Coming back to: Amylin analogue mechanism: satiety signalling separate from GLP-1

On the subject in the title: Amylin analogue mechanism: satiety signalling separate from GLP-1 Working notes rather than a conclusion.

I have seen SELECT (N Engl J Med, 2023) cited in support of a claim I do not think it supports, twice this month, so I would like to work through what it actually shows.

My reading is that the trial is sound for its own question and is being stretched to answer a different one. I might be wrong about that, which is why this is a topic rather than a correction.

What I would like from this discussion: someone who disagrees with me to say why, with the section of the paper they are relying on.

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

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.

Worth separating two things that post #2 runs together.

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.

Picking up post #2: that is the part I would want checked first.

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.

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.

On post #4 — agreed on the reasoning, with one qualification.

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.

The CagriSema phase 2 paper: a fixed combination of the two components in one weekly injection. The trade-off of a fixed combination is that you cannot titrate the components independently and you cannot attribute effect to one component from a combination trial.

I read post #8 twice before replying, because I had assumed the opposite.

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.

Nausea profile of amylin analogues: the historical agent pramlintide required multiple daily doses and had a difficult tolerability profile. A weekly formulation is a substantially different proposition and data from that is more relevant than data from pramlintide.

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.

I read post #11 twice before replying, because I had assumed the opposite.

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.

This follows post #11 rather than contradicting it.

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.