SAR441255

updated

SAR441255 is Sanofi's exendin-4-based peptide agonist of the GLP-1, glucagon and GIP receptors, with no matching FDA application as of 9 October 2026. Its first-in-human results were published in Cell Metabolism in December 2021, showing improved glycemic control in healthy subjects after single doses. No weight result in people, no multiple-dose study and no later registered trial were found.

GLP-1, glucagon and GIP receptor triagonist peptide

  • SAR441255 is a synthetic exendin-4-based peptide agonist of the GLP-1, glucagon and GIP receptors, developed by Sanofi. PubChem has no record for it, so no formula, molecular weight or CAS number can be confirmed.
  • A Drugs@FDA substance-name query on 9 October 2026 returned no matching application.
  • The first-in-human results were published in Cell Metabolism (electronic publication 20 December 2021): in healthy subjects, single doses improved glycemic control during a mixed-meal tolerance test and were well tolerated.
  • The one registered human study, NCT04521738, enrolled 48 adults aged 18 to 55, started on 25 April 2019, completed on 26 September 2019 and has no posted results.
  • A ClinicalTrials.gov search returned exactly 1 record and the EU Clinical Trials Register returned 0 trials. SAR441255 does not appear on Sanofi's pipeline page updated 30 July 2026.
  • In the records reviewed, every weight-loss result for SAR441255 is from rodents or monkeys, and none reports weight loss in people.

What is SAR441255, and has anyone approved it?

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on exendin-4 and developed by Sanofi. It has never been approved. A Drugs@FDA query on 9 October 2026 returned no matching application, and PubChem has no record, so no formula, molecular weight or CAS number can be confirmed from an official database.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors. It is based on the exendin-4 sequence and was developed by Sanofi. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026, so there is no public formula, molecular weight or CAS number to cite from an official chemical database. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record. The amino acid sequence is not given in the sources reviewed.

An openFDA Drugs@FDA substance-name query for SAR441255 returned no matching application on 9 October 2026. The compound has never been approved. This is a US-scoped statement, and approvals outside the United States are not covered.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Drugs@FDA query, 9 October 2026: no matching application

Regulatory record

U.S. Food and Drug Administration. openFDA Drugs@FDA substance-name query for SAR441255, run on 9 October 2026.

An openFDA Drugs@FDA substance-name query for SAR441255 returned no matching application on 9 October 2026. The compound has never been approved.

Participants / model
Regulator database, not a population
Treatment
Exact substance-name search
Follow-up
Search run on 9 October 2026
Study design
FDA API query
Funding
not stated in the source

This is a US-scoped statement.

Read the original source

What did the first-in-human study find?

In healthy subjects, single subcutaneous doses of SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, and single doses were well tolerated. The published abstract gives no numbers, so this page carries no human Cmax, AUC, glucose or weight figure.

Bossart and colleagues, writing for the sponsor Sanofi, reported SAR441255 in Cell Metabolism (issue dated 4 January 2022, electronic publication 20 December 2021). The report states that SAR441255 displays high potency with balanced activation of all three target receptors. It also states that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated.

A commentary in the same issue summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans. The weight-lowering data are in monkeys. The human data are acute and glycemic.

The one registered human study, NCT04521738 (Sanofi study identifier TDU15478), was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses in lean to overweight adults. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. It started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28, and the secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted.

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study. Because the registry has no posted results and the report's abstract does not quantify the human findings, the only human information is the narrative statements above.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Commentary in the same issue: monkey weight loss, acute glucoregulatory effects in humans

Human study

Finan B et al. Cell Metab. 2022;34(1):3-4. PMID 34986336.

The commentary summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

Participants / model
Monkeys for weight; humans for glycemic endpoints
Treatment
Single doses
Follow-up
not stated in the source
Study design
Peer commentary on the primary report
Funding
not stated in the source

The weight-lowering data are in monkeys. The human data are acute and glycemic.

Read the original source
Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source

What do the animal studies show?

The sponsor's report states that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, and the commentary describes body weight lowering in monkeys. PET studies show receptor binding, including a 2025 pig study of GLP-1 and GIP receptor occupancy. In the records reviewed, every weight-loss result for SAR441255 is from rodents or monkeys.

The Cell Metabolism report states that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, and that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors. The commentary describes in vivo receptor occupancy and body weight lowering effects in monkeys. The animal part of the report used rodents and monkeys. The sources reviewed give no animal doses or weight numbers.

