Emerging & experimental peptides
A reading directory for peptides at the frontier — from Phase 3 candidates likely to reach the market in the next two to three years to preclinical biology and theoretical mechanisms still years from clinical reality. Each entry is explicitly stage-marked so readers know what they're looking at.
Investigational compounds — read carefully
This section covers peptides at the frontier of research. Most entries are preclinical, in early or mid-stage clinical trials, or theoretical. Evidence levels are explicitly marked on every entry.
Nothing on these pages constitutes medical advice, dosing recommendations, or instructions for use. Many of these compounds are not commercially available; some are not legal for human use. Decisions about treatment require a qualified clinician.
How to use this section
Each entry follows the same structure: short description, current research status (specific trials and milestones), mechanistic rationale, available evidence with PubMed citations, why it's interesting, limitations and risks, and where relevant, community discussion notes. The status chip on each card and at the top of each entry tells you at a glance how clinically advanced the compound is.
For peptides already in mainstream clinical use, see the main peptide index. For practical questions about combinations, the Stacks section is goal-organized. For balanced reads on specific claims, the Honest Reads section is the place.
Late-stage candidates · 6 entries
Compounds in Phase 3 trials or with regulatory approval in some jurisdictions. The closest entries to becoming clinical reality.
Bimagrumab
Anti-ActRIIB monoclonal antibody being tested with semaglutide for muscle preservation during weight loss.
The most-watched non-incretin candidate in the obesity space. Designed to preserve muscle while semaglutide drives fat loss.
Read entryApitegromab
Selective anti-latent-myostatin antibody — a more precise approach to myostatin inhibition.
Scholar Rock's selective approach: bind myostatin only in its latent (inactive) state, blocking its activation rather than the mature ligand. Phase 3 in spinal muscular atrophy with positive results.
Read entryEfruxifermin
FGF21 analog with the most advanced clinical program in the MASH (formerly NASH) liver-disease space.
Akero Therapeutics' Fc-fusion FGF21 analog. Phase 2b SYMMETRY data showed reductions in liver fibrosis at 96 weeks; Phase 3 program is underway.
Read entryPegozafermin
Pegylated FGF21 analog with the second major MASH program in late-stage development.
89bio's pegylated FGF21 analog. Together with efruxifermin, the two define the FGF21-class race in MASH.
Read entryPetrelintide
Long-acting amylin analog. Roche–Zealand partnership in 2025 brought it into front-line obesity competition.
Zealand Pharma's long-acting amylin analog designed for once-weekly dosing. The leading mono-amylin candidate — distinct from cagrilintide, which is paired with semaglutide.
Read entryInsulin icodec
Once-weekly basal insulin — the biggest practical innovation in insulin since long-acting analogs reached the market.
Novo Nordisk's once-weekly insulin. Approved in the EU in 2024; FDA issued a complete response letter in 2024 requesting additional data. The first weekly insulin to reach the market in any major jurisdiction.
Read entryMid-stage emerging · 12 entries
Phase 1–2 candidates with promising early data. The picture is forming but not complete.
Trevogrumab
Regeneron's anti-myostatin monoclonal antibody, currently being studied with semaglutide for muscle preservation.
Regeneron's targeted anti-myostatin antibody pursuing the same muscle-preservation hypothesis as bimagrumab — but with selectivity for myostatin specifically rather than the shared ActRIIB receptor.
Read entryHRS9531
Hengrui Pharma's dual GIP/GLP-1 agonist — part of China's increasingly competitive incretin program.
A Chinese-developed dual incretin agonist with Phase 2 weight-loss data in the same range as tirzepatide. Part of a wave of Chinese metabolic-disease pharmacology entering global discussion.
Read entryPYY 3-36 long-acting analogs
Engineered PYY analogs targeting the appetite-regulation pathway alongside GLP-1.
Novo Nordisk and others are developing long-acting PYY 3-36 analogs that hit a different limb of the appetite-regulation system than GLP-1. Combination with GLP-1 agents is one of the active research questions.
