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Author: kodiac

Valproic Acid (Topical Hair)

Our opinion on this compoundSingle-lab provenance

43/100

Single-group Korean data on a smart HDAC-Wnt mechanism; real signal but starved for replication

Look, valproic acid is one of the most prescribed drugs on the planet for epilepsy and mood disorders, so calling it novel would be embarrassing. What’s actually interesting here is the research hypothesis layered on top of a well-understood molecule: HDAC inhibition increases histone acetylation at Wnt target gene promoters, and the Wnt/beta-catenin pathway is genuinely central to hair follicle anagen induction. That mechanistic logic is sound. The canonical Wnt pathway has been a serious target in hair biology since at least the early 2000s, and if you can reliably activate it topically without the systemic hit, the pharmacological argument writes itself.

The evidence base is where things get honest. Essentially all of the published clinical work comes out of a single Yonsei University group in Korea, the same investigators who developed the PTD-DBM peptide (KDC-MN-1347). Their 8.3 percent (roughly 50 mg/mL) topical solution reported hair count and density improvements over 24 weeks in androgenetic alopecia subjects, which is real human signal. But small N, single-center, single-group data is exactly the kind of finding that looks strong until it doesnt replicate. We’ve seen this pattern repeatedly in the hair biology space. The combination work with PTD-DBM is genuinely interesting as a synergistic Wnt-activating stack, and the ex vivo data is mechanistically coherent, but it deepens the single-consortium dependency rather than resolving it.

What we like about this compound: the mechanism angle is not me-too. HDAC inhibition as a route to Wnt activation is differentiated from the minoxidil (vasodilatory) and finasteride (5-alpha reductase) approaches that dominate clinical practice. If topical HDAC inhibition can drive meaningful anagen extension without systemic exposure, thats a genuinely different tool. Valproic acid also has decades of HDAC inhibitor pharmacology behind it, so the target biology is well-characterized, and you’re not flying blind on the molecular action. The systemic safety concerns (hepatotoxicity, teratogenicity with Depakote) are mostly an academic concern for topical research use given the limited transdermal absorption and extensive first-pass metabolism, though the pregnancy contraindication is worth flagging in any protocol design.

What we don’t like: the evidence is thin and highly concentrated in one group. There’s no multi-lab replication, no large-N RCT, and no mechanistic confirmation from independent investigators. The differentiation from established AGA therapies is mechanistically real but practically unproven at scale. For an investigator considering this as a bench target, the Yonsei data gives you a meaningful starting point but the replication risk is significant. Honestly, this is one of the more intriguing single-lab stories in dermatology research right now, but intriguing single-lab story is exactly what it is until someone else runs the experiment.

Novelty

40

Mechanism promise

55

In-category differentiation

45

Evidence quality

30

Translational signal

38

Research bench value

45

Rationale Valproic acid itself is a decades-old antiepileptic; its score here rests on a mechanistically coherent HDAC-to-Wnt hypothesis and small-N RCT human data from Yonsei University, but essentially all published clinical evidence is from one consortium, making independent replication the critical unknown that limits the overall.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

HDAC inhibitor and topical hair regrowth research compound

The histone deacetylase inhibitor valproic acid in topical formulation, studied as a Wnt-pathway-activating agent for androgenetic alopecia in academic dermatology research.

Abstract

Valproic acid (2-propylpentanoic acid; CAS 99-66-1; molecular formula C8H16O2; molecular weight 144.21) is a branched short-chain fatty acid in widespread clinical use as the antiepileptic and mood-stabilizer Depakote (sodium valproate; KDC-MN; sodium-valproate). The systemic monograph for sodium valproate is published separately. The topical use of valproic acid for hair regrowth is the subject of this monograph and represents a research-application of the same chemical entity. The pharmacological argument for topical valproic acid in hair is derived from the histone deacetylase inhibitor activity of the compound and the dependence of canonical Wnt/beta-catenin signaling on histone acetylation at Wnt target gene promoters; HDAC inhibition increases Wnt target gene expression and promotes anagen-phase hair follicle activity. Korean academic groups (notably Yonsei University, with the same investigator group developing the PTD-DBM peptide; KDC-MN-1347) have published case-series and small randomized trial data on topical 8.3 percent valproic acid solution for androgenetic alopecia, reporting hair count and density improvements over 24 weeks at frequencies suggestive of meaningful efficacy. The combination with topical PTD-DBM has been studied as a synergistic Wnt-activating regimen with reported additive efficacy in ex vivo and in vivo models. Topical valproic acid is not FDA-approved for any indication; it is compounded by specialty pharmacies for off-label hair use. The systemic safety considerations of valproic acid (hepatotoxicity, teratogenicity, neural tube defects) are substantially mitigated in topical use owing to the extensive first-pass metabolism if absorbed and the limited cumulative dose, but pregnancy contraindication should be observed. Reconstitution into a topical solution typically uses ethanol, propylene glycol, and water; the 8.3 percent (50 mg/mL) solution is the most-studied concentration.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

May 10, 2026
Larazotide

Our opinion on this compoundNiche research probe

55/100

First-in-class zonulin antagonist with a clean mechanism and unique bench utility, hurt badly by a 2022 Phase 3 miss

Look, larazotide occupies a genuinely unusual position in the research peptide landscape. Its mechanism is specific in a way that most gut-targeted peptides arent: it competes at the zonulin receptor and blocks ZOT/zonulin-driven tight junction disassembly without touching baseline junctional integrity. That selectivity is not a marketing angle, it comes from Alessio Fasanos group at Maryland building off the structural homology between the Vibrio cholerae ZOT toxin and pre-haptoglobin 2, the endogenous zonulin ligand. No other compound available to investigators does this specific thing at the receptor level.

The problem is the 2022 CeDLara Phase 3 readout. 9 Meters Biopharma ran a well-powered trial targeting symptomatic celiac patients on a gluten-free diet who still experience residual symptoms, presumably from gluten cross-contamination driving tight junction disruption. The primary endpoint, a celiac disease patient-reported outcome score, didnt move. That is a real failure and we’re not going to dress it up. Secondary analyses showed some biological signal, and the compound clearly reached its target (gut-luminal exposure is the whole point of an unabsorbed oral peptide), but the field is right to read this as a setback for the celiac indication specifically.

What keeps larazotide interesting as a research compound is that the mechanism failure hypothesis hasnt been established. The Phase 3 miss is more plausibly a trial design and endpoint selection problem than a biology problem. The leaky-gut phenotype in symptomatic celiac on GFD is heterogeneous, and PRO endpoints in that population are notoriously noisy. The tight junction dysregulation story in IBD, multiple sclerosis, and type 1 diabetes is mechanistically distinct from celiac and remains under active investigation. Larazotide is the only tool that lets you ask what happens when you specifically block the zonulin arm of tight junction opening in those contexts, in vivo, without the off-target pharmacology that comes with broader TJ modulators.

