TRANSCEND-CKD: What Retatrutide's Kidney-Function Trial Is Actually Testing
TL;DR: TRANSCEND-CKD tests retatrutide's effect on measured GFR in 146 CKD patients; design published, 24-week results still pending.
What Is TRANSCEND-CKD?
TRANSCEND-CKD is a Phase 2b, double-blind, placebo-controlled mechanistic trial (ClinicalTrials.gov identifier NCT05936151) sponsored by Eli Lilly to test whether retatrutide, the company's investigational GIP/GLP-1/glucagon triple receptor agonist, improves directly measured kidney function in adults with overweight or obesity and chronic kidney disease (CKD).[1] The trial's rationale, design and baseline characteristics were published as a standalone paper in Nephrology Dialysis Transplantation in late 2025, ahead of any efficacy readout.[1]
This is a separate, mechanistic dataset from retatrutide's Phase 3 TRIUMPH obesity programme covered in our retatrutide research overview, and from the kidney-outcomes component of the much larger TRIUMPH-Outcomes cardiovascular trial, which is not expected to read out before 2028. TRANSCEND-CKD is designed to answer a narrower, more mechanistic question first: does retatrutide measurably change kidney filtration in a population selected specifically for reduced kidney function.
Velox Peptides supplies retatrutide as an HPLC-verified (≥99% purity) lyophilised reagent for in vitro research use only. View the product page →
Why Test a Weight-Loss Drug's Effect on the Kidney?
The trial's stated rationale rests on a specific physiological hypothesis: excess peri-renal and intra-abdominal fat can mechanically compress the kidney's glomeruli, impairing normal filtration hemodynamics independent of diabetes-related kidney damage.[1] Because retatrutide produces substantial fat loss through combined GIP, GLP-1 and glucagon receptor agonism, the authors hypothesise that reducing this peri-renal fat burden could relieve glomerular compression and improve measured kidney function, independent of any separate effect on diabetes or blood pressure.[1]
This mechanistic framing distinguishes TRANSCEND-CKD from typical diabetic-kidney-disease drug trials, which usually test agents in patients whose kidney disease is presumed to be driven primarily by chronic hyperglycaemia. TRANSCEND-CKD instead enrolled patients with and without type 2 diabetes, allowing the investigators to examine whether any renal-function effect is independent of glycaemic status.
How Was the Trial Designed?
Eligible participants had overweight or obesity together with CKD stage G3, defined in the protocol as an estimated glomerular filtration rate (eGFR) of 25–75 mL/min/1.73m², with or without type 2 diabetes.[1] Participants were randomised 1:1 to once-weekly subcutaneous retatrutide, titrated to the maximum tolerated dose up to 12mg, or matched placebo.[1]
The primary endpoint is change from baseline in iohexol-clearance measured glomerular filtration rate (mGFR) at 24 weeks — a direct exogenous-marker clearance technique that is more precise than the creatinine-based eGFR equations used in routine clinical practice, though considerably more resource-intensive to administer, which is why it is reserved for mechanistic trials of this kind rather than large outcome studies.[1]
Nephrol Dial Transplant 2026;41(6):1058–1068.
Source: doi.org/10.1093/ndt/gfaf230 · ClinicalTrials.gov NCT05936151
What Do the Published Baseline Characteristics Show?
The published paper reports only baseline data collected before treatment began — it is a description of the study population, not an efficacy result. At randomisation, the 146 participants had a mean iohexol-measured mGFR of 49.3 mL/min/1.73m², a mean age of 65.1 years, mean BMI of 35.7, and 37.7% had type 2 diabetes; median baseline urine albumin-to-creatinine ratio (UACR) was 14.0 mg/g (interquartile range 6.0–69.0).[1]
Kidney function at entry
Mean baseline mGFR of 49.3 mL/min/1.73m² places the study population squarely within moderate CKD (stage G3), consistent with the protocol's eGFR 25–75 enrolment window.
Mixed diabetes status
With just over a third of participants having type 2 diabetes and the remainder not, the trial is positioned to examine whether any kidney-function signal is independent of diabetic kidney disease specifically.
Wide albuminuria spread
The interquartile range of 6.0–69.0 mg/g for baseline UACR spans normal-to-moderately-elevated albuminuria, indicating a population with varying degrees of kidney damage rather than a single narrow disease severity band.
None of these figures describe a treatment effect. They establish what the trial population looked like before receiving retatrutide or placebo, which is the necessary context for interpreting whatever efficacy results follow.
How Does This Fit With Retatrutide's Other Metabolic Trial Data?
