A Study of Carbon-14-Labelled [14C] LOXO-305 (Pirtobrutinib) in Healthy Male Participants

A Phase I, Open-label, Two-part Study of the Absorption, Metabolism, Excretion, and the Absolute Bioavailability of [14C]-LOXO-305 in Healthy Male Subjects

The main purpose of this study is to evaluate the absorption, metabolism, and excretion (AME) profiles of pirtobrutinib (LOXO-305), to identify and characterize metabolites of pirtobrutinib (LOXO-305), and to assess the safety and tolerability of [14C] LOXO-305 in Part 1. To determine the absolute bioavailability of pirtobrutinib (LOXO-305), to evaluate the plasma concentration of total radioactivity, to evaluate the urinary excretion of [14C] LOXO-305 and total radioactivity, to evaluate the fecal excretion of [14C] LOXO-305 and total radioactivity, and to assess the safety and tolerability of pirtobrutinib (LOXO-305), and [14C] LOXO-305 in Part 2. Blood tests will be performed to check how much pirtobrutinib (LOXO-305) and [14C] LOXO-305 gets into the bloodstream and how long it takes the body to eliminate it.

The study will last up to approximately 60 days for Part 1 and approximately 47 days for Part 2.

Inclusion Criteria:

• Must have Body mass index (BMI) within the range of 18.5 to 32.0 kilograms per square meter (kg/m²), inclusive
• Male participants in good health, determined by no clinically significant findings from medical history, 12-lead Electrocardiogram (ECG), vital sign measurements, or clinical laboratory evaluations as assessed by the investigator
• Participants who are capable of fathering a child must agree to use contraception from the time of the dose administration through 6 months after the last dose of LOXO-305 administration
• History of a minimum of 1 bowel movement per day

Exclusion Criteria:

• History or presence of any diseases or conditions of clinical significance by the Investigator (or designee) and/or Sponsor
• Positive serologic test for hepatitis B surface antigen (HBsAg), hepatitis B virus (HBV) core antibody, hepatitis C virus (HCV) antibody, or human immunodeficiency virus (HIV) antibody at Screening
• Positive polymerase chain reaction (PCR) test for COVID-19 at Screening or Check-in (Day -1)
• Known ongoing alcohol and/or drug abuse within 2 years prior to Screening
• History of significant hypersensitivity, intolerance, or allergy to any drug compound, food, or other substance, unless approved by the Investigator (or designee)
• Part 1 only: Participation in a radiolabeled drug study where exposures are known to the Investigator (or designee) within the previous 4 months prior to Check-in (Day -1) or participation in a radiolabeled drug study where exposures are not known to the Investigator (or designee) within the previous 6 months prior to Check-in (Day -1).
• Part 2 only: Participation in any other radiolabeled investigational study drug trial within 12 months prior to Check-in (Day -1). Any previous radiolabeled study drug must have been received more than 12 months prior to Check-in (Day -1).