A 2025 study used PET with 68Ga-labelled exendin-4 and GIP tracers to measure GLP-1 receptor and GIP receptor occupancy by SAR441255 and by tirzepatide in pig pancreas and central nervous system, with in vitro binding assays on HEK293 cells overexpressing human GLP-1, GIP or glucagon receptors. Authors include Sanofi and academic groups. Continued use in pigs as a pharmacological tool is not continued clinical development.

A PubMed search for SAR441255 on 9 October 2026 returned 5 records. None reports weight loss in people, and in the records reviewed every weight-loss result for SAR441255 comes from rodents or monkeys. These are animal results and do not transfer to people.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Commentary in the same issue: monkey weight loss, acute glucoregulatory effects in humans

Human study

Finan B et al. Cell Metab. 2022;34(1):3-4. PMID 34986336.

The commentary summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

Participants / model
Monkeys for weight; humans for glycemic endpoints
Treatment
Single doses
Follow-up
not stated in the source
Study design
Peer commentary on the primary report
Funding
not stated in the source

The weight-lowering data are in monkeys. The human data are acute and glycemic.

Read the original source
2025 pig PET study: receptor occupancy by SAR441255 and tirzepatide, a research tool use

Animal study

Khalil A et al. EBioMedicine. 2025;122:106033. PMID 41274021.

A 2025 study used PET with 68Ga-labelled exendin-4 and GIP tracers to measure GLP-1 receptor and GIP receptor occupancy by SAR441255 and by tirzepatide in pig pancreas and central nervous system, with in vitro binding assays on HEK293 cells overexpressing human GLP-1, GIP or glucagon receptors. Authors include Sanofi and academic groups.

Participants / model
Healthy pigs and transfected human cell lines
Treatment
Intravenous tracer with SAR441255 or tirzepatide
Follow-up
not stated in the source
Study design
Preclinical PET and in vitro binding study
Funding
not stated in the source

Continued use in pigs as a pharmacological tool is not continued clinical development.

Read the original source
PubMed search, 9 October 2026: 5 records, none with human weight or diabetes results

PubMed search record

PubMed search run on 9 October 2026: SAR441255, 5 records.

A PubMed search for SAR441255 returned 5 records: the primary report, the accompanying commentary, a Japanese review of triagonists, a formulation stability modeling paper, and the 2025 PET study. None reports weight loss in people, none reports a multiple-dose human study, and none reports an HbA1c result in people with diabetes. In the records reviewed, every weight-loss result for SAR441255 comes from rodents or monkeys.

Participants / model
Records returned, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what the database returned on that date. It is not proof that no unindexed study exists.

Read the original source

Was SAR441255 shelved before its data were published?

No. The sponsor published the first-in-human results in Cell Metabolism on 20 December 2021, with a commentary in the same issue. The program did stop there, though: one registered trial completed on 26 September 2019 with no posted results, and SAR441255 is absent from Sanofi's pipeline page updated 30 July 2026.

Sellers describe SAR441255 as the balanced triagonist that was shelved before its data was published. The balanced part has support: the sponsor's report states high potency with balanced activation of all three target receptors.

The claim is wrong on the point it makes most loudly. The human data were not withheld. The sponsor published the first-in-human results in Cell Metabolism, with electronic publication on 20 December 2021 and a commentary in the same issue, and the paper is indexed in PubMed.

What is true is that the program went no further. The data were published and the program then stopped: one registered trial completed on 26 September 2019 with no posted results, 0 trials in the EU register, and no appearance on Sanofi's pipeline page updated 30 July 2026. The reason it stopped is not stated in any record reviewed, so none is given here.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Commentary in the same issue: monkey weight loss, acute glucoregulatory effects in humans

Human study

Finan B et al. Cell Metab. 2022;34(1):3-4. PMID 34986336.

The commentary summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

Participants / model
Monkeys for weight; humans for glycemic endpoints
Treatment
Single doses
Follow-up
not stated in the source
Study design
Peer commentary on the primary report
Funding
not stated in the source

The weight-lowering data are in monkeys. The human data are acute and glycemic.

Read the original source
Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source
Sanofi pipeline page, read 9 October 2026: SAR441255 does not appear

Regulatory record

Sanofi. Our pipeline, company web page carrying the notice "Updated on July 30, 2026", read on 9 October 2026.

Sanofi's public pipeline page, read on 9 October 2026 and carrying the notice "Updated on July 30, 2026", lists phase 1 through phase 3 assets including 18 distinct SAR development codes. SAR441255 does not appear anywhere on that page. The compound is not in the sponsor's current pipeline.

