Ask VialBase
Research

ALN-2232 Phase 1/2 in Obesity, Alone and Co-Initiated with Tirzepatide — VialBase Research

Trial Summary

Phase 1/2 trial evaluating ALN-2232 — an RNAi therapeutic from Alnylam Pharmaceuticals — as a new pharmacological approach to obesity, both as monotherapy and co-initiated with Tirzepatide. Alnylam’s hypothesis is that siRNA-based silencing of an obesity-relevant hepatic target can produce durable weight loss complementary to incretin therapy.

Design

  • Type: Three-part study (A: single ascending dose; B: multiple ascending doses; C: co-initiation with tirzepatide)
  • Population: Adults with obesity
  • Enrollment: 156 participants
  • Arms:
    • ALN-2232 single/multiple ascending doses
    • Placebo control
    • ALN-2232 + Tirzepatide co-initiation
  • Duration: Recruitment opened March 2026, estimated completion March 2028

Key Outcomes

Trial is recruiting; no results available yet.

  • Part A primary endpoint: frequency of adverse events (safety dose escalation)
  • Parts B & C primary endpoint: percent change in body weight from baseline

Significance for Peptide Research

This is an important trial for the broader obesity pharmacology landscape because it probes a new mechanism category — hepatic RNAi — as a layered-on therapy to incretin agonism rather than a replacement. Three signals to watch when results read out:

  1. Stackability with GLP-1/GIP agonists: if ALN-2232 + tirzepatide is additive or synergistic on weight loss without worsening GI tolerability, this establishes a combination pharmacology playbook for obesity that extends past single-pathway approaches.
  2. Durability: RNAi therapies typically have long pharmacodynamic tails (months per dose). If weight loss persists after tirzepatide discontinuation in a combination regimen, that’s a potential answer to the well-documented weight regain problem after GLP-1 discontinuation.
  3. Dose-response safety: Alnylam’s pipeline has seen clean safety profiles in other RNAi programs, so this trial’s AE frequency curve will shape investor and prescriber appetite for stacking RNAi on top of incretin therapy.

See Also