PET Study of PIPE-791 in Healthy Volunteers and Volunteers With PrMS and IPF

Main Inclusion Criteria * All parts: male volunteers or female volunteers of non-childbearing potential; agree to follow the contraception requirements of the trial, and able to give fully informed written consent. * Part A: normotensive volunteers, deemed healthy on the basis of a clinical history, medical examinations, ECG, vital signs, and laboratory tests of blood and urine. * Part B: volunteers with a diagnosis of PPMS or SPMS by a neurologist, according to the 2017 Revised McDonald Criteria. * Part C: volunteers with a diagnosis of IPF by a pulmonologist, according to the 2018 American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society (JRS)/Latin American Thoracic Society (ALAT) Clinical Practice Guideline, within 7 years before screening. Main Exclusion Criteria * Positive tests for hepatitis B and C, human immunodeficiency virus (HIV) * Severe adverse reaction to any drug; sensitivity to trial medication * Drug or alcohol abuse * Smoking or use of tobacco or nicotine-containing products from 7 days before screening, until the final visit * Use of a prescription medicine (except hormone replacement therapy \[HRT\] in women, and medications for participants with PrMS and IPF at the discretion of the investigator), or any substance known to interact with cytochrome p450 (CYP)3A enzymes (including St. John's wort and foodstuffs such as grapefruit juice) during the 28 days before the first dose of PIPE-791 * Use of any other over-the…