For a bench program focused on intestinal barrier function, this compound has real probe value. The zero systemic absorption profile is actually an asset: you can dose luminally and confine your intervention to the gut without worrying about peripheral effects, which makes attribution cleaner. We think the strongest use cases right now are gut-permeability models in autoimmune disease contexts where the zonulin axis has a plausible mechanistic role, not celiac disease per se. Evidence quality is solid for a research peptide, multiple Phase 2 trials with real data, but the Phase 3 failure and the narrow indication space keep the overall compelling-target score in the mid-50s. Honest assessment: this is a niche tool, not a headline compound, but for the right program its the only tool that fits.

Novelty

48

Mechanism promise

58

In-category differentiation

68

Evidence quality

55

Translational signal

35

Research bench value

65

Rationale Larazotide earns above-average differentiation because it remains the only specific pharmacological tool for probing the zonulin/tight junction axis in vivo and in ex vivo intestinal models; the Phase 3 failure in celiac disease (CeDLara, 2022) drags translational signal sharply down but does not disprove the mechanism, which is intact and still relevant in IBD, MS, and barrier-dysfunction research.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

Zonulin antagonist octapeptide and tight junction modulator

An eight-residue zonulin receptor antagonist developed by Innovate Biopharmaceuticals (now 9 Meters Biopharma) as the first specific gut tight junction modulator advanced to Phase 3 in celiac disease.

Abstract

Larazotide acetate (Gly-Gly-Val-Leu-Val-Gln-Pro-Gly; CAS 258818-34-7; molecular weight 754.86 free peptide) is an eight-residue synthetic peptide developed at the University of Maryland by Alessio Fasano and colleagues as a competitive antagonist at the zonulin receptor. Zonulin (also designated pre-haptoglobin 2) is the human ortholog of the Vibrio cholerae zonula occludens toxin (ZOT) and is the only known endogenous regulator of intestinal epithelial tight junction permeability; activation of the zonulin pathway in response to gluten exposure or other triggers produces transient opening of intestinal tight junctions and translocation of luminal antigens into the lamina propria, contributing to celiac disease pathogenesis and a broader leaky-gut phenotype implicated in autoimmune and inflammatory conditions. Larazotide binds the zonulin receptor and blocks ZOT/zonulin-induced tight junction disassembly without directly affecting baseline tight junction integrity. The compound was advanced through Phase 1 and Phase 2 trials in celiac disease and entered Phase 3 (CeDLara) for the residual gluten-cross-contamination phenotype in patients on a gluten-free diet who continue to experience symptoms. The Phase 3 readout in 2022 did not meet the primary endpoint of celiac disease patient-reported outcome, and 9 Meters Biopharma announced discontinuation of the program. Despite the clinical setback in celiac disease, larazotide remains a pharmacologically distinct research tool for tight junction modulation in inflammatory bowel disease, multiple sclerosis, and other indications where intestinal barrier dysfunction is implicated. Oral bioavailability is essentially zero (the peptide acts in the gut lumen and is not absorbed); the route of administration is per oral as a sustained-release formulation. Adverse events in clinical trials were mild and dominated by gastrointestinal effects.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

May 10, 2026
NA-Selank

Our opinion on this compoundSingle-lab provenance

37/100

PK-optimized Selank derivative with rational chemistry but single-lab evidence base and narrow bench utility

Here’s the thing about NA-Selank: it’s a well-conceived pharmacokinetic improvement on an already-interesting compound that happens to live almost entirely inside a single Russian research ecosystem. Selank itself, the parent heptapeptide, is registered in Russia as an intranasal anxiolytic and has a legitimate anxiolysis-without-sedation profile backed by tuftsin-receptor biology, GABAergic modulation, and BDNF transcriptional upregulation. The N-acetyl modification at the threonine N-terminus blocks the primary aminopeptidase cleavage site and extends plasma half-life roughly fivefold. The Amidate variant adds C-terminal amidation to block carboxypeptidase attack at the proline tail. Both modifications are rational, well-precedented chemistry. The resulting molecules are better candidates for parenteral administration with meaningful CNS exposure duration than the parent intranasal compound.

We like the underlying logic. The tuftsin-receptor angle is genuinely underexplored in Western literature. Tuftsin is an endogenous tetrapeptide with immunomodulatory activity on monocytes and natural killer cells, and the Selank backbone preserves that biology. With extended plasma exposure from the N-acetyl modification, the immune-modulatory component may operate differently than it does during the brief intranasal pulse of the parent compound. That’s an actually interesting research question. The BDNF upregulation claims, meanwhile, slot into a crowded field where every third peptide is said to boost neurotrophins, so we weight that more cautiously.

The evidence situation is the central problem. Published characterization is dominated by the Institute of Molecular Genetics RAS group, principally in Russian-language journals, with very limited independent replication. That puts NA-Selank in similar epistemic territory to Epitalon or classic Khavinson peptides: real preclinical work exists, but the absence of external replication means the error bars are wide. There are no human trials on the NA variants specifically. The parent Selank’s Russian registration provides some translational signal, but extrapolating from approved-intranasal to research-parenteral is a meaningful step with its own unknowns about exposure kinetics and CNS distribution in humans.

What NA-Selank does well as a research tool is give investigators a parenteral-compatible version of the Selank backbone for studying CNS anxiolytic peptide pharmacology, tuftsin-receptor biology, and the differential immunomodulatory profile under sustained versus pulsed exposure. That’s a legitimate but narrow use case. If your program isnt already anchored in peptide anxiolytics or tuftsin biology, theres little reason to prioritize this over compounds with better-replicated preclinical packages. For investigators already in that space, the extended-PK variants are worth having in the toolkit, but theyre supplementary tools rather than foundational ones. A score of 37 reflects exactly that: interesting enough to catalog, not compelling enough to center a program on.

Novelty

45

Mechanism promise

42

In-category differentiation

38

Evidence quality

25

Translational signal

28

Research bench value

38

Rationale NA-Selank’s N-acetylation and amidation modifications are pharmacokinetically sound and produce a legitimate parenteral research tool, but the evidence base is dominated by a single Russian research consortium with minimal independent replication, and the compound’s utility is narrow outside tuftsin or peptide anxiolytic research programs.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

N-acetylated Selank derivatives with extended pharmacokinetics

N-terminal-acetylated and amidated variants of the heptapeptide anxiolytic Selank, designed to extend plasma and central nervous system exposure beyond the parent peptide.

