Alnylam Pharmaceuticals (Nasdaq: ALNY) has initiated a first-in-human Phase I trial of ALN-6222, an investigational siRNA therapeutic administered subcutaneously in adults with obesity — marking the company's latest attempt to apply its RNAi platform to metabolic disease beyond its established rare disease franchise.
The randomized, double-blind, placebo-controlled, single ascending dose study will enroll approximately 88 participants with a BMI of 30 to less than 40 kg/m² and an HbA1c below 6.5%, according to the trial record (NCT07624071). The HbA1c ceiling effectively excludes individuals with established type 2 diabetes, focusing the population on obesity without significant glycemic dysregulation. The trial is set to run through December 2027 at a site in Mount Royal, Canada, with endpoints focused on safety and pharmacodynamics.
The molecular target of ALN-6222 has not been disclosed in any publicly available source identified at the time of publication. Alnylam's obesity pipeline, as presented at its 2025 R&D Day, includes programs directed at inhibin subunit beta E (INHBE) in the liver and activin receptor type 1C (ACVR1C) in adipose tissue. The company's Q1 2026 investor materials separately identified ALN-2232 as the first adipose-directed RNAi program targeting ACVR1C to enter Phase I. ALN-6222 is a distinct compound; attributing any specific target to it from publicly available materials would be speculative.
As an siRNA, ALN-6222 would be expected to silence a specific messenger RNA, preventing translation of its encoded protein. The subcutaneous delivery route is consistent with Alnylam's established GalNAc-conjugate chemistry, which directs siRNA payloads to hepatocytes, though the company has also been developing adipose-directed delivery approaches. Whether ALN-6222 acts on a hepatic or peripheral target cannot be determined from available data.
The obesity pharmacology space has attracted significant RNAi investment, largely because the durability of siRNA-mediated gene silencing — potentially enabling monthly or quarterly dosing — offers a potential differentiation from the daily or weekly injectable GLP-1 receptor agonists that currently dominate the market.