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Is PIONEER-1 a fair comparison of oral semaglutide against its comparator arm?

Asked 23 Mar 2024Modified 2.0 years agoViewed 46k times
26

Details up front: PIONEER-1 · oral semaglutide.

I am asking for verification rather than opinion, ideally with something I can read myself.

It is possible the evidence exists and I am searching for the wrong term.

What would count as evidence here, and does it exist?

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RH
askedrania_haddad13k2723 Mar 2024

5 Answers

Accepted answer first, then by votes
-3

Accepted answer

Fair depends on the comparator arm, and in PIONEER-1 that means asking whether the comparator was titrated to the same ambition as the experimental one. A head-to-head that runs its comparator to a dose below the one it is licensed at is not measuring the two agents, it is measuring one agent against a handicapped version of the other. Check three things: the maximum comparator dose reached, the proportion of the comparator arm that reached it, and whether the titration schedules had the same duration. If those match, the comparison is fair on dosing and the argument moves to the endpoint. If they do not, the effect size is partly an artefact of the protocol.

It helps to be literal here: a trial establishes what happened to a defined group under a defined protocol. Extending it beyond that group is inference, and inference is allowed as long as it is labelled.

Confidence intervals matter more than point estimates when two trials disagree. Two studies reporting fifteen and twenty per cent whose intervals overlap heavily have not disagreed about anything.

More usefully, non-inferiority and superiority designs are not interchangeable. A non-inferiority result says the new agent is not meaningfully worse against a pre-specified margin — it does not say it is as good, and it certainly does not say it is better.

The cardiovascular outcome programme in this class runs to several large randomised trials — LEADER for liraglutide, SUSTAIN-6 and SELECT for semaglutide, REWIND for dulaglutide — and they are the reason the class is discussed as more than a weight intervention.

Read the protocol and the statistical analysis plan if the result matters to you. Both are usually published alongside.

edited 28 Jul 2024 by Dr_Tomas_Kral — clarified the distinction between purity and content

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DK
answered · acceptedDr_Tomas_Kral53k389 Jul 2024
Good answer, but the confidence interval in the cited trial is wider than implied. – Dr_Tomas_Kral 30 days ago
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42

The trial answers a narrower question than the headline suggests, and the narrowing is where the useful information is.

Intention-to-treat and per-protocol analyses answer different questions. ITT asks what happens if you offer the treatment; per-protocol asks what happens if it is taken as directed. The gap between the two is a measure of how tolerable the protocol was.

Mechanically, trial populations are selected. Exclusion criteria in this class routinely remove people with significant renal impairment, prior pancreatitis and unstable psychiatric illness, which is exactly the population the results are then quoted for.

Where a result is quoted from a conference abstract rather than a peer-reviewed publication, the numbers routinely move between the two. It is worth checking which one you are reading.

Be careful about generalising from a trial population to yourself. The exclusion criteria are usually the most informative page in the supplement.

The short version: check the endpoint, check the comparator, check who was excluded, then look at the number.

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LC
answeredlyoph_cake78k26728 Jun 2024
4This should be linked from the help pages. – tadhg_o_riordan 4 months ago
5Absolute risk reduction rather than relative would make this much more useful. – Dr_Wren_Halliday 6 months ago
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33

Start with what the trial was powered for. Everything else in the publication is secondary, exploratory, or a subgroup, and those three words mean three different things.

Duration decides what can be seen. A 68-week trial can measure weight and glycaemia; it cannot measure anything whose event rate is one per cent per year without enrolling tens of thousands.

A composite endpoint is only as informative as its least serious component. Where a cardiovascular composite combines death, infarction and stroke, ask which component moved, because they are not interchangeable outcomes.

If a claim cannot be traced to a named trial with a named endpoint, treat it as a claim rather than as evidence.

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RS
answeredrota_site36k273 Apr 2024
27

The honest answer here is that the published evidence supports part of the claim and is silent on the rest, and it is worth being precise about which part is which.

Placebo arms in this class are not nothing. Lifestyle-intervention placebo arms in the major obesity trials commonly lose two to three per cent of body weight, so an active-arm figure quoted without its comparator overstates the drug effect by roughly that much.

One qualification: absence of a signal in a trial of this size is not evidence of absence for a rare event. It is evidence that the event is rarer than the trial could detect.

When two sources disagree, the answer is almost always in the methods section of the one you have not read.

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DV
answeredDr_Ilse_Vandenberg113k24821 Jul 2024
23

Answer first: read the primary endpoint, the comparator and the population before you read the effect size. Almost every argument on this site about a trial is really an argument about one of those three.

Open-label extensions are not the same evidence as the randomised phase. Once everyone knows what they are taking, the reported outcomes acquire a bias that no analysis fully removes.

Quote the interval alongside the estimate and half the disagreements on this site would not start.

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P9
answeredplate_count_9k78k24826 May 2024

Your answer

Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.

Not medical advice. Research-use-only compounds are not approved for human use.