High evidence 0Moderate evidence 3Low evidence 8Very low evidence 0
Multiple (review) is shown as a marketed evidence record where applicable. Findings describe observed research and regulatory records; they do not provide treatment advice.
Multiple (review)MARKETED
hepatic-mashNot directional
Moderate evidence
FIELD-WIDE SURROGATE-vs-HARD-OUTCOME GAP (the spine of the outcomes story): every incretin MASH approval or positive trial to date rests on 1-2 yr HISTOLOGICAL...
SourceWang Y, Zhou Y et al. Efficacy of GLP-1-based therapies on MASLD and MASH: systematic rev...Source
Full findingFIELD-WIDE SURROGATE-vs-HARD-OUTCOME GAP (the spine of the outcomes story): every incretin MASH approval or positive trial to date rests on 1-2 yr HISTOLOGICAL SURROGATES (MASH resolution; >=1-stage fibrosis improvement) accepted by FDA under accelerated approval (subpart H) as REASONABLY LIKELY to predict benefit. NO incretin has yet shown a reduction in HARD clinical liver outcomes (progression to cirrhosis, decompensation, HCC, transplant, liver-related mortality); those readouts are years away (e.g. ESSENCE part 2 ~240 wk). Retatrutide sits one tier below even this: imaging-surrogate (liver-fat) data only, not histological surrogates.
Fundingacademic - Chinese government (Ministry of Science and Technology grant 2017ZX09303001; National Natural Science Foundation of China grant 82370814)
Scope limitssurrogate/exploratory endpoint
Comparatorsplacebo
Multiple (review)MARKETED
hepatic-mashNot directional
Moderate evidence
WEIGHT-MEDIATED vs DIRECT-HEPATIC question for OUTCOMES: it remains unresolved whether incretin MASH improvement is fully explained by weight loss or whether there is...
SourceSynthesis across class MASH datasets (reta Sanyal Nat Med 2024 LF tied to weight; survodu...
Full findingWEIGHT-MEDIATED vs DIRECT-HEPATIC question for OUTCOMES: it remains unresolved whether incretin MASH improvement is fully explained by weight loss or whether there is a weight-INDEPENDENT hepatic increment, particularly for glucagon-receptor-containing agents (whose GCGR arm drives hepatic lipid oxidation and may act partly independently of weight). For reta specifically, the phase-2a substudy reported liver-fat reductions significantly related to weight and abdominal-fat loss, so a weight-independent hepatic effect of its glucagon arm is NOT established for outcomes - it is the open question.
PopulationClass-level mechanistic-attribution question applied to OUTCOMES; reta glucagon arm the specific open case.
Histology-endpoint review: GLP-1RA-based agents improve MASH disease activity; tirzepatide and survodutide additionally show fibrosis-reduction signals; semaglutide...
SourceZafer M, Tavaglione F, Romero-Gómez M, Loomba R. Review: GLP-1 RAs and glucagon/GIP/GLP-1...Source
Full findingHistology-endpoint review: GLP-1RA-based agents improve MASH disease activity; tirzepatide and survodutide additionally show fibrosis-reduction signals; semaglutide phase-3 interim confirmed steatohepatitis improvement and potential fibrosis benefit.
PopulationComprehensive review of phase 2 (and interim phase 3) MASH trials with histology endpoints
Fundingacademic-NIH (NCATS/NIDDK/NHLBI/NIAAA) and John C Martin Foundation
Scope limitsmagnitude web/secondary-sourced
Multiple (review)MARKETED
hepatic-mashNot directional
Low evidence
COMPENSATED-CIRRHOSIS (MASH F4) FRONTIER - EVIDENCE GAP. The landmark registrational MASH programmes systematically EXCLUDE established cirrhosis (ESSENCE F2/F3;...
SourceDerived from ESSENCE and MAESTRO-NASH inclusion criteria, both of which exclude F4 cirrho...
Full findingCOMPENSATED-CIRRHOSIS (MASH F4) FRONTIER - EVIDENCE GAP. The landmark registrational MASH programmes systematically EXCLUDE established cirrhosis (ESSENCE F2/F3; MAESTRO-NASH F1B-F3). As of this gather no incretin (GLP-1 mono, GLP-1/glucagon dual, or triple) has a published trial showing histological OR clinical benefit in compensated MASH cirrhosis or portal hypertension. This row FLAGS the gap, it does not assert a finding.
