Nausea profile of amylin analogues compared with GLP-1 agonists

Nausea profile of amylin analogues compared with GLP-1 agonists Writing it up because I had to work it out twice and would rather nobody else did.

Session topic: SURPASS-4 (Lancet, 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.

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

What is genuinely unknown about long-term amylin agonism: real-world response rates, whether effect is durable with continued use, whether satiety adaptation occurs over months or years, safety profile in populations not enrolled in the trials.

Is synergy the right word for the combination data? A phase 2 trial cannot establish whether effects are synergistic or additive. Synergy is a mechanistic claim that requires a designed experiment to support it. The combination works, but the mechanism is unsettled.

Cagrilintide molecular characteristics: it is a synthetic amylin analogue, substituted to prevent the amyloidogenicity of human amylin. The sequence is short and analytically straightforward to confirm by LC-MS.

Worth separating two things that the opening post runs together.

Reading the phase 2 paper: it establishes tolerability and efficacy in a selected population on a defined dose escalation. It does not establish the lowest effective dose or the durability over years.

post #5 is right about the mechanism and I think understates the practical bit.

Historical amylin analogues: pramlintide was the only long-acting amylin analogue licensed for some time and its poor adherence was a known limitation. A weekly formulation addresses that practical barrier.

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.

For anyone arriving from searches on "amylin agonist": this subcategory discusses published clinical evidence and what it does and does not establish. It does not endorse or recommend the compounds discussed.

On post #5 — agreed on the reasoning, with one qualification.

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

post #9 answers the question as asked. The question underneath it is different.

Amylin signalling is distinct from GLP-1 signalling. Amylin slows gastric emptying and promotes satiety through a different receptor and different neural pathways. The hypothesis behind combination is two complementary satiety mechanisms with one injection.

post #10 is right about the mechanism and I think understates the practical bit.

Gastric emptying: both amylin and GLP-1 slow it, through partly overlapping but distinct mechanisms. Whether the slowing at a higher magnitude produces disproportionate nausea or is tolerable is a question phase 3 exists to answer.

Worth separating two things that post #8 runs together.

The dosing interval: cagrilintide's half-life is roughly 7 to 8 days, suitable for weekly dosing. The pharmacokinetics are the reason the dosing schedule makes sense.

Cagrilintide alone is discussed less than in combination because the published data is almost entirely from combination trials. The phase 2 combination data was consistent with more effect than either component alone, but phase 2 cannot establish whether that is synergy or simply additivity.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.