Digestive & weight Oral α4β7 integrin antagonist peptide
PN-943
Regulatory status
Status at a glance
503A compounding status
Not nominated
We found no pending nomination for the 503A bulks list. Unless the substance has another legal pathway (for example, a USP monograph or use in an FDA-approved drug), 503A pharmacies generally may not compound with it.
- FDA approval
- Not FDA-approved for any use
- 503B outsourcing
- Not determined
- Anti-doping (WADA)
- Not on the WADA Prohibited List
- DEA schedule
- Not a controlled substance
About peptide status
Most peptides discussed here are not FDA-approved for any use, and products labeled “research use only” are not for human use. Removal from Category 2 does not authorize compounding. PCAC votes are non-binding recommendations; FDA and HHS make the final decisions.
This is not medical or legal advice, and we do not publish dosing, sourcing or reconstitution information. Talk with a licensed clinician before using any peptide.
If you think you are having a medical emergency, call 911.
Key takeaway
PN-943 is an investigational oral peptide that blocks the α4β7 integrin, the same gut-homing target as the antibody vedolizumab, developed by Protagonist Therapeutics for ulcerative colitis. Its earliest controlled trial missed its primary endpoint, and a later Phase 2 reported only a partial, internally inconsistent signal. As of 2026 it is not approved and the program is inactive.
At a glance
- FDA status
- Investigational peptide, not approved by the FDA
- What it is
- Oral α4β7 integrin antagonist studied for ulcerative colitis
- Research
- First controlled trial missed its primary endpoint
- Development status
- Later Phase 2 showed a mixed signal, and the program is inactive
- Evidence strength
- Low research
Summary
PN-943 is an investigational oral peptide that blocks the alpha4beta7 integrin in ulcerative colitis. See how it works and why the research is weak.
What is PN-943?
PN-943 is an experimental peptide taken by mouth, designed to act locally in the gut, developed by Protagonist Therapeutics for moderate-to-severe ulcerative colitis, an inflammatory bowel disease. It blocks the α4β7 integrin, the same pathway targeted by the approved injectable antibody vedolizumab, but as an oral peptide. It is investigational and not approved.
How does it work?
PN-943 blocks the α4β7 integrin on immune cells (lymphocytes), preventing it from binding its partner MAdCAM-1 on blood vessels in the gut. That interaction is how certain inflammatory T-cells "home" to the intestinal lining, so blocking it is intended to reduce the gut inflammation that drives ulcerative colitis. Delivering this as a gut-targeted oral peptide is the distinguishing idea. This describes the mechanism, separate from the trial outcomes below.
Is it FDA-approved?
Safety note
Status: Investigational peptide, not approved by the FDA
Category: In clinical trials · Primary body area: Digestive & weight
No. PN-943 is investigational and not approved. According to company disclosures, after its Phase 2 readout:
- Protagonist indicated the drug would need an external partner to advance
- No Phase 3 has started
- The company's focus shifted to other programs
What does the research show?
Editor’s note
Evidence strength: Low research (2 human · 0 animal/cell studies)
The only peer-reviewed controlled trial missed its primary endpoint, and the later signal is company-reported and internally inconsistent, with no Phase 3 under way.
The controlled evidence is weak, as the two trials show:
| Trial | Source | Result |
|---|---|---|
| Earlier Phase 2a study of the molecule, then called PTG-100 | Peer-reviewed, indexed on PubMed | Missed its pre-specified primary endpoint; a positive signal appeared only on a blinded re-read of endoscopy images at lower doses |
| Subsequent Phase 2 IDEAL trial | Company-reported, not peer-reviewed | Remission signal at the lower dose but not the higher dose, an inconsistent dose-response |
No Phase 3 has advanced, so efficacy is not established.
Sources: the Phase 2a trial of the molecule as PTG-100 (Sandborn et al., Gastroenterology, 2021, DOI: 10.1053/j.gastro.2021.08.045), indexed on PubMed; and Protagonist Therapeutics disclosures of the Phase 2 IDEAL results. This document is educational, is not medical advice or a health claim, and is not an offer to sell any product.
Registered human trials
2 registered human trials on ClinicalTrials.gov that we reviewed
Compare every peptide’s status in the peptide regulatory status database
More for Digestive & weight
View all digestive & weight peptides →- Not FDA-approved Digestive & weight
5-Amino-1MQ
5-Amino-1MQ is a small-molecule NNMT inhibitor that, in cell studies, increases NAD+ and SAM and suppresses fat production in fat cells. In diet-induced obese mice, a potent NNMT inhibitor reduced body weight and fat mass without changing food intake. As of 2026, no human trials have been published, and it is not a peptide. It is not approved by the FDA.
- In clinical trials Digestive & weight
Amycretin
Amycretin is an investigational single-molecule drug that activates both the GLP-1 receptor and the amylin receptor, being developed by Novo Nordisk in subcutaneous and oral forms for weight management. In a 2025 phase 1b/2a trial of 125 adults with overweight or obesity, the 60 mg group lost 24.3% of body weight at 36 weeks versus 1.1% on placebo (p < 0.0001), though many participants withdrew. As of 2026 it is not approved anywhere and is moving into Phase 3 testing.
- Not FDA-approved Digestive & weight
Aod-9604
AOD-9604 is a modified fragment of the tail end of human growth hormone, developed as a fat-loss drug. Its human obesity trials failed to beat placebo, and development for obesity was halted. As of 2026 it is not FDA-approved and is banned in sport.
- In clinical trials Digestive & weight
Apraglutide
Apraglutide is an investigational long-acting GLP-2 analog, developed by Ironwood Pharmaceuticals as a once-weekly injection for short bowel syndrome, a condition in which people depend on intravenous nutrition because their intestine cannot absorb enough. In a Phase 3 trial it reduced the need for that intravenous support compared with placebo. As of 2026 it is not approved, and the FDA has asked for an additional confirmatory trial.
- Not FDA-approved Digestive & weight
Bpc-157
BPC-157 is a synthetic 15-amino-acid peptide studied for tissue and gut repair, and 35 of the 36 studies in a 2025 systematic review were animal or lab work. The one human report, a retrospective series of 12 patients with chronic knee pain, found that seven (58%) described relief lasting more than 6 months. It had no control group, effect size, or safety data. BPC-157 is not FDA-approved, is prohibited in sport, and remains unsettled in FDA compounding review.
- In clinical trials Digestive & weight
Brilacidin
Brilacidin is an investigational defensin-mimetic, a small molecule designed to imitate the body's own host-defense peptides, developed by Innovation Pharmaceuticals for oral mucositis and studied as an antibacterial and antiviral agent. Its human results to date have been reported mainly through company announcements rather than peer-reviewed trials, while published support is largely laboratory-based. As of 2026 it is not approved for any use.