The principal aim of this study is to obtain safety and tolerability data when MRT-6160 is administered orally as single and multiple doses to healthy subjects. This information, together with the pharmacokinetic (PK) data, will help establish the doses and dosing regimen suitable for future studies in patients.

The study drug, MRT-6160, is experimental. This is the first study in which MRT-6160 will be given to humans.

Part 1: Subjects will receive a single oral dose of MRT-6160 or placebo on Day 1

Part 2: Subjects will receive multiple oral doses of MRT-6160 or placebo for 7 consecutive days

Detailed Description:

The purpose of this study is to:

Learn about the safety and tolerability of single and multiple ascending oral doses of MRT-6160 in healthy adult subjects

Inclusion Criteria:

• Healthy, adult, male or females 19-65 years of age
• Non smoker who has not used nicotine and tobacco containing products for at least 3 months prior to start of study
• Able to swallow oral medications
• Understands the study procedures in the informed consent form (ICF) and be willing and able to comply with the protocol

Exclusion Criteria:

• History or presence of clinically significant medical or psychiatric condition or disease that will interfere with adherence to study protocol
• Underwent surgical intervention or an operation within 4 weeks prior to start of study
• Has active TB, latent TB, a history of TB, or had close contact with a person with active TB within 8 weeks prior to the first dosing
• Female subject with a positive pregnancy test or who is lactating
• Positive urine drug or alcohol screen results
• Positive COVID-19 results indicating recent or current COVID-19
• Positive results for human immunodeficiency virus (HIV), hepatitis B or hepatitis C virus or history of resolved hepatitis
• Participation in another clinical study within 30 days or within 5 half-lives (if known) prior to start of study