Abstract

NA-Selank (N-acetyl-Thr-Lys-Pro-Arg-Pro-Gly-Pro) and NA-Selank Amidate (the same N-acetylated heptapeptide with C-terminal amidation, Pro-NH2) are N-terminal-modified derivatives of Selank, the seven-residue peptide anxiolytic developed at the Russian Academy of Sciences as an analog of the endogenous tetrapeptide tuftsin (Thr-Lys-Pro-Arg). The parent Selank is registered as a medicine in the Russian Federation as an intranasal anxiolytic at 0.15 percent solution; the principal pharmacological signature is anxiolysis without sedation, modest pro-cognitive activity, and immunomodulation through tuftsin-receptor binding on monocytes and natural killer cells. Selank itself has a short plasma half-life of minutes and is administered intranasally to leverage direct olfactory and trigeminal transport to the central nervous system; the N-acetyl modification at the threonine N-terminus blocks the principal aminopeptidase cleavage site and extends plasma half-life by approximately 5-fold, while the C-terminal amidation in the Amidate variant similarly blocks carboxypeptidase cleavage at the proline C-terminus. The combined modifications produce a heptapeptide with substantially extended exposure suitable for parenteral administration with central nervous system effect. Mechanism includes BDNF transcriptional upregulation, GABAergic and serotonergic modulation, and tuftsin-receptor immunomodulation. Both NA-Selank and NA-Selank Amidate are research-grade peptides without regulatory approval; published characterization is principally in Russian-language journals and is dominated by the originating Institute of Molecular Genetics RAS research group. Investigators should treat the extended-PK variants as research tools for studying parenteral Selank pharmacology and should consider that the immune-modulatory profile may be more pronounced with extended exposure than with the brief intranasal pulse achieved by the parent.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

May 10, 2026
Macimorelin

Our opinion on this compoundEstablished, active research

52/100

Approved oral GH secretagogue with strong diagnostic evidence but narrow research frontier appeal

Look, macimorelin has a genuinely impressive regulatory pedigree. It’s the first and only oral agent approved by both the FDA (December 2017) and EMA (January 2019) specifically for adult growth hormone deficiency diagnosis, displacing the insulin tolerance test as the clinical reference standard in many centers. That’s a real achievement in drug development. The problem, from a research standpoint, is that it basically solved a diagnostic problem and then stopped being interesting as a frontier target.

The mechanism is solid but not exciting. GHS-R1a agonism is mature pharmacology at this point. Macimorelin’s main trick is peptidomimetic design: Fehrentz and Martinez at Montpellier took the hexarelin scaffold and used alpha-aminoisobutyric acid capping plus two indole-containing side chains to create something orally bioavailable and protease-resistant. Thats genuinely good medicinal chemistry. But it’s not a novel mechanism. The receptor is well-characterized, the downstream GH pulse is predictable, and the diagnostic sampling window at 45 and 90 minutes post-dose is clean precisely because there are no pharmacological surprises.

Where macimorelin earns its score is evidence quality and translational signal within the diagnostic indication. The Garcia 2013 phase 2 and Garcia 2018 phase 3 pivotal trial showed sensitivity and specificity competitive with the ITT without the hypoglycemia risk. Yuen et al. (2021) refined diagnostic cutoffs and validated the approach further. That’s multi-center, well-replicated, regulatory-grade data. Herodes et al. (2023) ran a cancer cachexia pilot that generated some early signal, and there’s preclinical work in seizure models and neuroprotection worth watching. None of those secondary programs are anywhere close to the clinical rigor of the approved diagnostic evidence base.

Differentiation is genuinely high inside the diagnostic niche: no competing compound holds this regulatory status for AGHD. But bench investigators using GHS-R1a agonists as tools usually reach for ipamorelin, ghrelin itself, or MK-677 first, depending on the question. Macimorelin’s oral bioavailability is practically convenient, but the receptor pharmacology doesnt unlock biology that injection-route secretagogues can’t reach. It’s a cleaner clinical tool than a uniquely powerful research probe.

We think macimorelin belongs in any program centered on AGHD diagnostics, pediatric GH axis assessment, or ITT-comparison methodology. The cachexia follow-on data is worth a second look, and the neuroprotective preclinical angle is real, if thin. Outside those lanes, it’s a solved problem. A serious bench scientist interested in GHS-R1a biology has better-explored tools. The score reflects a compound that did exactly what it set out to do and is now living in a well-lit but narrow corridor of the literature.

Novelty

35

Mechanism promise

40

In-category differentiation

62

Evidence quality

68

Translational signal

65

Research bench value

50

Rationale Macimorelin earns solid evidence and translational scores because it is a genuinely approved diagnostic drug with clean phase 3 data, but GHS-R1a agonism is mature pharmacology and the compound’s differentiation is tightly confined to the AGHD diagnostic niche; outside that lane it offers no special probe value over ipamorelin or ghrelin itself, which keeps novelty and mechanism scores low and pulls the overall into the low fifties.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

Synthetic peptidomimetic growth hormone secretagogue receptor type 1a (GHS-R1a) agonist

An orally active peptidomimetic ghrelin receptor agonist developed at the University of Montpellier and advanced by Aeterna Zentaris as the first and only approved oral diagnostic test for adult growth hormone deficiency, distinguished from other growth hormone secretagogues by its validated diagnostic application and favorable safety profile relative to the insulin tolerance test.

Abstract

Macimorelin (JMV-1843, EP-1572, AEZS-130), a synthetic peptidomimetic agonist of the growth hormone secretagogue receptor type 1a (GHS-R1a, the ghrelin receptor), is the first and only orally administered diagnostic agent approved by the United States Food and Drug Administration (December 2017) and the European Medicines Agency (January 2019) for the evaluation of adult growth hormone deficiency (AGHD). The compound was invented and first synthesized at the University of Montpellier and the Centre National de la Recherche Scientifique (CNRS) in France by Fehrentz, Martinez, Guerlavais, and colleagues as part of a structure-activity program seeking orally bioavailable growth hormone secretagogues derived from the hexarelin scaffold, and was subsequently licensed to Aeterna Zentaris for clinical development and marketed under the trade names Macrilen (United States, Novo Nordisk) and Ghryvelin (European Union, Consilient Health and subsequently Pharmanovia) [1, 2]. Structurally, macimorelin is a modified tripeptide containing two indole (tryptophan-derived) moieties linked through a central peptidomimetic backbone with a terminal formamide group and an N-terminal alpha-aminoisobutyric acid cap, conferring oral bioavailability and resistance to proteolytic degradation that distinguish it from the earlier peptide-based growth hormone secretagogues such as GHRP-6 and hexarelin.

The compound binds the GHS-R1a receptor on pituitary somatotroph cells with an IC50 of 22.9 nanomolar in human pituitary tissue and activates the Gq/11-phospholipase C signaling cascade, stimulating endogenous growth hormone release into the systemic circulation in a manner pharmacologically analogous to the endogenous ligand ghrelin [2, 3]. Following oral administration at the diagnostic dose of 0.5 mg/kg body weight, macimorelin produces a robust and reproducible rise in serum growth hormone concentration that peaks between 30 and 90 minutes post-dose, permitting diagnostic discrimination between growth hormone-sufficient and growth hormone-deficient adults through serial blood sampling over a 90-minute test window. The Phase 3 confirmatory trial (Garcia et al., 2018) in 157 adults demonstrated 87 percent sensitivity and 96 percent specificity at a growth hormone cutoff of 2.8 ng/mL, with 97 percent reproducibility on repeat testing, establishing macimorelin as a clinically validated alternative to the insulin tolerance test with the practical advantages of oral administration, absence of hypoglycemia risk, and a shorter, simpler test protocol [4, 5].

