Clinical Research Directory

Inclusion Criteria: * Participants with one of the following RET-altered cancers: * Adults with advanced RET fusion-positive Non-small cell lung cancer (NSCLC) who require systemic therapy * Adults and pediatric participants (greater than or equal to 12 years) with advanced RET-mutant Medullary Thyroid Cancer (MTC) who require systemic therapy * Adults and pediatric participants (greater than or equal to 12 years) with advanced RET fusion-positive thyroid cancer who require systemic therapy, or * Adults and pediatric participants (greater than or equal to 12 years) with advanced or metastatic RET fusion-positive solid tumors with disease progression on or after prior systemic therapies or who have no satisfactory therapeutic options * RET gene fusion or mutation in tumor identified using polymerase chain reaction (PCR) or next-generation sequencing (NGS) * Radiographic progressive disease per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 at screening * Eastern Cooperative Oncology Group performance status score of 0 to 2 * Have not received more than 1 cycle of first-line non-targeted therapy * Men and women of childbearing potential must agree to use a highly effective contraceptive method during treatment with study drug and for 2 weeks following the last dose of study drug * Must have adequate organ function, as defined in the protocol. Exclusion Criteria: * Additional validated oncogenic drivers in NSCLC if known OR have additional validated oncogenic driver in MTC if known that could cause resistance to selpercatinib treatment. * Symptomatic central nervous system metastases, carcinomatous meningitis, or untreated spinal cord compression. * Clinically significant active cardiovascular disease or history of heart attack within 6 months, history of Torsades de Pointes, or prolongation of the QTcF \>470 milliseconds on more than 1 electrocardiogram (ECG) during screening. * History of human immunodeficiency virus (HIV) * Active hepatitis B (HBV) or C (HVC) * Active uncontrolled systemic bacterial, viral or fungal infection or serious ongoing incurrent illness (such as high blood pressure or diabetes, interstitial lung disease) * Uncontrolled, disease related, pericardial effusion, or pleural effusion * Uncontrolled symptomatic overactive or underactive thyroid * Uncontrolled symptomatic high or low levels of calcium in the blood * Active hemorrhage or at significant risk for hemorrhage * Active malabsorption syndrome or other conditions likely to affect gastrointestinal (GI) absorption of study drug * Other malignancy unless non-melanoma skin cancer, carcinoma in situ of the cervix or other in situ cancers, or malignancy diagnosed greater than or equal to 2 years previously and not currently active. Participants receiving adjuvant hormone therapy for breast cancer or prostate cancer with no evidence of disease are eligible. Participants with multiple endocrine neoplasia type 2 (MEN2) associated pheochromocytoma may be eligible. * History of receiving any RET-inhibitor treatment * Are participants who are contraindicated for the use of selpercatinib * Are pregnant or intend to become pregnant or breastfeed during the study