Effects of Tucatinib on Cardiac Repolarization in Healthy Participants

This study will evaluate the effects of a steady state therapeutic dose of tucatinib on QTcF (QT interval corrected for heart rate using Fridericia's method) in healthy individuals. In this design, study treatment will be dosed in 3 sequential treatment periods:

Treatment A: Oral doses of 300mg tucatinib for 5 days

Treatment B: Oral doses of matching placebo for tucatinib for 5 days

Treatment C: A single oral dose of 400 mg of moxifloxacin

Patients will be randomized based on 2-Williams-square design to 1 of 6 treatment sequences to maintain the study blind for tucatinib and placebo.

Inclusion criteria

• Good health, determined by medical history, physical examination, 12-lead ECG, vital signs measurements, or clinical laboratory evaluations
• Body mass index (BMI) between 18 and 32 kg/m^2
• Body weight between 50 and 100 kg
• Female subjects must be of non-childbearing potential
• Male subjects must agree to use contraception or be surgically sterile for at least 90 days

Exclusion criteria

• Significant history of any metabolic, allergic, dermatological, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal, neurological, respiratory, endocrine, or psychiatric disorder
• Any condition affecting drug absorption
• History of hypersensitivity or allergy to any drug compound, food, or other substance
• Single 12-lead ECG demonstrating QTcF >450 msec for males or >470 msec for females, or history/evidence of long QT syndrome
• History of alcoholism or drug/chemical abuse within 2 years
• Use of prescription products within 30 days prior to check in
• Use of nonprescription products within 14 days prior to check in, including vitamins, minerals, and herbal supplements
• Use of tobacco- or nicotine-containing products within 3 months prior to check in