Pharmacokinetics are characterized by rapid oral absorption (median time to peak plasma concentration approximately 0.75 hours), hepatic metabolism predominantly through cytochrome P450 3A4 (CYP3A4) to a partially active O-demethylated metabolite, a terminal elimination half-life of approximately 4.1 hours, approximately 70 percent plasma protein binding, and predominantly fecal excretion [6, 7]. Food substantially reduces both the rate and extent of absorption (Cmax reduction of approximately 55 percent, AUC reduction of approximately 44 to 49 percent with a high-fat meal), mandating overnight fasting before the diagnostic test. The principal drug interaction concern is with strong CYP3A4 inducers (which may reduce macimorelin exposure and produce false-positive diagnostic results) and strong CYP3A4 inhibitors (which may elevate exposure). The compound produces a mean increase in the corrected QT interval of approximately 11 milliseconds at the diagnostic dose, requiring avoidance of concomitant QT-prolonging medications during the test [8].

Adverse events in clinical trials were mild and transient, with dysgeusia (bitter or metallic taste), dizziness, headache, nausea, fatigue, hunger, and diarrhea reported at low frequencies. No serious adverse events attributable to macimorelin were reported in the pivotal trials across more than 1000 administered subjects [5, 8]. The compound is administered as a single diagnostic dose rather than as a chronic therapeutic regimen, and the safety profile reflects this acute exposure context. Beyond the diagnostic indication, macimorelin has been investigated in cancer cachexia (pilot trial demonstrating safety and numerical weight improvement) and in pharmacoresistant epilepsy (preclinical seizure suppression through GHS-R1a-mediated neuroprotection), though the compound is not approved for any therapeutic application [9, 10].

This monograph reviews the chemistry, synthesis, and structural pharmacology of macimorelin; the GHS-R1a receptor mechanism in molecular detail; the comprehensive human pharmacokinetic record; the preclinical and clinical evidence base across diagnostic and investigational applications; reconstitution and handling considerations; stack interactions and drug-drug interaction considerations; the adverse-event and safety signal; and a comparative assessment of five growth hormone secretagogue or diagnostic candidates (insulin tolerance test, glucagon stimulation test, anamorelin, ibutamoren, and GHRH-arginine test) against macimorelin on five competency standards (novelty, effect size, promising potential, side-effect profile, and overall validation).

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

May 10, 2026
Pentadeca Arginate (PDA)

Our opinion on this compoundNiche research probe

28/100

A formulation variant of BPC-157 with no independent pharmacological literature or novel mechanism

Look, here’s the thing about PDA: the peptide is BPC-157. Exactly. Same sequence (Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val), same molecular weight at 1419.55 for the free peptide, same pharmacological targets, same mechanism. What’s different is the counterion (arginate instead of acetate), which vendors argue improves aqueous stability and extends lyophilized shelf life. Thats a real formulation win for labs that want better consistency in their peptide preps. It is not a new compound.

This matters a lot for scoring. PDA has no independent published preclinical record. Zero papers. The entire pharmacological basis for PDA comes from the BPC-157 acetate literature, which itself has a serious problem: it’s almost entirely generated by a single research group (Sikiric, University of Zagreb). We’ve covered this in detail in the BPC-157 monograph. The tendon healing, vascular reorganization, GI mucosal protection signals are real preclinical observations, but independent multi-lab replication is thin, and human evidence is essentially absent. When you’re rating PDA on evidence quality, you’re rating a compound with no publications of its own, built on top of a literature with existing replication issues.

On differentiation, PDA is strictly downstream of BPC-157 acetate, not above it. The only dimension where PDA has an argument is formulation stability, and even that claim is based on vendor literature rather than published comparative stability studies under controlled lab conditions. An investigator choosing between BPC-157 acetate and PDA is making a handling decision, not a scientific one. There is no pharmacological reason to expect different outcomes between the two.

We do give some credit for bench value. If you’re running an active BPC-157 research program, PDA offers a potentially more stable working stock, which has genuine practical value in peptide work where gradual degradation can introduce noise into your data. Thats not nothing. But it doesnt elevate PDA into meaningful independent research territory; the upstream BPC-157 evidence questions don’t go away because the salt counterion changed.

What we don’t like: this is a textbook vendor catalog phenomenon. PDA emerged in 2023-2024 as peptide suppliers differentiated product lines, not from any published scientific advance. The improved stability framing is a marketing angle until head-to-head comparative stability data under real lab conditions actually gets published. Investigators should treat PDA as a formulation option within an existing BPC-157 research program, not as an independent compound warranting its own inquiry. If you’re not already running BPC-157 work, PDA gives you no scientific reason to start.

Novelty

35

Mechanism promise

40

In-category differentiation

18

Evidence quality

15

Translational signal

20

Research bench value

38

Rationale PDA is pharmacologically identical to BPC-157 acetate; its only differentiator is counterion choice for handling stability. With zero independent published data and no mechanism beyond what the Sikiric group established for the parent peptide, PDA scores low across novelty, evidence, and differentiation, landing well below the BPC-157 calibration anchor.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

Arginate salt analog of BPC-157

A research-grade arginate salt formulation of the pentadecapeptide BPC-157 sequence, formulated for improved aqueous stability and shelf life relative to acetate-salt parent.

Abstract

Pentadeca Arginate (PDA; the pentadecapeptide Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val formulated as the arginate salt; the underlying peptide is identical to BPC-157, CAS 137525-51-0; molecular formula C62H98N16O22 free peptide; molecular weight 1419.55 free peptide; the arginate salt adds counterions and is formulated for improved stability) is a research-grade alternative formulation of the BPC-157 pentadecapeptide that has emerged in research-grade peptide vendor catalogs in 2023 to 2024 as a stabilized analog. The pharmacological argument is that the arginate counterion improves aqueous solubility and extends shelf life of the lyophilized solid relative to acetate-salt BPC-157, which is the standard formulation; the underlying peptide sequence and pharmacology are identical, and any differences between PDA and BPC-157 in vivo are attributable to formulation rather than to a different molecule. The published preclinical record on the BPC-157 sequence is summarized in the Kodiac BPC-157 monograph (KDC-MN-002): tendon and ligament healing, vascular reorganization, gastrointestinal mucosal protection, dopaminergic system modulation, broad rodent injury-recovery activity, with the limitation that the literature is dominated by the originating Sikiric group at the University of Zagreb. PDA has no independent published preclinical record beyond the parent BPC-157 work; vendor literature emphasizes formulation stability claims rather than novel pharmacology. Investigators should not assume that PDA differs pharmacologically from BPC-157 acetate; the choice between formulations should be made on stability and handling considerations. Reconstitution and dosing follow BPC-157: bacteriostatic water for injection, refrigerated storage of reconstituted solution, parenteral administration at 250 to 500 mcg per dose. The compound is research-grade and not approved by any regulatory authority for human or veterinary use.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

