This was a Phase 1, placebo-controlled, randomized, double-blind (participant and investigator blind, sponsor open), multiple-ascending dose study conducted in healthy participants to demonstrate the safety and tolerability and to evaluate the pharmacokinetics and pharmacodynamics of ACH-0145228 (ALXN2050).

Key Inclusion Criteria:

• Was overtly healthy as determined by medical evaluation including detailed medical history, physical examination, blood pressure and heart rate measurements, 12-lead ECG, and clinical laboratory tests.
• Had a body weight of at least 50 kilograms (kg) and body mass index within the range of 18 to 30 kg/meter squared (inclusive).
• Male participants were eligible to participate if they agreed to abstinence or use of a highly effective method of contraception.
• Female participants must have been of nonchildbearing potential.

Key Exclusion Criteria:

• Had a history or clinically relevant evidence of current cardiovascular, pulmonary, hepatic, renal, hematological, gastrointestinal, endocrine, immunologic, dermatologic, neurological, or psychiatric disorders or conditions capable of significantly altering the absorption, metabolism, or elimination of drugs; constituting a risk when taking the study intervention; or interfering with the interpretation of data.
• Had a body temperature greater than or equal to 38°Celsius on Day -1 or Day 1, Hour 0; had a history of febrile illness, or other evidence of infection, within 14 days prior to first study drug administration.
• Had a sensitivity to any of the study interventions, or components thereof, or drug or other allergy that contraindicated participation in the study.
• Donated blood or lost more than 500 milliliters of blood within 3 months prior to first study drug administration, or received a blood transfusion or blood products within 6 months prior to first study drug administration.
• Current enrollment or past participation within the last 30 days before study drug administration in any clinical study involving an investigational study intervention or any other type of medical research
• Had clinically significant laboratory abnormalities.
• Positive urine drug screen at Screening or Day -1; was a current tobacco/nicotine user or smoker; consumed any alcohol within 72 hours before first study drug administration or had a history of regular alcohol consumption within 6 months of screening.