Pemigatinib for the Treatment of Metastatic or Unresectable Colorectal Cancer Harboring FGFR Alterations

Inclusion Criteria: * Registered to Colorectal and Liquid Biopsy Molecularly Assigned Therapy (COLOMATE) Academic and Community Cancer Research United (ACCRU)-GI-1611 and: * COLOMATE Companion Trial Recommendation Form indicates patient qualifies to be screened for a COLOMATE companion trial * COLOMATE Companion Trial Recommendation Form date of completion is =\< 30 days prior to registration * Histologically or cytologically confirmed diagnosis of metastatic or unresectable colorectal cancer (mCRC), based on documentation from local or outside review of pathology according to each site?s established institutional procedure * Documentation of an activating genomic alteration(s) in FGFR1-3 (gain of function mutations, translocations, and amplifications allowed) * Provide informed written consent * Patient must have received and progressed on, or be intolerant to, each of the following treatments for mCRC (or have contraindication to these treatments): * Fluoropyrimidine * Oxaliplatin * Irinotecan * Anti-VEGF (vascular endothelial growth factor) monoclonal antibody, if eligible for this therapy * Anti-EGFR (epidermal growth factor receptor) monoclonal antibody, if eligible for this therapy * Measurable disease * Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0, 1, or 2 * Absolute neutrophil count (ANC) \>= 1500/mm\^3 (obtained =\< 28 days prior to registration) * Platelet count \>= 100,000/mm\^3 (obtained =\< 28 days prior to registration)…