May 10, 2026
Thymosin alpha 1 (Thymalfasin)

Our opinion on this compoundEstablished, active research

50/100

Decades-old thymic immunomodulator with real approval history but aging novelty and mixed recent trial results

Here’s the thing about Thymosin alpha-1: it’s genuinely approved in 35 jurisdictions, has a real randomized trial database behind it, and sits on a mechanistic foundation that’s more interesting than most thymic peptides. Allan Goldstein’s group at Albert Einstein College of Medicine isolated it from thymus fraction 5 in 1977, SciClone developed it into Zadaxin, and it’s been approved for chronic hepatitis B across most of Asia and Latin America for decades. That history is both its credential and its problem as a research target today.

The mechanism is legitimately multifactorial. Talpha1 signals through TLR9 on plasmacytoid dendritic cells, which biases adaptive response toward Th1 and enhances NK cytotoxicity. On top of that theres a context-dependent effect on regulatory T cell phenotypes that makes it particularly interesting in chronic infection and tumor microenvironment models. That complexity is more intellectually interesting than simple single-cytokine agonism. We like that. What we don’t like is that this biology has been worked over for 40 years now, and the marginal information density from a new Talpha1 preclinical study is genuinely low. The mechanism is understood. The question is whether you can use that understanding to answer something new.

The COVID and sepsis trials are where this compound’s recent research trajectory gets complicated. The CHEETAH trial in Italy ran Talpha1 in critically ill COVID-19 patients and landed essentially neutral on 28-day mortality. Multiple Chinese RCTs showed modest benefit in severe COVID, but those results didn’t replicate cleanly against the Italian or Western trial data. That divergence is scientifically interesting on its own terms, especially because the Treg phenotype heterogeneity across disease contexts probably explains a lot of it. A serious investigator could build a research program around resolving that question. But the overall translational picture is messier than the hepatitis B approval record suggests.

Within its class, Talpha1 is the obvious dominant compound. Thymalin, Thymopentin, Thymulin, and the broader Thymosin Fraction 5 extract all sit clearly below it on evidence quality and regulatory standing. For researchers specifically working on thymic peptide biology, innate/adaptive immune crosstalk in chronic disease, or checkpoint modulation in immunocompromised oncology models, it’s the reference compound. The 1.6 mg subcutaneous twice-weekly schedule is well-characterized from decades of clinical use, which at least makes experimental design tractable in ways that single-lab peptides rarely are.

Honestly, if your lab is working immune restoration biology, tumor microenvironment immunomodulation, or chronic viral infection models, Talpha1 is a legitimate tool with real clinical precedent behind it. It’s not a frontier compound. Its days as a novel research subject are behind it. But for groups where the question is how thymic peptides reshape adaptive immune phenotypes under chronic antigen load or sepsis-induced immunoparalysis, this is still the compound with the deepest evidence base in its class. Score reflects exactly that: real, validated, and aging.

Novelty

28

Mechanism promise

42

In-category differentiation

62

Evidence quality

65

Translational signal

60

Research bench value

50

Rationale Talpha1 earns its moderate score through genuine regulatory approval in 35 jurisdictions and a multifactorial TLR9/Th1/NK mechanism more interesting than most thymic peptides, but novelty is low (1977 isolation, decades of clinical use) and the COVID/sepsis RCT wave produced heterogeneous results that complicate the translational picture. Differentiation within the thymic peptide class is strong; it’s the only member with real RCT depth and regulatory standing, which keeps the score from falling further.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

28-residue immunomodulatory thymic peptide

A 28-amino-acid acetylated peptide originally isolated from thymus tissue, registered as Zadaxin in approximately 35 jurisdictions for chronic hepatitis B and as adjunctive therapy in immunocompromised oncology patients.

Abstract

Thymosin alpha 1 (Talpha1; Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn; thymalfasin; CAS 62304-98-7; molecular formula C129H215N33O55; molecular weight 3108.27) is a 28-residue N-acetylated peptide originally isolated from bovine thymus tissue by Allan Goldstein and colleagues at the Albert Einstein College of Medicine in 1977 as a fraction of the broader thymosin fraction 5 immunomodulator. The synthetic peptide was developed by SciClone Pharmaceuticals as Zadaxin and approved in approximately 35 jurisdictions (including most of Asia, Latin America, and parts of Europe) for chronic hepatitis B, chronic hepatitis C (in combination with interferon and ribavirin), and as adjunctive immune-restorative therapy in immunocompromised oncology patients. The compound is not FDA-approved (Phase 3 trials in hepatitis C did not establish independent efficacy at the threshold required by FDA; the agent is approved on different evidence packages in the jurisdictions where it is marketed). Mechanism is multifactorial immunomodulation: enhancement of T cell maturation through Toll-like receptor 9 signaling on dendritic cells, increased Th1 cytokine production, enhanced natural killer cell cytotoxicity, and a more complex effect on regulatory T cell phenotypes that varies with disease context. Routes of administration are subcutaneous twice weekly at 1.6 mg per dose. The compound is distinct from the broader Thymosin Fraction 5 extract and from other thymosin family peptides (Thymosin beta-4, KDC-MN-003; Thymalin; Thymulin; Thymopentin) in being the principal alpha-class thymic immunomodulator with regulatory approval and a substantial randomized clinical trial database. Adverse events are mild and dominated by injection site reactions. Clinical use in COVID-19 and sepsis received attention in 2020 to 2022 with mixed efficacy results in randomized trials.

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May 10, 2026
Tesofensine

Our opinion on this compoundEstablished, active research

51/100

Triple reuptake inhibitor with a real Phase 2 weight-loss signal, now most interesting for hypothalamic obesity research

Tesofensine has one of the more interesting origin stories in obesity pharmacology: it failed in Alzheimer’s and Parkinson’s trials, and the weight loss that showed up as an adverse event became the entire rationale for repurposing. The 2008 Phase 2 published by Astrup et al. (roughly 160 patients, 24 weeks) showed approximately 10 percent body weight reduction at 0.5 mg/day, which was genuinely impressive at the time and outpaced liraglutide at standard doses by a real margin. That signal hasn’t been retracted. The problem is that the GLP-1 and dual-incretin era has since moved the goalposts considerably, and tesofensine’s headline number looks modest against semaglutide’s 15 percent and tirzepatide’s 20-plus. What was competitive in 2008 is a different conversation in 2025.