Separate from the completed TRIUMPH obesity programme
TRIUMPH-1 through TRIUMPH-4 and TRANSCEND-T2D-1 measured weight loss and glycaemic control as primary endpoints in general obesity and type 2 diabetes populations, not kidney function specifically. See our retatrutide research overview for that dataset.
Distinct from post-hoc kidney signals in earlier Phase 2 data
Earlier retatrutide Phase 2 post-hoc analyses in obesity and diabetes cohorts reported reductions in urine albumin-to-creatinine ratio and eGFR gains, but those were secondary, exploratory analyses of trials not designed around kidney function. TRANSCEND-CKD is the first retatrutide trial purpose-built and powered around a kidney-function primary endpoint.
Smaller and earlier-stage than TRIUMPH-Outcomes
The much larger, event-driven TRIUMPH-Outcomes cardiovascular trial (tracked in our FDA & MHRA approval timeline guide) includes kidney outcomes within its composite endpoint but enrols roughly 13,000 participants and is not expected to read out before 2028. TRANSCEND-CKD, at 146 participants over 24 weeks, is a much smaller mechanistic study designed to generate an earlier physiological signal.
What Are the Limitations Researchers Should Note?
Several caveats matter for anyone citing this trial. First, only the design and baseline-characteristics paper has been published; no topline 24-week efficacy data has been reported as of this article's publication, and the direction or magnitude of any GFR change remains unknown. Second, at 146 participants this is a Phase 2b mechanistic study, not a Phase 3 registration trial, and it is not designed or powered to support a labelling claim on its own. Third, the iohexol-clearance methodology used here, while precise, is a research-grade measurement not used in routine clinical nephrology, so any published result will need translation into more familiar eGFR terms before it is clinically actionable. Fourth, retatrutide itself remains an unlicensed, investigational compound with no MHRA or FDA approval for any indication, and nothing in this trial's design changes that regulatory status.
None of this constitutes evidence of any kidney, weight-loss, or metabolic effect of retatrutide in humans beyond what has been formally reported, and none of it describes any property of Velox Peptides' research-grade retatrutide product, which is supplied strictly for in vitro laboratory use and carries no therapeutic or health-benefit claims.
Velox Peptides Supply Information
Retatrutide is supplied as a research reagent only. It is not a medicine and has not been evaluated by the MHRA or FDA. Not for human or veterinary use. See our Research Use Policy and MHRA Statement.
References
- Rationale, design and baseline characteristics of the TRANSCEND-CKD trial of retatrutide in patients with chronic kidney disease. Nephrol Dial Transplant 2026;41(6):1058–1068. doi.org/10.1093/ndt/gfaf230.
- Eli Lilly and Company. A Study of Retatrutide (LY3437943) on Renal Function in Participants With Overweight or Obesity and Chronic Kidney Disease With or Without Type 2 Diabetes. ClinicalTrials.gov identifier NCT05936151.
- Velox Peptides. Retatrutide's Phase 3 Package Is Complete: Lilly Q2 2026 Earnings. See our Q2 2026 earnings guide for the wider TRIUMPH programme status.
Frequently Asked Questions
What is TRANSCEND-CKD?
TRANSCEND-CKD (NCT05936151) is a Phase 2b, double-blind, placebo-controlled mechanistic trial testing whether retatrutide improves measured kidney function in adults with overweight or obesity and chronic kidney disease (eGFR 25-75 mL/min/1.73m²), with or without type 2 diabetes. Its design and baseline characteristics were published in Nephrology Dialysis Transplantation in 2025.
How is kidney function measured in this trial?
The primary endpoint is iohexol-clearance measured glomerular filtration rate (mGFR) at 24 weeks, a direct exogenous-marker clearance method considered more precise than the creatinine-based eGFR equations used in routine clinical care.
What were the baseline characteristics of the trial population?
The published baseline paper describes 146 randomised participants with a mean iohexol mGFR of 49.3 mL/min/1.73m², mean age 65.1 years, mean BMI 35.7, and 37.7% with type 2 diabetes; median baseline urine albumin-to-creatinine ratio was 14.0 mg/g. These are baseline characteristics only, not outcome results.
Have topline results been reported yet?
No. As of this article's publication, only the trial's rationale, design and baseline characteristics have been published. Topline 24-week efficacy results have not yet been reported. This is a Phase 2b mechanistic study, not a registration trial, and is separate from the larger TRIUMPH-Outcomes cardiovascular and kidney composite trial expected to read out from 2028.
Where can I buy retatrutide for research in the UK?
Velox Peptides supplies retatrutide (LY3437943) for in vitro research use in the UK. It is HPLC-verified at ≥99% purity, supplied as lyophilised powder in 10mg and 20mg vials, and dispatched from the UK within 24 hours. See our Research Use Policy before purchasing. Order here →