Targeted Treatment for RET Fusion-Positive Advanced Non-Small Cell Lung Cancer (A LUNG-MAP Treatment Trial)

Inclusion Criteria: * Patients must have been assigned to S1900B based on biomarker analysis of tissue and/or blood and determined to have RET fusion-positive NSCLC as defined here: * Patients must have RET fusion-positive NSCLC as determined by the Foundation Medicine (FMI) tissue-assay, other tumor-based assays such as next-generation sequencing (NGS), polymerase chain reaction (PCR), or follicular in situ hybridization (FISH), or by cfDNA blood assay. Patients with RET fusions detected by immunohistochemistry (IHC) alone are not eligible. The testing must be done within a laboratory with Clinical Laboratory Improvement Act (CLIA), International Organization for Standardization (ISO/International Electrotechnical Commission (IEC), College of American Pathologists (CAP), or similar certification. Presence of RET fusions detected on tests performed outside of LUNGMAP must have been confirmed by the study biomarker review panel * For patients whose prior therapy was for stage IV or recurrent disease, the patient must have received at least one line of a platinum-based chemotherapy regimen. For patients whose prior systemic therapy was for stage I-III disease only (i.e. patient has not received any treatment for stage IV or recurrent disease), disease progression on platinum-based chemotherapy must have occurred within one year from the last date that the patient received that therapy. Prior anti-PD-1/PD-L1 therapy, alone or in combination (e.g. nivolumab, pembrolizumab, or…