A Study of the Cardiac Effects of ALXN1840 in Healthy Adults

A Randomized, 3-Treatment, 3-Period, 6-Sequence, Crossover, Placebo- and Active-Controlled, Double-Blind for ALXN1840 (Open-Label for Moxifloxacin) Thorough QT/QTc Study to Evaluate ALXN1840 on Cardiac Repolarization in Healthy Adults

This study will evaluate the effect of a supratherapeutic dose of ALXN1840 on the heart rate (HR)-corrected QT interval (QTc) in healthy adult participants. Moxifloxacin will be used as the active control.

This is a randomized, 3-treatment, 3-period, 6-sequence, crossover, placebo- and active-controlled, double-blind for ALXN1840, open-label for moxifloxacin, in healthy adult participants. Participants will be domiciled in the clinic for 7 days during Treatment Period 1 and for 6 days during Treatment Period 2 and 3. A single oral dose of each treatment (ALXN1840, matching ALXN1840 placebo, or moxifloxacin) will be administered on Day 1 of each period following an overnight fast of at least 10 hours. There will be a minimum 14-day washout between study intervention administrations for each treatment period. Cardiodynamic, pharmacokinetic, and safety assessments will be performed at certain times during the study. An end-of-study visit will occur 14 days (±2 days) after the last dose.

Inclusion Criteria:

1. Nonsmoker.
2. Body weight at least 60 kilograms (kg) for males or 52 kg for females and body mass index ≥18.0 and ≤30.0 kg/meter squared.
3. Willing and able to follow protocol-specified contraception requirements.
4. Participant has no clinically significant history or presence of ECG findings.

Exclusion Criteria:

1. History or presence of clinical and/or lab disorders.
2. Lymphoma, leukemia, or any malignancy within the past 5 years, or breast cancer within the past 10 years.
3. Participant has abnormal blood pressure, defined as a supine blood pressure <90/50 millimeters of mercury (mm Hg) or >140/90 mm Hg.
4. Serum potassium, calcium, or magnesium levels outside the normal range.
5. Serum copper and/or ceruloplasmin values below the lower limit of normal at Screening.
6. Female participant has hemoglobin <10.8 grams/deciliter (g/dL) and male participant has hemoglobin <12.5 g/dL.
7. Clinically significant multiple or severe allergies.
8. Alanine aminotransferase, aspartate aminotransferase, serum creatinine, or total bilirubin greater than upper limit of normal (with the exception of Gilbert's syndrome).