The main purpose of this study is to compare the amount of selpercatinib that gets into the blood stream and how long it takes the body to get rid of it, when given as different formulations. The information about any adverse effects experienced will be collected and the tolerability of selpercatinib will also be evaluated. The study may last up to 56 days including the 28 days of screening period.

Inclusion Criteria:

• Participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, and vital signs.
• Participants who have clinical laboratory test results within the normal reference range for the population or investigative site, or results with acceptable deviations that are judged to be not clinically significant by the investigator.

Exclusion Criteria:

• Have a history of allergic reactions to medications or food products
• Have a clinically significant abnormality of blood pressure and/or pulse rate as determined by the investigator
• Clinically significant abnormalities on ECG as determined by the investigator or prolongation of the QTcB or QTcF >450 msec at screening
• Have clinically significant active cardiovascular disease or history of myocardial infarction within 6 months prior to the planned start of selpercatinib
• Have a history or presence of cardiovascular, respiratory, renal, gastrointestinal, endocrine, hematological, or neurological disorders capable of significantly altering the absorption, metabolism, or elimination of drugs; of constituting a risk when taking the investigational product; or of interfering with the interpretation of data. Appendectomy, splenectomy, and cholecystectomy are considered as acceptable
• Use of H2 blockers, proton pump inhibitors, and other drugs that affect selpercatinib exposure within 7 days of screening
• Are intending to use over-the-counter or prescription medication, including dietary supplements, within 14 days prior to dosing and until study discharge (apart from occasional acetaminophen (≤2 g/24 hours), hormonal contraception, or hormone replacement therapy)

All enrolled participants.

Baseline up to 28 days

All enrolled participants who received at least one dose of selpercatinib, whether or not they completed all protocol requirements, and have at least one postdose safety assessment.