Mechanistically, balanced inhibition across all three monoamine transporters, DA, NE, and 5-HT, with similar affinity at each site hits mesolimbic reward circuits, prefrontal satiety signaling, and hypothalamic energy expenditure pathways simultaneously. That’s not a novel mechanism class. Cocaine covers this space nonselectively, sibutramine handled two of the three legs before withdrawal, and the basic pharmacology is well-characterized. What is distinctive is the 9-day plasma half-life, which creates a steady-state profile unlike anything else in the class and is genuinely useful for chronic exposure modeling in preclinical work. That kinetic fingerprint matters if you’re designing studies around sustained central monoamine elevation.

Here’s what actually makes tesofensine worth attention for a bench investigator right now: it’s not the general obesity indication. Saniona has pivoted the development program toward hypothalamic obesity, specifically Prader-Willi syndrome and craniopharyngioma-acquired hypothalamic obesity. These are populations where the normal satiety architecture is damaged or absent, which means the GLP-1 mechanism, dependent at least partly on intact hypothalamic GLP-1R signaling and downstream circuits, may not perform as expected. A central monoamine approach that compensates for broken hypothalamic regulation rather than trying to activate it is a mechanistically distinct rationale. Small populations, yes, but thats exactly the kind of clean indication-mechanism fit that produces interpretable research questions.

What we don’t love is the Phase 3 history. Enrollment paused multiple times owing to modest cardiovascular signals, blood pressure elevation, dry mouth, insomnia, and mood changes. That safety ceiling has capped tolerable dosing in ways that limit efficacy headroom. The compound isn’t scheduled in most jurisdictions, which keeps it accessible for research, but it’s also not approved anywhere, so the evidence base stops at Phase 2 with a stalled Phase 3. Evidence quality is real but thin at the top end.

We rate tesofensine established-active rather than novel-frontier. The repurposing story is nearly two decades old, the mechanism is a known class, and the incretin wave has redefined what competitive means in metabolic pharmacology. The hypothalamic obesity angle and the monoamine probe utility for energy homeostasis research keep this above mid-range, but serious investigators should go in with clear eyes about what Phase 3 stalls mean for translational confidence.

Novelty

42

Mechanism promise

60

In-category differentiation

52

Evidence quality

48

Translational signal

55

Research bench value

48

Rationale The mechanism is a known class, the 2008 Phase 2 is real but 17 years old, and the GLP-1 era has moved the goalposts on general obesity efficacy; scores mid-range because the hypothalamic obesity niche and monoamine probe utility are genuine research angles, but Phase 3 stalled and differentiation against current obesity pharmacology is limited.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

Triple monoamine reuptake inhibitor (DA, NE, 5-HT)

A triple reuptake inhibitor originally developed for Alzheimer’s and Parkinson’s disease and repurposed for obesity, advanced through Phase 2 with substantial body weight reduction relative to placebo.

Abstract

Tesofensine (NS2330; CAS 195875-84-4; molecular formula C17H23Cl2N; molecular weight 312.28) is a triple monoamine reuptake inhibitor developed by NeuroSearch in the 1990s as a candidate for Alzheimer’s disease and Parkinson’s disease (where dopamine reuptake inhibition was hypothesized to provide motor symptom relief without the on-off fluctuations of L-DOPA). The compound failed to demonstrate efficacy in the original Alzheimer’s and Parkinson’s indications; weight loss observed as an adverse event in the central nervous system trials motivated repurposing for obesity, with Phase 2 data published in 2008 showing approximately 10 percent body weight reduction at 24 weeks at the 0.5 mg dose, substantially greater than the comparator orlistat and meaningfully greater than the GLP-1 agonist liraglutide at typical doses. Mechanism is competitive inhibition at the dopamine, norepinephrine, and serotonin transporters with similar affinity at all three sites; the integrated effect is monoamine elevation in mesolimbic, prefrontal, and hypothalamic targets that suppresses appetite and increases energy expenditure. The compound was advanced through Phase 3 by NeuroSearch and partner Saniona for obesity but Phase 3 enrollment was paused multiple times owing to safety signals (modest blood pressure elevation, dry mouth, insomnia, mood changes) and the program has progressed slowly relative to the more recent GLP-1 class. Saniona has continued development for hypothalamic obesity (Prader-Willi syndrome and acquired hypothalamic obesity from craniopharyngioma surgery), with the rationale that the central monoamine elevation may compensate for hypothalamic dysfunction in these niche populations. The compound is not approved in any jurisdiction. Plasma half-life is approximately 9 days, suitable for once-daily oral administration with steady-state achieved over 4 weeks.

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May 10, 2026
Survodutide

Our opinion on this compoundNovel, promising

64/100

A dual GLP-1/glucagon agonist with real Phase 3 promise, strongest case in MASH

Look, survodutide is a serious compound in a seriously competitive space. Boehringer Ingelheim and Zealand Pharma built this as a 39-residue lipidated peptide with roughly balanced activity at both GLP-1 and glucagon receptors, and the pharmacokinetic strategy is exactly what you’d expect from this generation of metabolic peptides: a fatty acid chain for serum albumin binding, once-weekly subcutaneous dosing. Familiar architecture, but the glucagon receptor agonism is where the real story is.

Here’s the thing about adding glucagon to GLP-1: it’s not just additive appetite suppression. GLP-1 handles the central appetite and gastric emptying piece, but glucagon receptor agonism specifically drives hepatic fatty acid oxidation and increases whole-body energy expenditure in a way that GLP-1 monoagonists can’t replicate. That combination is what produced approximately 19 percent body weight reduction at 46 weeks in Phase 2 data published in 2024, numbers that land in tirzepatide territory and well ahead of semaglutide’s ceiling.

What we find genuinely compelling here is the MASH angle. Metabolic dysfunction-associated steatohepatitis is a brutal target: large unmet need, a liver disease that’s difficult to reverse, and the glucagon receptor mechanism drives hepatic fat mobilization directly. That’s mechanistically more targeted for MASH than pure GLP-1 agonism or even the GIP/GLP-1 combination in tirzepatide. The SYNCHRONIZE-2 trial is one of the more interesting things in the MASH pipeline right now, and a clean liver histology signal from that program would reposition survodutide decisively above every pure GLP-1 agent in the hepatic disease space.

The honest scoring issue for survodutide is differentiation in the obesity indication. Tirzepatide is approved and defines that category. Retatrutide adds GIP receptor agonism on top of the glucagon and GLP-1 already in survodutide’s profile, with a potentially higher efficacy ceiling. Survodutide doesnt have GIP, and if Lilly’s triple agonist survives Phase 3, that absence matters for the obesity claim. The GIP component in tirzepatide turned out to be important for insulin sensitization and weight loss ceiling; glucagon addresses energy expenditure and hepatic fat clearance but doesnt replicate the same glucose-handling angle.

