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Compounds · Retatrutide

Retatrutide dose escalation in the published trials

RM
r.mensaTL2 Moderator8 Mar 2025#1

Posting this under the heading it deserves: Retatrutide dose escalation in the published trials Everything below is what sits behind that.

Session topic: SURPASS-2 (N Engl J Med, 2021). Please read it before posting; the discussion is much better when everyone has.

The question I would like us to start with is what the trial set out to estimate, rather than what it found. Once that is on the table we can talk about whether the design could have answered it, and only then about the numbers.

Specific things I would like covered: the population and how far it generalises, how discontinuation was handled, whether the comparator was a fair one, and what the absolute rather than relative effect looks like.

I will summarise at the end and the summary will feed the relevant digest page.

3 likes 17mo
CC
c.castellanosTL2 Moderator9 Mar 2025#2

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.

7 likes 17mo
YM
y.mensahTL3Wiki editor10 Mar 2025#3

Hepatic effects: glucagon receptor agonism promotes hepatic fat oxidation, which is mechanistically plausible for benefit in metabolic liver disease. Whether that translates to improved clinical outcomes is being tested in phase 2 work.

24 likes 17mo
RM
r.mensahTL2 Moderator10 Mar 2025#4

How to read phase 2 without treating it as phase 3: phase 2 establishes that a dose range produces an effect and is tolerable enough to justify large trials. It does not establish safety, durability, or whether real humans differ from the selected population.

0 likes 17mo
JW
journalclub_wrenTL3Regular11 Mar 2025#5

Phase 2 sample sizes are not adequate for safety characterisation of a novel triple agonist. Phase 3 is where that question gets answered. Using phase 2 results to make claims about safety profile is using the trial for a purpose it was not designed for.

3 likes 17mo
YA
y.asanteTL2 Moderator11 Mar 2025#6
r.mensah, post #4: How to read phase 2 without treating it as phase 3: phase 2 establishes that a dose range produces an effect and is tolerable enough to justify large trials. It does not establish safety, durability, or whether real humans differ from the selected population. Go to post

Retatrutide is investigational. Anything obtained outside a trial is by definition research-use-only material with no human-use authorisation. This site will state that plainly rather than winking at it.

11 likes in reply to #4 17mo
SS
steady_stateTL312 Mar 2025#7
TK
t.karlsenTL2 Moderator12 Mar 2025 · edited#8

Coming back to post #6, because the follow-up matters more than the original answer.

TRIUMPH is phase 3 and it is ongoing. No phase 3 results exist. Nothing should be attributed to TRIUMPH because the trial has not finished. When it does, this page will update.

0 likes 17mo
NA
n.abernathyTL3Analytical chemist13 Mar 2025#9
r.mensa, post #1: Posting this under the heading it deserves: Retatrutide dose escalation in the published trials Everything below is what sits behind that. Session topic: SURPASS-2 ( N Engl J Med , 2021). Please read it before posting; the discussion is much better when everyone has. The question I would like us to start with is what the trial set out… Go to post

Triple agonism: is the effect additive, synergistic, or neither? A phase 2 comparison of tirzepatide (dual) to retatrutide (triple) would answer that question. The published data does not include such a direct comparison.

6 likes in reply to #1 17mo
PM
p.mwangiTL2 Moderator13 Mar 2025#10

Dose escalation in the published trials: the protocols started at lower doses and escalated by defined steps. The step sizes are documented and they may or may not match what someone self-prescribing would choose.

17 likes 17mo
TI
trough_indexTL3Regular13 Mar 2025#11
n.abernathy, post #9: Triple agonism: is the effect additive, synergistic, or neither? A phase 2 comparison of tirzepatide (dual) to retatrutide (triple) would answer that question. The published data does not include such a direct comparison. Go to post

Why this subcategory is more cautious than elsewhere: retatrutide is investigational, phase 3 is ongoing, and the heart-rate signal in phase 2 is not negligible. Caution is proportionate to the evidence status.

0 likes in reply to #9 17mo
AN
a.norgaardTL2 Moderator14 Mar 2025#12

This follows post #9 rather than contradicting it.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

0 likes 16mo
BR
buffer_reviewTL3Regular14 Mar 2025#13

Mass and identity: a report on retatrutide should state the mass detected by LC-MS, not assume a theoretical mass. The theoretical mass is not published in peer-reviewed literature for retatrutide at present.

18 likes 16mo
AC
a.cardosoTL2 Moderator14 Mar 2025 · edited#14
y.mensah, post #3: Hepatic effects: glucagon receptor agonism promotes hepatic fat oxidation, which is mechanistically plausible for benefit in metabolic liver disease. Whether that translates to improved clinical outcomes is being tested in phase 2 work. Go to post

The phase 2 obesity paper reported dose-dependent weight reduction of a magnitude that attracted attention. It also reported dose-dependent heart-rate increases. The heart-rate signal is the reason phase 3 exists rather than something assumed negligible based on phase 2.

7 likes in reply to #3 16mo
L
LJankowiakTL3Regular15 Mar 2025#15

Coming back to post #13, because the follow-up matters more than the original answer.

Glucagon receptor agonism seems paradoxical in a weight-loss compound because glucagon raises blood glucose. The paradox resolves because glucagon agonism also increases energy expenditure and promotes hepatic fat oxidation, and the incretin components offset the glycaemic effect. In diabetes trials, HbA1c improved rather than worsened.

