How to read a research or regulatory signal

Prepared by: Research Desk. Sources are linked for verification.

Why this guide exists

KlowSignal reports new studies and regulatory updates on research peptides. A mouse study, a company announcement and an FDA meeting notice can all mention the same compound and still say very different things. This guide explains how we read each type of record. More about the site is on the about page.

Study types and levels of evidence

• Cell studies (in vitro). These show whether a compound can affect a pathway under controlled conditions. Birk et al. (2013) reported that SS-31 binds the mitochondrial lipid cardiolipin with high affinity. This describes a mechanism, not what happens in a whole organism.
• Animal studies (in vivo). Lee et al. (2015) reported effects of MOTS-c on insulin sensitivity in mice. Results in rodents often do not carry over to people, and work from a single laboratory needs independent replication.
• Observational human studies. These compare existing measures, such as natural blood levels of a peptide, across groups. They show associations, not cause and effect.
• Phase 1 trials. Usually small studies of safety, tolerability and how the body handles a compound.
• Phase 2 trials. Larger studies looking for an early sign of effect and gathering more safety data.
• Phase 3 trials. Large, usually randomised, placebo-controlled studies designed to confirm an effect. They can fail: MMPOWER-3, a phase 3 trial of elamipretide with 218 participants reported by Karaa et al. (2023), did not meet its primary endpoints.
• Systematic reviews. These gather and grade all studies on a question. Poolton et al. (2026) found three small human studies of BPC-157 with 30 participants in total and rated the certainty of evidence as very low.

A primary endpoint is the main outcome a trial is designed to test. Missing it means the trial did not show what it set out to measure.

Press release, peer-reviewed paper or registry entry

• Press release. Written by a company or institution, often the first word on a result such as "positive topline results". It is selective, usually lacks full methods and has not been independently checked.
• Peer-reviewed paper. Assessed by other researchers before publication and expected to report methods, numbers and limitations. Peer review is a filter, not a guarantee.
• Trial registry entry. A public record of a trial's design, planned outcomes and status. Comparing it with the final paper can reveal changed or unreported outcomes. It does not show that any result exists.

FDA vocabulary

• Approval. FDA has authorised one product, from one sponsor, for the use described in its label. It does not extend to other material containing a similar molecule.
• Accelerated approval. Approval based on an intermediate or surrogate endpoint, with a required confirmatory trial. As covered in our elamipretide article, FDA granted accelerated approval to Forzinity (elamipretide) for Barth syndrome on 19 September 2025, based on knee extensor muscle strength. Research-grade SS-31 is not that product.
• 503A bulks list. Bulk drug substances that pharmacies compounding under section 503A may use. Being considered for the list is not being on it.
• Category 2. Under FDA's interim policies, nominated substances that may present significant safety risks are placed in category 2, with the section concerned, the date added and the risks identified.
• Nominated but withdrawn. The same page lists substances previously in category 2 whose nominations were withdrawn, including AOD-9604, BPC-157 and TB-500. For BPC-157, FDA noted possible immunogenicity, peptide-related impurities and no, or only limited, safety-related information. Withdrawal is not a finding of safety.
• Pharmacy Compounding Advisory Committee (PCAC). An expert committee that advises FDA; FDA decides. The July 23–24, 2026 meeting page lists BPC-157, KPV, TB-500, MOTs-C, emideltide (DSIP), Semax and Epitalon as being considered for the 503A bulks list, with the uses FDA reviewed, such as ulcerative colitis for BPC-157. Uses evaluated are not established effects. See our meeting coverage.

What research-use-only labelling means

A research-use-only (RUO) label means a material is sold as a laboratory reagent for non-clinical research. It is not a medicine, has not been evaluated or approved by FDA, and is not intended for human or animal use. The label says nothing about whether a compound works. For laboratories the key questions are identity and purity, and batch-level certificates of analysis are the minimum documentation to expect.

Checklist for each signal

Supplier

Purita is a store that sells peptides for laboratory research use only, and its product pages label items for research use only and not for human or animal administration.

Visit the Purita website

Affiliate disclosure: this is a paid link. KlowSignal earns a commission if a purchase is made through it, at no extra cost to the buyer. A listing is not an endorsement or a statement about product quality. See the affiliate disclosure.

Related pages

• Research peptide signals: studies and regulatory updates
• About KlowSignal
• FDA compounding committee, July 2026: seven research peptides on the agenda
• Elamipretide (SS-31): the 2025 accelerated approval on the record