PTT-A is an investigational, long-acting peptide from Pep2Tango Therapeutics designed as a quadruple receptor agonist (a tetra-agonist): one molecule built to activate the GLP-1, GIP, amylin and calcitonin receptors. Its developer describes it as joining the incretin activity of a GLP-1/GIP dual agonist and the amylin/calcitonin activity of an agonist like cagrilintide in a single peptide. The research published so far is preclinical: cell assays and rodent studies presented as conference abstracts.

How Does PTT-A Work?

PTT-A combines four receptor activities in one molecule. All four are class B G protein-coupled receptors, and laboratories usually measure their activation in cell assays that read out cyclic AMP (cAMP).

1. GLP-1 receptor

GLP-1 receptors take part in glucose-dependent insulin secretion and gastrointestinal signaling. They are the shared core of almost every incretin multi-agonist.

2. GIP receptor

GIP receptors also take part in glucose-dependent insulin signaling. Research on combined GLP-1 and GIP activation led to dual agonists like tirzepatide.

3. Amylin receptors

Amylin is a peptide hormone released alongside insulin by pancreatic beta cells. Amylin receptor signaling is studied for its role in gastric emptying and food-intake signaling. Amylin analogs such as cagrilintide and eloralintide are studied on their own and in combinations.

4. Calcitonin receptor

The calcitonin receptor takes part in calcium regulation. It also forms the core of amylin receptors: when the calcitonin receptor pairs with a receptor activity-modifying protein (RAMP1, 2 or 3), the complex responds to amylin.

Scientific distinction: because amylin receptors are built on the calcitonin receptor, PTT-A’s four targets are not four fully independent pathways. Its amylin and calcitonin activities overlap at the receptor level, the same pairing seen in dual amylin and calcitonin receptor agonists (DACRAs) like cagrilintide.

PTT-A vs Retatrutide: What’s the Difference?

Both are multi-receptor agonists, but their receptor profiles differ.

Receptor target	PTT-A	Retatrutide
GLP-1	Yes	Yes
GIP	Yes	Yes
Glucagon	Not a reported target	Yes
Amylin	Yes	Not a reported target
Calcitonin	Yes	Not a reported target
Class	Quadruple (tetra-) agonist	Triple agonist
Developer	Pep2Tango Therapeutics	Eli Lilly and Company
Stage	Preclinical (published data)	Phase 3 (TRIUMPH program)

PTT-A is not retatrutide with a fourth target added. It is a different molecule built on a different strategy, and the two are not chemically equivalent or interchangeable.

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