1 like 16mo
MA
mi.amankwahTL2 Moderator15 Mar 2025#16

Picking up post #13: that is the part I would want checked first.

Why this subcategory is more cautious than elsewhere: retatrutide is investigational, phase 3 is ongoing, and the heart-rate signal in phase 2 is not negligible. Caution is proportionate to the evidence status.

0 likes 16mo
AD
ambient_draftTL3Regular15 Mar 2025#17

Dose escalation in the published trials: the protocols started at lower doses and escalated by defined steps. The step sizes are documented and they may or may not match what someone self-prescribing would choose.

24 likes 16mo
AK
ak.kravchenkoTL2 Moderator16 Mar 2025#18
journalclub_wren, post #5: Phase 2 sample sizes are not adequate for safety characterisation of a novel triple agonist. Phase 3 is where that question gets answered. Using phase 2 results to make claims about safety profile is using the trial for a purpose it was not designed for. Go to post

Triple agonism: is the effect additive, synergistic, or neither? A phase 2 comparison of tirzepatide (dual) to retatrutide (triple) would answer that question. The published data does not include such a direct comparison.

11 likes in reply to #5 16mo
JS
j.steinerTL2 Moderator16 Mar 2025#19

Glucagon receptor agonism seems paradoxical in a weight-loss compound because glucagon raises blood glucose. The paradox resolves because glucagon agonism also increases energy expenditure and promotes hepatic fat oxidation, and the incretin components offset the glycaemic effect. In diabetes trials, HbA1c improved rather than worsened.

3 likes 16mo
NM
n.moreauTL2 Moderator17 Mar 2025#20

What we do not know about retatrutide, listed explicitly: long-term safety, real-world response rates, the dose response in diverse populations, whether the heart-rate signal persists or attenuates, durability of effect on withdrawal, efficacy in comorbidities beyond obesity.

0 likes 16mo
IA
id.almeidaTL2 Moderator17 Mar 2025#21
LJankowiak, post #15: Coming back to post #13, because the follow-up matters more than the original answer. Glucagon receptor agonism seems paradoxical in a weight-loss compound because glucagon raises blood glucose. The paradox resolves because glucagon agonism also increases energy expenditure and promotes hepatic fat oxidation, and the incretin components… Go to post

Mass and identity: a report on retatrutide should state the mass detected by LC-MS, not assume a theoretical mass. The theoretical mass is not published in peer-reviewed literature for retatrutide at present.

1 like in reply to #15 16mo
BV
bias_varianceTL4Biostatistician17 Mar 2025#22

Hepatic effects: glucagon receptor agonism promotes hepatic fat oxidation, which is mechanistically plausible for benefit in metabolic liver disease. Whether that translates to improved clinical outcomes is being tested in phase 2 work.

6 likes 16mo
NK
n.krastevTL2 Moderator18 Mar 2025#23

post #22 is right about the mechanism and I think understates the practical bit.

How to read phase 2 without treating it as phase 3: phase 2 establishes that a dose range produces an effect and is tolerable enough to justify large trials. It does not establish safety, durability, or whether real humans differ from the selected population.

22 likes 16mo
BD
baseline_driftTL2Analytical chemist18 Mar 2025#24

Worth separating two things that post #20 runs together.

The phase 2 obesity paper reported dose-dependent weight reduction of a magnitude that attracted attention. It also reported dose-dependent heart-rate increases. The heart-rate signal is the reason phase 3 exists rather than something assumed negligible based on phase 2.

0 likes 16mo
SK
s.kuuselaTL2 Moderator18 Mar 2025#25
id.almeida, post #21: Mass and identity: a report on retatrutide should state the mass detected by LC-MS, not assume a theoretical mass. The theoretical mass is not published in peer-reviewed literature for retatrutide at present. Go to post

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

2 likes in reply to #21 16mo
TY
two_year_lineTL3Regular18 Mar 2025#26

Coming back to post #24, because the follow-up matters more than the original answer.

TRIUMPH is phase 3 and it is ongoing. No phase 3 results exist. Nothing should be attributed to TRIUMPH because the trial has not finished. When it does, this page will update.

9 likes 16mo
JI
j.iyerTL2 Moderator19 Mar 2025#27

post #26 answers the question as asked. The question underneath it is different.

Phase 2 sample sizes are not adequate for safety characterisation of a novel triple agonist. Phase 3 is where that question gets answered. Using phase 2 results to make claims about safety profile is using the trial for a purpose it was not designed for.

29 likes 16mo
B
batchlogTL3Regular19 Mar 2025#28

Retatrutide is investigational. Anything obtained outside a trial is by definition research-use-only material with no human-use authorisation. This site will state that plainly rather than winking at it.

0 likes 16mo
VN
v.nascimentoTL219 Mar 2025#29
LW
l.wikstromTL2 Moderator20 Mar 2025#30

I read post #28 twice before replying, because I had assumed the opposite.

Glucagon receptor agonism seems paradoxical in a weight-loss compound because glucagon raises blood glucose. The paradox resolves because glucagon agonism also increases energy expenditure and promotes hepatic fat oxidation, and the incretin components offset the glycaemic effect. In diabetes trials, HbA1c improved rather than worsened.

1 like 16mo