A Trial to Learn if ALN-PNP is Safe and Well Tolerated in Healthy Adults and Adult Participants With Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)
Trial Parameters
Brief Summary
This study is researching an experimental drug called ALN-PNP (called "study drug"). This is a first in human study. The study drug is not approved by any public health agency such as the United States Food and Drug Administration (FDA) for any kind of treatment. This study consists of 3 parts. Part A is focused on healthy participants. Parts B and C of the study are focused on participants who are known to have MASLD and a specific variant of the PNPLA3 gene. The aim of the study is to see how safe, tolerable and effective the study drug is. The study is looking at several other research questions, including: * What side effects may happen from taking the study drug (Parts A, B and C) * How much study drug (Parts A, B and C) and study drug metabolites (byproduct of the body breaking down the study drug) (Parts B and C) are in the blood at different times * Whether the body makes antibodies against the study drug (which could make the study drug less effective or could lead to side effects) (Part A, B and C) * Explore impact of Japanese ethnicity on safety and PK (Pharmacokinetics, or study of what the body does to the drug) of single doses of ALN-PNP over time (Part A) * How the study drug works to change liver fat content in MASLD (Part B and C) * Better understanding of the study drug and MASLD (Part B and C)
Eligibility Criteria
Key Inclusion Criteria: Part A (Healthy Adults): 1. From 18 to 55 years of age 2. For Japanese cohorts ONLY; the Japanese participant must: 1. Be Japanese, born in Japan, and have both biologic parents and 4 biologic grandparents who are ethnically Japanese and born in Japan 2. Have maintained a Japanese lifestyle, with no significant change since leaving Japan, including having access to Japanese food and adhering to a Japanese diet 3. Be living \<10 years outside of Japan 3. Has a body mass index between 18 and 32 kg/m\^2, inclusive, at the screening visit 4. Is judged by the investigator to be in good health, as described in the protocol 5. Is in good health based on laboratory safety testing obtained at the screening visit and approximately within 24 hours prior to administration of study drug Part B and Part C (Participants with MASLD): 1. Part B: From 18 to 65 years of age 2. Part C: From 18 to 75 years of age 3. Body mass index (BMI) from 23.0 kg/m2 to 40.0 kg/m2, inclusive, for