Study to Evaluate the Efficacy and Safety of Pemigatinib in Participants With Relapsed or Refractory Advanced Non-Small Cell Lung Cancer With an FGFR Alteration

Inclusion Criteria: * Histologically or cytologically confirmed advanced or metastatic NSCLC (Stage IIIB/C or IV per the AJCC Cancer Staging Manual, 8th Edition). Both squamous and nonsquamous NSCLC are eligible. * Radiographically measurable disease (per RECIST v1.1). Tumor lesions located in a previously irradiated area, or in an area subjected to other loco-regional therapy, are considered measurable if progression has been clearly demonstrated in the lesion. * Documentation of known/likely actionable known or likely FGFR1-3 alterations. * Must have objective documented progression after at least 1 prior therapy, and must have no therapy available that is likely to provide clinical benefit. Participants who are intolerant of or decline the approved therapy are eligible only if they have no therapy available that is likely to provide clinical benefit. * ECOG performance status of 0 to 2. * Baseline archival tumor specimen (if less than 24 months from date of screening) or willingness to undergo a pretreatment tumor biopsy to obtain the specimen. Must be a tumor block or approximately 15 unstained slides from biopsy or resection of primary tumor or metastasis. * Willingness to avoid pregnancy or fathering a child. Exclusion Criteria * Prior receipt of a selective FGFR inhibitor. * Receipt of anticancer medications or investigational drugs for any indication or reason within 28 days before the first dose of pemigatinib. Participants must have recovered (≤ Grade 1 as per CT…