Read entryGDF15 mimetics
Targeting the cachexia / nausea / appetite pathway from a different angle than GLP-1.
GDF15 is the body's own appetite-suppression and stress-response cytokine. Engineered mimetics could provide GLP-1-like effects through an entirely different receptor system.
Read entrySotatercept
An instructive case study — originally developed for muscle preservation, eventually FDA-approved 2024 for pulmonary arterial hypertension.
An activin-trap molecule whose path from anti-cachexia origin to PAH approval is one of the most informative case studies in the muscle-preservation pharmacology space.
Read entryGlepaglutide
Long-acting GLP-2 analog being developed by Zealand Pharma for short bowel syndrome.
An emerging GLP-2 candidate positioned to extend or compete with teduglutide. Once-weekly subcutaneous dosing rather than the daily injections current GLP-2 therapy requires.
Read entryACE-031
Soluble ActRIIB-Fc decoy receptor — Acceleron's myostatin-pathway program halted in DMD over vascular safety signals.
An engineered fusion of activin receptor type IIB extracellular domain with an antibody Fc region designed to act as a circulating decoy that sponges myostatin and related ligands. Phase 2 trials in Duchenne muscular dystrophy were stopped over nosebleed and gum-bleeding signals.
Read entryStamulumab
Wyeth's first-generation anti-myostatin monoclonal antibody — discontinued in 2008 after Phase 1/2 in muscular dystrophies.
The original anti-myostatin antibody program. Stamulumab established that direct myostatin neutralization was tolerable but did not produce meaningful functional benefits in adult muscular dystrophy patients in early trials.
Read entryDomagrozumab
Pfizer's anti-myostatin monoclonal antibody — Phase 2 in DMD discontinued in 2018 after the trial missed its primary endpoint.
A second-generation anti-myostatin antibody from Pfizer, structurally distinct from stamulumab and tested in pediatric Duchenne muscular dystrophy. Discontinued in 2018 after Phase 2 readouts did not show benefit on the four-stair-climb endpoint.
Read entryCotadutide
AstraZeneca's GLP-1 / glucagon dual agonist — discontinued in 2023 after Phase 2 in NASH and chronic kidney disease did not deliver compelling benefit-risk profile.
An early dual GLP-1/glucagon agonist that helped establish the therapeutic concept later carried forward by survodutide, mazdutide, and pemvidutide. The clinical program ultimately ended; the mechanistic lessons live on.
Read entryEfinopegdutide
Hanmi / Merck's once-weekly GLP-1 / glucagon dual agonist — Phase 2b NASH data favorable vs. semaglutide on hepatic-fat endpoints.
Originally developed by Hanmi Pharmaceutical (Korea) and licensed to Janssen, then Merck. Phase 2b NASH trial showed superior hepatic fat reduction vs. semaglutide, supporting continued NASH and obesity development.
Read entryApraglutide
Long-acting GLP-2 analog in Phase 3 for short bowel syndrome — a once-weekly successor to teduglutide's daily dosing burden.
Vectivbio (acquired by Ironwood Pharmaceuticals) is advancing apraglutide as a once-weekly GLP-2 receptor agonist for short bowel syndrome with intestinal failure — a substantial improvement on teduglutide's daily injection requirement.
Read entryPreclinical & theoretical · 12 entries
Preclinical biology and theoretical mechanisms — the frontier of what's being investigated, with the longest distance to clinical use.
α-Klotho
One of the more established 'anti-aging' molecular targets, with cognitive, kidney, and cardiovascular research interest.
An anti-aging hormone whose declining levels track with multiple age-related pathologies. Animal-model rejuvenation effects have been striking; clinical translation remains preclinical.
Read entryIrisin
The 'exercise hormone' whose existence in humans was contested for years. The story is more interesting than either side has admitted.
A peptide cleaved from the membrane protein FNDC5 and released by exercising skeletal muscle. The 2012 discovery generated enormous attention; the subsequent decade of debate over whether it actually exists in humans is one of the more instructive stories in modern peptide biology.