Populationn/a - characterises absence of F4 evidence; ESSENCE (F2/F3) and MAESTRO-NASH (F1B-F3) cited as the exclusion evidence.
Fundingacademic/independent analysis (manufacturer not study sponsor; per-study COI not individually audited)
SourceFDA accelerated-approval framework for MASH (subpart H; histological surrogate 'reasonabl...
Full findingNATURAL-HISTORY / REGULATORY CONTEXT: MASH fibrosis stage predicts liver-related clinical outcomes (decompensation, HCC, liver death), risk rising steeply at advanced stages - which is why histological fibrosis improvement was adopted as an endpoint. CRUCIAL DISTINCTION: the accepted surrogates (MASH resolution; >=1-stage fibrosis improvement) are validated as 'REASONABLY LIKELY to predict' benefit (the statutory basis for FDA accelerated approval), NOT as PROVEN clinical-outcome surrogates. Confirmatory hard-outcome trials are required to convert reasonably-likely to proven, and for the incretin class those readouts have not yet reported.
Populationn/a - regulatory/natural-history framing applicable to the whole MASH field.
Fundingacademic/independent analysis (manufacturer not study sponsor; per-study COI not individually audited)
Scope limitssurrogate/exploratory endpoint
Multiple (review)MARKETED
hepatic-mashMixed
Low evidence
BALANCED OBSERVATION on the glucagon-anti-fibrosis hypothesis. POLE FOR: the mechanistic rationale (hepatic GCGR action on lipid oxidation/stellate biology) plus...
SourceCross-agent observation from PMID 38847460 (survodutide), 38856224 (tirzepatide), 4123779...
Full findingBALANCED OBSERVATION on the glucagon-anti-fibrosis hypothesis. POLE FOR: the mechanistic rationale (hepatic GCGR action on lipid oxidation/stellate biology) plus survodutide's strong MASH-improvement result and rodent dual>mono liver-fat data. POLE AGAINST: on the FIBROSIS endpoint specifically the human evidence does NOT show glucagon-containing duals out-performing GIP/GLP-1 or GLP-1-mono - pemvidutide (a glucagon dual) MISSED fibrosis at 24 wk, tirzepatide (NO glucagon) posted the numerically highest fibrosis rates, and GLP-1-mono semaglutide showed its own fibrosis signal in ESSENCE. Cross-trial comparison is confounded by fibrosis stage, duration, endpoint definitions and weight loss.
PopulationCross-agent synthesis of published phase-2 MASH histology trials (survodutide, SYNERGY-NASH, IMPACT, semaglutide ph2b/ESSENCE).
Fundinganalyst cross-agent synthesis (no study funding; not a sponsored output)
Scope limitsNEUTRAL on science, judgemental on evidence. VERDICT: the evidence is TOO HETEROGENEOUS to conclude that glucagon-containing co-agonists deliver a stronger FIBROSIS-improvement signal than GLP-1-mono. The cleanest test available (pemvidutide's glucagon dual MISSING fibrosis at 24 wk while tirzepatide without glucagon posted the highest fibrosis numbers) actively cuts against a simple glucagon=anti-fibrotic story at the fibrosis endpoint. KEY CONFOUND: all these agents drive large weight loss (itself MASH-improving), so no trial separates a DIRECT hepatic glucagon effect from a weight-mediated one. Glucagon's apparent edge (where it exists) is clearer on liver-FAT/disease-activity than on FIBROSIS. Reta relevance: reta is the most potent triple but has NO MASH histology trial - this pattern must NOT be read as a prediction of observed reta fibrosis outcomes.
Thin or bounded evidence here means uncertainty remains visible. It is not evidence that an effect has been ruled out.
Multiple (review)MARKETED
Body compositionMixed
Low evidence
ADAPTIVE-POLE anchor (both poles preserved): reported lean-mass loss as a proportion of weight lost is heterogeneous (40-60% in some studies, <=15% in others); on...
