JAK1/2 Inhibitor Ruxolitinib for Relapsed/Refractory Immune Bone Marrow Failure

Study Description: This is a prospective, non-randomized, phase I/II study in which participants with relapsed/refractory immune marrow failure (severe aplastic anemia, moderate aplastic anemia, single lineage cytopenias, T-LGL, and hypoplastic MDS) will be treated with the JAK1/2 inhibitor ruxolitinib. Our hypothesis is that JAK1/2 inhibition with ruxolitinib will result in hematologic improvement in participants with immune marrow failure. Objectives: The primary objectives are to assess safety and efficacy of the JAK1/2 inhibitor ruxolitinib in immune marrow failure. The secondary objectives are to assess early and long-term hematologic response, depth of response, development of transfusion independence, rate of relapse, rate of clonal evolution to myeloid malignancy and Paroxysmal Nocturnal Hemoglobinuria (PNH), 3-year overall survival, response after re-initiation of therapy in relapsed participants, maximum tolerated dose. Endpoints: The primary endpoints are: (a) the primary safety endpoint will be number of participants who complete a full course of ruxolitinib without cessation required by hematologic toxicity in the 6 months following treatment initiation; (b) The primary efficacy endpoint is overall response (OR) rate by 6 months. The secondary endpoints are time to OR, OR at 3 months, development of transfusion independence at 3 and 6 months, type of response at 3 and 6 months, rate of relapse up to 3 years, rate of clonal evolution up to 3 years, 3-year overall survival (OS), and number of participants tolerating maximum ruxolitinib dose.