Read entryApelin / ELABELA
Cardiovascular peptide system with significant heart-failure and longevity research interest.
Two endogenous peptide ligands for the APJ G-protein-coupled receptor, with substantial cardioprotective and metabolic biology. Heart-failure-with-preserved-ejection-fraction is the leading clinical interest area.
Read entryAsprosin
A glucogenic appetite-stimulating hormone whose antagonism has been proposed as an anti-obesity therapeutic strategy.
Identified in 2016 as a fasting-induced hormone that stimulates appetite and hepatic glucose production. Asprosin antagonism is being explored as a novel anti-obesity strategy.
Read entryKisspeptin (KP-54)
Endogenous neuroendocrine peptide regulating reproductive hormone release — emerging as a candidate for fertility, sexual response, and mood applications.
A regulator at the top of the reproductive endocrine axis. Imperial College London's Dhillo group has driven much of the early-phase human work, with applications spanning fertility, sexual function, and emotional response.
Read entrySpexin
An endogenous feeding-regulator peptide identified in 2007 — a younger entrant in the appetite-regulation peptide landscape.
A 14-amino-acid peptide acting on galanin receptors in appetite and metabolic regulation circuits. Circulating levels are reduced in obesity, suggesting a potential therapeutic axis through restoration or analog development.
Read entryYK-11
A steroidal myostatin-pathway compound widely sold as a SARM with claimed follistatin-induction effects — minimal clinical research base.
A synthetic steroidal compound originally described in 2011 that has become widely sold in performance-enhancement markets under SARM branding. Marketed claims center on follistatin induction and partial androgen-receptor activity, but the human research base is essentially absent.
Read entryMIF-1
A short synthetic peptide claimed to act as a myostatin antagonist — minimal published clinical or preclinical research validation.
MIF-1 is a tetrapeptide (Tyr-Pro-Leu-Gly-NH2) marketed in grey-market peptide channels as a myostatin inhibitor. The historical literature on the Tyr-Pro-Leu-Gly sequence concerns dopamine and prolactin modulation, not myostatin biology — the myostatin-inhibitor branding is essentially marketing.
Read entryMIF-2
Companion compound to MIF-1 in grey-market myostatin-inhibitor branding — same minimal research base, same naming overlap with older unrelated literature.
MIF-2 is a short peptide marketed alongside MIF-1 in performance-enhancement channels under myostatin-inhibitor branding. Like MIF-1, the contemporary marketing claims substantially outrun the underlying published myostatin-biology research base.
Read entryGDF11
An endogenous TGF-β-superfamily protein at the center of the contested 'young blood' rejuvenation literature — biology real, therapeutic-rejuvenation claims contested.
GDF11 entered the public conversation through high-profile heterochronic parabiosis studies suggesting it as a circulating 'youth factor.' Subsequent replication efforts have been mixed and the rejuvenation framing is widely contested. The underlying biology — TGF-β family signaling through ActRIIB — remains real and relevant.
Read entryAdropin
An endogenous peptide hormone with apparent metabolic-regulatory effects — early academic biology with no advanced clinical program yet.
A 76-amino-acid peptide hormone identified in 2008, encoded by the ENHO gene, with effects on glucose and lipid metabolism, endothelial function, and energy homeostasis. Circulating adropin is reduced in obesity and metabolic syndrome, suggesting a potential therapeutic axis through restoration or analog development.
Read entryAdipotide
A pro-apoptotic peptidomimetic targeting white adipose tissue vasculature — striking rodent obesity reversal data, no clinical development pathway.
Originally developed at MD Anderson, adipotide is a peptidomimetic designed to selectively destroy the vasculature supplying white adipose tissue, producing dramatic obesity reversal in rodent and primate models. Clinical development has not advanced; the renal-toxicity profile is the principal obstacle.
Read entryWhat we update
This section moves faster than the rest of the site. We revise entries when major trials publish, when regulatory milestones happen, and when our reading of the evidence shifts. Last revised: April 2026.