SourceNeeland IJ et al., Diabetes Obes Metab, 2024Source
Full findingADAPTIVE-POLE anchor (both poles preserved): reported lean-mass loss as a proportion of weight lost is heterogeneous (40-60% in some studies, <=15% in others); on contemporary evidence including MRI muscle-volume work the skeletal-muscle changes appear largely ADAPTIVE (commensurate with the weight loss achieved, with improved insulin sensitivity and reduced muscle fat infiltration suggesting improved muscle QUALITY), rather than pathological wasting. Older age / disease severity flagged as risk modifiers.
PopulationNarrative review of trial + MRI-based evidence on GLP-1RA and dual GLP-1/GIP effects on lean body mass and muscle health in overweight/obesity.
Fundingacademic/independent analysis (manufacturer not study sponsor; per-study COI not individually audited)
Scope limitsADAPTIVE pole. KEY caveat the authors themselves make: DXA 'lean mass' includes organ, bone, fluid, so 'lean preserved' is NOT 'muscle/function preserved'; the adaptive reading rests on MRI muscle-volume + quality inference, NOT strength/function endpoints (which are largely absent, see C-CLASS-BODYCOMP-08). This is the thread-5 T5-014 cross-ref. Counter-pole: C-CLASS-BODYCOMP-06. Companion paper Linge/Birkenfeld/Neeland Circulation 2024 (PMID 39401279) makes the same case; folded here to avoid a duplicate row. COI (validation): co-author J. Linge is employed by AMRA Medical (a commercial MRI muscle-composition analytics firm), directly relevant to the MRI-based 'muscle quality preserved / adaptive' inference. CONFIDENCE (Council Evidence-grader + Red-team): this adaptive/muscle-quality inference is held at NO HIGHER confidence than the caution pole (C-CLASS-BODYCOMP-06); it is down-weighted because the MRI-composition methodology underpinning the 'quality preserved' claim is the AMRA-employed co-author's commercial product. Improved muscle quality / reduced IMAT has NOT been shown to offset quantity loss in any function endpoint (none exist), and IMAT reduction may track total fat loss rather than a muscle-specific effect.
Multiple (review)MARKETED
Body compositionNot directional
Low evidence
DEFINITIONAL YARDSTICK: the ESPEN/EASO consensus defines sarcopenic obesity as excess adiposity PLUS low muscle MASS PLUS low muscle FUNCTION, with a two-step...
SourceDonini LM, Busetto L, Bischoff SC, Barazzoni R, Prado CM et al. (ESPEN/EASO Consensus), O...Source
Full findingDEFINITIONAL YARDSTICK: the ESPEN/EASO consensus defines sarcopenic obesity as excess adiposity PLUS low muscle MASS PLUS low muscle FUNCTION, with a two-step diagnostic pathway that confirms via a muscle-FUNCTION test (e.g. strength) before a mass measure. By this standard, calling incretin lean-mass loss 'sarcopenia' REQUIRES a demonstrated FUNCTION deficit, which the trials have not measured.
PopulationESPEN + EASO international expert consensus statement.
Fundingacademic/independent analysis (manufacturer not study sponsor; per-study COI not individually audited)
Scope limitsThe NEUTRAL yardstick for the harm-vs-adaptive debate: function-first diagnosis means DXA mass loss alone does not equal sarcopenia. Co-authored by Prado and Barazzoni (sarcopenic-obesity authorities). Predates the GLP-1 surge; applied here as the standard, not as a drug study. Graded LOW (expert consensus/guidance, no pooled estimate; Council Evidence-grader). BIDIRECTIONAL (Council Red-team): by ESPEN/EASO criteria, DXA mass loss alone CANNOT be called sarcopenia without a demonstrated function deficit, AND the absence of measured function CANNOT be called muscle-safe either - the class is currently undiagnosable in both directions. This yardstick governs adjudication of the harm-vs-adaptive poles.
Multiple (review)MARKETED
Body compositionNot directional
Low evidence
Mechanistic / landscape anchor: incretin weight loss is accompanied by fat-free-mass loss (heterogeneously ~15% to 40-60% of weight lost), motivating adjuncts that...
