QRL-101-03 is a multiple ascending dose (MAD) study to evaluate the safety, tolerability, and pharmacokinetics (PK) of QRL-101 in healthy participants. QRL-101-03 is a follow-on study to QRL-101-01, an ongoing Phase 1, single ascending dose study to determine the safety, tolerability, and PK profile of QRL-101 after a single dose (ClinicalTrials.gov ID: NCT05667779).

Phase 1, single-site, multiple-dose study to evaluate the safety, tolerability, and PK of multiple ascending doses of QRL-101 in healthy participants. Up to 5 cohorts of 8 participants each, randomized 6:2 (QRL-101: placebo) will be tested. The approximate total duration of study participation for each participant may be up to 39 days.

Inclusion Criteria:

1. Age 18 to 70 years of age inclusive at the time of signing the informed consent.
2. Clinical chemistry laboratory values within acceptable range for the population, as per investigator judgment.
3. Body mass index of 18 to 32 kg/m2 (inclusive).
4. Willing and able to practice effective contraception.

Exclusion Criteria:

1. Currently enrolled in any other clinical trial involving a study drug or off-label use of a drug or device, or any other type of medical research judged not to be scientifically or medically compatible with this study.
2. Any participant in >4 studies a year and/or has participated in a clinical trial within 1 month of expected dosing date.
3. History or presence of medical illness including, but not limited to, any cardiovascular, hepatic, respiratory, hematological, endocrine, psychiatric, or neurological disease, convulsions, or any clinically significant laboratory abnormality that, in the judgment of the investigator, indicate a medical problem that would preclude study participation.

A participant and investigator-blinded, randomized, placebo-controlled design will be used to minimize bias in this study.