That said, Phase 3 SYNCHRONIZE obesity data aren’t in yet, and the MASH program is genuinely differentiated from anything tirzepatide or semaglutide is positioned to do. Survodutide also clearly outclasses cotadutide on pharmacokinetic profile. We think this is a compound worth active tracking, especially heading into the 2026 to 2027 regulatory submission window. Strong Phase 2 human data, a coherent dual mechanism with a real hepatic rationale, and unmet-need positioning in MASH. It just isn’t the category-defining move that tirzepatide was when the GIP controversy was still live.

Novelty

60

Mechanism promise

70

In-category differentiation

65

Evidence quality

58

Translational signal

68

Research bench value

58

Rationale Solid Phase 2 human efficacy (~19% weight loss at 46 weeks) and a mechanistically coherent glucagon-driven MASH angle push scores up, but survodutide competes directly with tirzepatide in obesity and lacks GIP receptor agonism; pending Phase 3 readouts keep evidence and translational scores from reaching the high 70s.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

GLP-1 and glucagon receptor dual agonist

A long-acting GLP-1 and glucagon receptor dual agonist developed by Boehringer Ingelheim and Zealand Pharma, advanced through Phase 3 in obesity and MASH.

Abstract

Survodutide (BI 456906; SAR-441255; CAS 2403761-22-2 mass) is a long-acting GLP-1 receptor and glucagon receptor dual agonist developed by Boehringer Ingelheim in collaboration with Zealand Pharma. The compound is a 39-residue lipidated peptide based on the glucagon and GLP-1 sequences, with selective potency approximately equivalent at the two receptors and with a fatty acid chain modification enabling once-weekly subcutaneous administration through serum albumin binding (the same pharmacokinetic strategy used by semaglutide, liraglutide, and tirzepatide). The dual-agonist mechanism produces synergistic effects on body weight: GLP-1 receptor agonism reduces appetite and slows gastric emptying through hypothalamic and brainstem pathways (the dominant mechanism shared with semaglutide and other GLP-1 monoagonists), while glucagon receptor agonism increases hepatic fatty acid oxidation and energy expenditure, mobilizing hepatic and visceral fat in a manner not achieved by GLP-1 monoagonism. Phase 2 obesity results published in 2024 reported up to approximately 19 percent body weight reduction at 46 weeks at the highest dose, similar to the magnitude observed with tirzepatide and substantially greater than semaglutide. The compound is in active Phase 3 development in obesity (SYNCHRONIZE program) and MASH (SYNCHRONIZE-2; metabolic dysfunction-associated steatohepatitis) with anticipated regulatory submissions in 2026 to 2027. Side effect profile parallels other GLP-1-class agents (nausea, vomiting, diarrhea, occasional gastroparesis) with the additional consideration of glucagon-related effects (modest heart rate elevation, occasional hypoglycemia masked by reduced insulin sensitivity, and consideration of bilirubin elevation). Survodutide is distinct from retatrutide (Eli Lilly’s triple GLP-1/GIP/glucagon agonist) in lacking GIP receptor agonism and from cotadutide (AstraZeneca’s GLP-1/glucagon dual) in pharmacokinetic profile and clinical positioning.

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May 10, 2026
Humanin

Our opinion on this compoundEstablished, active research

56/100

Founding mitochondrial-derived peptide with elegant multi-target biology but thin human translation

Look, humanin is one of those compounds where the biology is genuinely exciting and the clinical story is genuinely disappointing, and you have to hold both of those at the same time. Discovered in 2001 by Hashimoto’s group at Keio in a screen for factors that could rescue neurons from amyloid-beta toxicity, it’s the founding member of the mitochondrial-derived peptide family, a class we now know includes MOTS-c, the SHLP peptides, and gau. The fact that the mitochondrial genome encodes bioactive signaling peptides at all was the paradigm-interesting discovery. Humanin was the first proof of that concept.

The mechanism is what keeps us interested. Humanin isn’t doing one thing. It’s binding BAX and BIM directly in the cytoplasm to suppress pro-apoptotic signaling, engaging the CNTFR-WSX-1-gp130 heterotrimeric receptor complex on the membrane, and activating FPR2, a receptor with broad relevance to inflammation and cytoprotection. Multi-compartment, multi-receptor, with downstream effects that span neuroprotection, insulin sensitivity in rodent obesity models, and cytoprotection against ischemic and chemotherapy-induced injury. Thats a genuinely interesting pharmacological signature. The S14G substitution (HNG) delivers roughly 1000-fold potency improvement in neuroprotection assays and is the right research-grade form to reach for if you’re running in vitro or rodent work.

The evidence picture is solid at the preclinical level. Multiple labs have replicated the core anti-apoptotic and neuroprotective findings, and the rodent metabolic data is reasonably clean. What’s missing is the human side. Clinical development has been limited, the PK characterization in humans is sparse, and there are no phase 2 readouts to point at. Observational work has established that circulating humanin levels decline with age and track with disease-associated phenotypes, but that’s a far cry from interventional data. We’ve seen this story before with other peptides: strong rodent, weak translation, and a long wait for someone to run a proper human pharmacology study.

As a bench tool, humanin earns its place. It’s the reference probe for MDP biology and an essential comparator if you’re working anywhere near the mitochondrial-derived peptide space. The BAX/BIM binding angle also makes it useful as a probe for Bcl-2 family apoptosis work, and the CNTF receptor engagement gives it orthogonal utility in neurotrophin biology. What we like is the specificity and the multi-target readouts you get with HNG. What we don’t like is the clinical silence after 25 years of preclinical work. Humanin is firmly in the category of compounds that deserve more rigorous human pharmacology than they’ve gotten. Whether that will happen is still an open question.

Novelty

52

Mechanism promise

74

In-category differentiation

65

Evidence quality

42

Translational signal

35

Research bench value

65

Rationale Humanin is the reference compound for the MDP class, with a genuinely sophisticated multi-receptor mechanism and solid multi-lab preclinical base, but it’s been around since 2001 and clinical development has stalled; the score reflects strong bench utility and mechanism quality offset by weak translational signal and diminishing novelty relative to newer MDPs like MOTS-c.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

24-residue mitochondrial-derived peptide (MDP)

A 24-amino-acid peptide encoded within the 16S rRNA of the mitochondrial genome, identified as a neuroprotective and metabolic factor with broad anti-apoptotic activity.