SourceAimelet V & Holst JJ, Diabetes Obes Metab, 2025Source
Full findingMechanistic / landscape anchor: incretin weight loss is accompanied by fat-free-mass loss (heterogeneously ~15% to 40-60% of weight lost), motivating adjuncts that preserve or add lean mass. The myostatin/activin-ActRII axis is a negative regulator of muscle growth; blocking it (at the receptor, bimagrumab; at ligands, trevogrumab/anti-GDF8, garetosmab/anti-activin A, apitegromab/anti-latent-myostatin) repartitions loss toward fat and can add lean mass. SARMs (enobosarm) anabolise via androgen-receptor selectivity. Bimagrumab and enobosarm have the most human data; most agents remain early-phase with limited long-term safety.
PopulationNarrative reviews of preclinical + phase-2/3 human studies of lean-mass-preserving pharmacotherapy during GLP-1RA / dual-agonist weight loss.
Fundingacademic (Aimelet & Holst, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen; no external funding statement; author COIs disclosed)
Scope limitsanimal data; human relevance uncertain
Thin or bounded evidence here means uncertainty remains visible. It is not evidence that an effect has been ruled out.
Multiple (review)MARKETED
Maintenance and regainNot directional
Low evidence
INTERPRETIVE NOTE (neutral framing): authoritative bodies frame obesity as a chronic, relapsing, progressive disease (World Obesity Federation; joint World Heart...
Full findingINTERPRETIVE NOTE (neutral framing): authoritative bodies frame obesity as a chronic, relapsing, progressive disease (World Obesity Federation; joint World Heart Federation / World Obesity Federation). This is the backdrop the withdrawal trials are read against: if obesity is chronic and relapsing, regain on stopping is the expected disease course and indefinite MAINTENANCE of some kind is implied (which could be pharmacological, surgical or intensive behavioural). The trials evidence only that DRUG continuation maintains DRUG-induced loss - NOT that lifelong drug therapy specifically is required or net-beneficial over a decade scale. Recorded as framing context, NOT a verdict on whether any individual should be on lifelong therapy.
PopulationWorld Obesity Federation position statement (2017) and joint WHF/WOF position paper (2022).
Fundingacademic/independent analysis (manufacturer not study sponsor; per-study COI not individually audited)
Scope limitsNeutral interpretive note. The 'chronic relapsing disease' framing reframes regain-on-stopping as expected disease relapse rather than treatment failure. Graded low (position/consensus, not primary data). COI / INDEPENDENCE (Council Evidence-grader + Red-team): the WOF (2017) and WHF/WOF (2022) are obesity-medicine field bodies with substantial pharmaceutical-industry funding ties, and the position-statement authors OVERLAP with the sponsored withdrawal-trial author lists (e.g. Wilding, also lead author of STEP-1 / C-SEMAGLUTIDE-MAINT-02). The 'chronic disease -> continued therapy' framing is CONCORDANT with the manufacturers' commercial interest in continued treatment; treat as an interpretive stance, NOT independent evidence. Validation: PMID 28489290 + 36007112 confirmed.
Thin or bounded evidence here means uncertainty remains visible. It is not evidence that an effect has been ruled out.
Multiple (review)MARKETED
Obstructive sleep apnoeaNot directional
Low evidence
INDICATION LANDSCAPE / REGULATORY CONTEXT: OSA is now a validated incretin indication path - tirzepatide became the first-ever drug approved for OSA (FDA, Dec 2024) on...
SourceGiblin K et al. Design of the TRIUMPH phase-3 retatrutide programme. Diabetes Obes Metab ...Source
Full findingINDICATION LANDSCAPE / REGULATORY CONTEXT: OSA is now a validated incretin indication path - tirzepatide became the first-ever drug approved for OSA (FDA, Dec 2024) on the SURMOUNT-OSA AHI evidence, and Lilly IS pursuing retatrutide along the same path (TRIUMPH OSA cohorts with AHI as a primary endpoint, named as a registrational complication in the TRIUMPH design paper). Reta's place in the path is signalled-and-registered but as-yet-unproven (no OSA results, no indication).
The Echo Compendium