed by lab-based parameters (45-70%), and lowest for specialized tests such as PFT (<50%) at both day +100 and +365 time points. Adherence to the initiation of revaccination was only 67%. At least one cardiometabolic parameter was out of range in 55% and 63% of survivors at day +100 and +365, respectively. Conclusion: The adherence to recommended surveillance measures for allo-HCT survivors in an academic LTFU clinic at one year was only 75% overall. Cardiometabolic abnormalities were noted in more than half of the survivors. This study emphasizes the need for a structured LTFU clinic in all centers performing HCT.