Abstract

Humanin (Met-Ala-Pro-Arg-Gly-Phe-Ser-Cys-Leu-Leu-Leu-Leu-Thr-Ser-Glu-Ile-Asp-Leu-Pro-Val-Lys-Arg-Arg-Ala; molecular weight 2687.27 free peptide; CAS 330936-69-1) is a 24-residue peptide encoded within the 16S ribosomal RNA gene of the mitochondrial genome, identified by Yuichi Hashimoto and colleagues at Keio University in 2001 in a screen for anti-apoptotic factors that protected against amyloid-beta-induced neuronal death. Humanin is the founding member of the mitochondrial-derived peptide (MDP) family, a class of peptides encoded within mitochondrial DNA and translated from short open reading frames in mitochondrial RNAs; other family members include MOTS-c (KDC-MN-008), the SHLP family (small humanin-like peptides 1 through 6), and gau (gene antisense ubiquitous). The pharmacological signature of humanin includes anti-apoptotic activity through binding the BAX and BIM Bcl-2 family pro-apoptotic proteins, suppression of caspase activation, neuroprotection against amyloid-beta, prion peptide, and ALS-associated SOD1 toxicity in rodent and cell culture models, modulation of metabolic phenotypes (improved insulin sensitivity in rodent obesity models), and cytoprotection in models of myocardial ischemia and chemotherapy-induced toxicity. Receptors include the heterotrimeric ciliary neurotrophic factor (CNTF) receptor complex (CNTFR-WSX-1-gp130), the formyl peptide receptor 2 (FPR2), and direct cytoplasmic protein-protein interactions with BAX/BIM. The S14G analog of humanin (HNG; gly substituted for ser at position 14) is approximately 1000-fold more potent in neuroprotection assays and is the principal research-grade analog used in pharmacology studies. The compound is research-grade with no regulatory approval; clinical development has been limited despite the strong preclinical signal, attributed in part to the narrow therapeutic window for neurodegenerative disease drugs and the sparse human pharmacokinetic characterization.

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May 10, 2026
GDF-11

Our opinion on this compoundOverhyped vs evidence

34/100

Heavily contested rejuvenation factor; replication crisis and myostatin confusion undermine the core premise

Look, GDF-11 is one of the most instructive cautionary tales in recent aging biology. The 2013 Wagers and Lee parabiosis papers published in Cell generated enormous excitement: here, apparently, was a circulating youth factor that reversed age-related cardiac hypertrophy and improved skeletal muscle regeneration when old mice were connected to young blood. GDF-11 levels appeared to decline with age, and restoring them seemed to roll back the clock. The press coverage was extraordinary. The follow-up funding was substantial.

Then the replication work came in. The Glass lab at Eli Lilly and subsequent independent groups identified a core methodological problem: the immunoassays used in the original studies did not adequately distinguish GDF-11 from myostatin. These two proteins share approximately 90 percent amino acid identity in their mature domains and bind the same receptors, ActRIIA and ActRIIB, signaling through the same SMAD2/3 downstream pathway. When the assay confusion was corrected, the evidence that circulating GDF-11 actually declines with age largely evaporated. And when recombinant GDF-11 was administered at higher doses in independent labs, the effects looked less like rejuvenation and more like muscle wasting, which is exactly what you’d predict from a myostatin-homologous protein acting on the same receptor.

We’re not calling this decisively dead. A handful of groups continue to report modest pro-cardiac and pro-cognitive effects at carefully titrated, low doses, and the question of why GDF-11 and myostatin might produce divergent tissue-specific outputs despite sharing a receptor is genuinely open. Propeptide regulation and context-dependent SMAD activation are plausible explanatory angles. That question has real research value. But the original young-blood-factor story is badly damaged, theres no active clinical development pipeline, and no human translational data worth citing.

What makes GDF-11 a legitimate object of study right now is precisely its contested status. If your program touches parabiosis biology, TGF-beta superfamily receptor specificity, or aging biomarker methodology, GDF-11 is a real probe. The myostatin confusion problem has forced investigators in this space to develop much more rigorous assay standards, which is a genuine contribution to the field even if it emerged from a failed replication. Its a compound that teaches methodology as much as it illuminates biology.

What we don’t like: no human translational arrow, no consensus on whether the core rejuvenation claim survives scrutiny, and a track record of independent labs failing to replicate the headline findings. For a library focused on compelling frontier targets, GDF-11 scores as a cautionary and methodologically useful compound rather than an exciting one. Study it if your work touches parabiosis or TGF-beta superfamily receptor biology. Otherwise, there are sharper tools with cleaner evidence.

Novelty

45

Mechanism promise

35

In-category differentiation

35

Evidence quality

28

Translational signal

18

Research bench value

45

Rationale GDF-11 scored low across evidence and translational axes because independent replication failed to confirm the core age-decline/rejuvenation claims, the immunoassay cross-reactivity with myostatin is a fundamental methodological problem, and there is no human data or active clinical development. Bench value is modest but real for investigators working on TGF-beta superfamily biology, parabiosis methodology, or propeptide regulation in aging tissue.

Editorial commentary from Kodiac biolabs. Not a recommendation, not clinical advice. Research use only.

TGF-beta superfamily growth differentiation factor

A growth differentiation factor in the TGF-beta superfamily originally implicated in parabiosis-mediated rejuvenation and subsequently a focus of contested replication studies in cardiac and skeletal muscle aging.

Abstract

GDF-11 (growth differentiation factor 11; bone morphogenetic protein 11, BMP-11; CAS 268544-12-9; mature peptide molecular weight approximately 12.5 kDa as a homodimer) is a member of the transforming growth factor beta (TGF-beta) superfamily, closely related to myostatin (GDF-8) with which it shares approximately 90 percent amino acid identity in the mature C-terminal domain. The compound came to prominence in 2013 when a heterochronic parabiosis study by Amy Wagers and Richard Lee at the Harvard Stem Cell Institute identified GDF-11 as a putative young-blood-borne rejuvenation factor that reversed age-related cardiac hypertrophy when administered to old mice. Subsequent studies extended the proposed rejuvenation activity to skeletal muscle and the central nervous system. The original GDF-11 papers triggered substantial follow-up research and substantial contested replication: independent groups (notably the Glass laboratory at Eli Lilly and the Wagers laboratory’s own subsequent work) reported that the original immunoassays did not adequately distinguish GDF-11 from myostatin, that circulating GDF-11 levels do not in fact decline with age, and that recombinant GDF-11 administered to old mice produces muscle wasting at high doses (consistent with the myostatin-like activity expected from the structural homology) rather than rejuvenation. The contested literature has not produced consensus; some groups continue to report modest pro-cardiac and pro-cognitive effects of GDF-11 at carefully titrated doses, while others find no effect or harmful effects. Mechanism is canonical TGF-beta superfamily signaling through ActRIIA/B receptors and downstream SMAD2/3 transcription factor activation; GDF-11 and myostatin share the same receptor and signaling pathway, distinguishing them principally through tissue-specific expression patterns and post-translational propeptide regulation. The compound is research-grade with no regulatory approval and no active clinical development. Investigators studying GDF-11 should be aware of the contested replication literature and the importance of distinguishing GDF-11 from myostatin in immunoassays.

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May 10, 2026

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