Understanding a Clinical Trial Listing

Links to ClinicalTrials.gov often appear in peptide marketing as if a registry entry were proof of something. It is useful, but for a different reason: a listing tells you what a study set out to do and what became of it. This guide walks through the fields of a real listing, using two records we opened on October 18, 2026.

What a listing is, and what it is not

ClinicalTrials.gov is run by the National Library of Medicine. The study's sponsor or investigator supplies what each record says, and the library notes that being listed does not mean the federal government has evaluated a study ^{Source [1]}. A listing is a registration, not a review, an endorsement or a result.

Our two examples sit at opposite ends:

• STEP 1 (NCT03548935), a large semaglutide trial that finished, posted results and links to its journal paper ^{Source [2]}.
• PCO-02 (NCT02637284), a small study of BPC-157 tablets whose record has not been updated since 2015 ^{Source [3]}.

Field by field

NCT number and titles

Every registered study gets an identifier: "NCT" followed by eight digits ^{Source [4]}. Use it to match a paper, a press release or a sales page to the right record. Titles help less than you would hope. PCO-02's brief title does not name its active ingredient; only the official title says it is BPC-157 ^{Source [3]}.

Status

The overall status tells you where the study stands. Possible values include Not yet recruiting, Recruiting, Active not recruiting, Completed, Terminated, Withdrawn and Unknown status ^{Source [5]}. STEP 1 is Completed ^{Source [2]}.

PCO-02 shows "Unknown status." That label is applied when a study's last known status was not yet recruiting, recruiting, or active, its completion date has passed, and nobody has verified the record in the past two years ^{Source [4]}. PCO-02's last known status was "Active, not recruiting," its completion was estimated for March 2016, and its last update was posted on December 22, 2015 ^{Source [3]}. The record cannot tell you whether the study ran, stopped or produced any data.

Phase

Phases describe the stage of drug development. In the FDA's summary, phase 1 studies involve roughly 20 to 100 people and focus on safety; phase 2 studies involve up to several hundred and look at efficacy and side effects; phase 3 studies involve about 300 to 3,000 and are designed to show whether a treatment benefits a specific population. Phase 4 comes after approval ^{Source [6]}. STEP 1 is phase 3; PCO-02 is phase 1 ^{Source [2] Source [3]}. A phase 1 listing, even a completed one, is not evidence that a product works.

Design

The design fields show how fair the comparison was. Both records describe randomized studies with a placebo group and quadruple masking, meaning participants, care providers, investigators and outcome assessors did not know who received what ^{Source [2] Source [3]}. PCO-02 lists its primary purpose as "basic science," not treatment ^{Source [3]}.

Enrollment

Look for the word next to the number. STEP 1 reports an actual enrollment of 1,961 ^{Source [2]}. PCO-02 reports an estimated 42, the number it planned before starting ^{Source [3]}. An estimate tells you nothing about how many people were really studied.

Who was studied, and in what form

The eligibility and intervention sections tell you who took part and what they received. STEP 1 enrolled adults with overweight or obesity, who received semaglutide or placebo injections under the skin plus diet and physical activity counseling for 68 weeks ^{Source [2]}. PCO-02 planned to enroll healthy volunteers aged 18 to 35, who would take BPC-157 tablets or placebo tablets by mouth, in single-dose and repeated-dose parts ^{Source [3]}. A record about tablets says nothing about other forms or routes.

Outcomes

The primary outcome is the measure a study is built to answer; secondary outcomes are extras. STEP 1 lists two primary outcomes, both measured at week 68: the percent change in body weight and whether a participant lost at least 5 percent of body weight. It also lists 40 secondary outcomes ^{Source [2]}. PCO-02's primary outcome is adverse events over six months, with blood-level measurements as secondary outcomes ^{Source [3]}. A safety outcome in healthy volunteers cannot show benefit for any condition.

Sponsor

The lead sponsor is the organization that initiates the study and controls it ^{Source [4]}. STEP 1's sponsor is Novo Nordisk, which makes semaglutide ^{Source [2]}. PCO-02's sponsor is PharmaCotherapia d.o.o., with a hospital in Tijuana, Mexico, as collaborator and the only listed site ^{Source [3]}. Sponsorship is normal, but it tells you whose questions the study was designed to answer.

Dates and results

Four dates matter: when the record was first posted, when results were first posted, when the record was last updated, and the completion date. STEP 1 was first posted in June 2018, posted results in August 2021 and links to its main paper in the New England Journal of Medicine ^{Source [2] Source [7]}. PCO-02 has no posted results and no linked publications ^{Source [3]}.

Results posted and results published are different things

A record without posted results does not always mean no results exist. An ipamorelin trial for bowel function after surgery (NCT00672074) is listed as completed in 2009, has no results on the registry, and links to a journal article ^{Source [8]}. That 2014 paper reported no significant difference from placebo on its main measure ^{Source [9]}. Checking both places gave the full picture, including a negative result that a sales page would be unlikely to mention.

A quick checklist

• Match the NCT number to the claim you are checking.
• Read the status and the last-update date together.
• Note whether enrollment is actual or estimated.
• Check who was studied, and the form and route of what they received.
• Find the primary outcome and ask whether it matches the claim.
• Look for posted results and linked papers, and read them, not just the listing.

Our guide on how to read a peptide study covers the papers themselves. This page explains records; it is not medical advice, and we do not give dosing guidance.