PF-08653944
InvestigationalPfizer's once-monthly GLP-1 receptor agonist peptide (Metsera MET097 lineage). The once-monthly Phase 2b (SOLIS-1, NCT07575932) is recruiting with no reported results yet, and the molecule has no published efficacy data. A Phase 3 program (VESPER-4/5/6) is enrolling, positioning it as a potential long-acting alternative to weekly GLP-1 therapies.
Pfizer GLP-1 · Monthly GLP-1
5 human studies
- Preclinical
- 38%
- Human research
- 63%
Based on 8 cited sources
Numeric assessment unreviewed
A historical numeric score is recorded but has not passed a current, compound-specific assessment review. No numeric score is displayed.
This is a limitation of the numeric assessment, not a measured absence of benefit. It does not re-review the separately recorded catalogue classification or establish efficacy or safety.
How It Works (Simplified)
PF-08653944 is a long-acting GLP-1 receptor agonist designed for once-monthly subcutaneous administration. Like other GLP-1 receptor agonists, it mimics the incretin hormone GLP-1 to reduce appetite, slow gastric emptying, and improve glycemic control. The monthly dosing interval represents a significant advancement over current weekly injectable options.
Scientific Pathways
GLP-1 Receptor Activation: Binds to and activates the GLP-1 receptor, enhancing glucose-dependent insulin secretion, suppressing glucagon release, delaying gastric emptying, and activating central satiety pathways in the hypothalamus.
Extended Duration: Pfizer’s proprietary formulation technology enables sustained GLP-1 receptor engagement over approximately 30 days from a single injection, potentially improving treatment adherence compared to weekly alternatives.
Clinical Evidence
No published efficacy data. PF-08653944 has zero PubMed-indexed publications and no posted ClinicalTrials.gov results. No human weight-loss figure for the once-monthly molecule has been reported, so any specific percentage should be treated as unverified.
Once-monthly Phase 2b (ongoing): The dedicated Phase 2b dose-finding study for once-monthly PF-08653944 — SOLIS-1 (NCT07575932), an umbrella study also evaluating the amylin analog PF-08653945 — is recruiting, with its primary body-weight endpoint at Week 48 and no results yet.
Weekly MET097 lineage: PF-08653944 is the once-monthly formulation of Metsera/Pfizer’s MET097 (a fully-biased, ultra-long-acting GLP-1 receptor agonist). The once-weekly MET097 has completed earlier-stage trials, including a Phase 1/2 study (NCT06857617) and a 28-week Phase 2b (VESPER-1, NCT06712836) — but these test the weekly formulation, and neither has posted results on ClinicalTrials.gov.
Phase 3 program (ongoing): A Phase 3 program is now enrolling, including VESPER-5 in type 2 diabetes (NCT07400653), VESPER-6 in overweight/obesity (NCT07595549), and VESPER-4 (NCT07311850). These trials are recruiting; none has reported results.
Safety Profile
No trial-reported safety data have been posted for once-monthly PF-08653944. Based on the GLP-1 class, the expected adverse event profile is gastrointestinal — nausea, vomiting, and diarrhea. Monthly dosing may produce a different temporal pattern of side effects compared with weekly formulations, but this remains a hypothesis until the ongoing Phase 2b and Phase 3 trials report. Full safety characterization awaits those data.
Important Limitations
- No published or trial-reported efficacy data for once-monthly PF-08653944; any specific weight-loss percentage is unverified
- The dedicated Phase 2b (SOLIS-1) is still recruiting; Phase 3 trials are enrolling but have not reported results
- Monthly injection may limit dose titration flexibility
- Not available outside clinical trials
- Pfizer’s previous oral GLP-1 candidate (danuglipron) was discontinued, raising execution questions
Semaglutide
AvoidBoth are GLP-1 receptor agonists. Co-administration would provide redundant GLP-1 agonism with increased risk of GI adverse events.
Tirzepatide
AvoidBoth target GLP-1 receptors. Combining would create overlapping mechanisms with potential for severe GI side effects.
Research Note: Interaction data is based on published literature, mechanistic understanding, and theoretical considerations. Most peptide combinations lack direct clinical study. This information is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare providers.
Use the source links in the research discussion above to inspect the referenced records.
This dossier synthesizes available evidence from peer-reviewed literature, regulatory documents, and clinical trial registries. Evidence strength labels summarize the cited material for this entry and should be read alongside its population, model, and study limitations.
For complete methodology details, see our Methodology page.
Important Disclaimer
This dossier is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making health decisions.
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