A Study to Evaluate the Efficacy and Safety of Pemigatinib (INCB054828) in Subjects With Myeloid/Lymphoid Neoplasms With FGFR1 Rearrangement - (FIGHT-203)

Inclusion Criteria: * Documented lymphoid or myeloid neoplasm with 8p11 rearrangement known to lead to FGFR1 activation, based on standard diagnostic cytogenetic evaluation performed locally, before signing informed consent for this study. * Eligible subjects must: * Have relapsed after stem cell transplantation or after other disease modifying therapy, OR * Not be current candidates for stem cell transplantation or other disease modifying therapies. * Note: All relapsed/refractory subjects must have evidence of either cytogenetic or hematological disease and have no evidence of residual toxicity (eg, graft-versus-host disease requiring treatment). * Life expectancy ≥ 12 weeks. * Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2. Exclusion Criteria: * Prior receipt of a selective FGFR inhibitor. * History and/or current evidence of ectopic mineralization/calcification, including but not limited to soft tissue, kidneys, intestine, myocardia, or lung, except calcified lymph nodes and asymptomatic arterial or cartilage/tendon calcifications. * Current evidence of corneal disorder/keratopathy, including but not limited to bullous/band keratopathy, corneal abrasion, inflammation/ulceration, and keratoconjunctivitis, as confirmed by ophthalmologic examination. * Use of any potent cytochrome P450 3A4 inhibitors or inducers within 14 days or 5 half-lives (whichever is shorter) before the first dose of study drug.