Participants / model
Sponsor pipeline disclosure, not a population
Treatment
Not applicable
Follow-up
Page updated 30 July 2026; read 9 October 2026
Study design
Sponsor primary disclosure
Funding
not stated in the source

This is a reading of a company page on one date, not a company statement about why the program stopped.

Read the original source

What happened to the program after the first study?

One registered trial completed on 26 September 2019 with no posted results. A ClinicalTrials.gov search returned exactly 1 record and the EU Clinical Trials Register returned 0 trials, and SAR441255 does not appear on the Sanofi pipeline page updated 30 July 2026. The reason the program stopped is not stated in any record reviewed.

A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, the phase 1 study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Sanofi's public pipeline page, read on 9 October 2026 and carrying the notice "Updated on July 30, 2026", lists phase 1 through phase 3 assets including 18 distinct SAR development codes. SAR441255 does not appear anywhere on that page, so the compound is not in the sponsor's current pipeline. This is a reading of a company page on one date, not a company statement about why.

The reason the program stopped is not stated in any record reviewed.

Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source
Sanofi pipeline page, read 9 October 2026: SAR441255 does not appear

Regulatory record

Sanofi. Our pipeline, company web page carrying the notice "Updated on July 30, 2026", read on 9 October 2026.

Sanofi's public pipeline page, read on 9 October 2026 and carrying the notice "Updated on July 30, 2026", lists phase 1 through phase 3 assets including 18 distinct SAR development codes. SAR441255 does not appear anywhere on that page. The compound is not in the sponsor's current pipeline.

Participants / model
Sponsor pipeline disclosure, not a population
Treatment
Not applicable
Follow-up
Page updated 30 July 2026; read 9 October 2026
Study design
Sponsor primary disclosure
Funding
not stated in the source

This is a reading of a company page on one date, not a company statement about why the program stopped.

Read the original source

How does SAR441255 work, and what is known about its fate in the body?

SAR441255 activates the GLP-1, glucagon and GIP receptors, with high potency and balanced activation of all three in the sponsor's report. No half-life, Tmax, Cmax or AUC is published in the sources reviewed.

SAR441255 is a synthetic exendin-4-based agonist of the GLP-1, glucagon and GIP receptors. The sponsor's report states high potency with balanced activation of all three target receptors. In healthy subjects it affected biomarkers of glucagon and GIP receptor activation, and in preclinical PET imaging it bound GLP-1 and glucagon receptors. A 2025 pig study measured GLP-1 receptor and GIP receptor occupancy by SAR441255 and by tirzepatide.

The registry lists Cmax, AUC and tmax as secondary outcomes of the phase 1 study, but no results are posted and the published abstract gives no numeric values. The page therefore carries no half-life, Tmax, Cmax or AUC for SAR441255.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
2025 pig PET study: receptor occupancy by SAR441255 and tirzepatide, a research tool use

Animal study

Khalil A et al. EBioMedicine. 2025;122:106033. PMID 41274021.

A 2025 study used PET with 68Ga-labelled exendin-4 and GIP tracers to measure GLP-1 receptor and GIP receptor occupancy by SAR441255 and by tirzepatide in pig pancreas and central nervous system, with in vitro binding assays on HEK293 cells overexpressing human GLP-1, GIP or glucagon receptors. Authors include Sanofi and academic groups.

Participants / model
Healthy pigs and transfected human cell lines
Treatment
Intravenous tracer with SAR441255 or tirzepatide
Follow-up
not stated in the source
Study design
Preclinical PET and in vitro binding study
Funding
not stated in the source

Continued use in pigs as a pharmacological tool is not continued clinical development.

Read the original source
Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source

What safety information exists?

In healthy subjects, single doses were well tolerated, and the commentary describes an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics after single doses. There is no multiple-dose study, no posted adverse event results and no study in people with obesity or type 2 diabetes, so safety beyond single doses is unknown.

The sponsor's report states that single doses were well tolerated in healthy subjects. The commentary in the same issue describes an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

The registry record for the one human study lists adverse events from screening to day 28 as the primary outcome, but no results are posted, so no adverse event rates are available. There is no multiple-dose study and no registered trial in people with obesity or type 2 diabetes. Safety beyond single doses in healthy adults is therefore unknown.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Commentary in the same issue: monkey weight loss, acute glucoregulatory effects in humans

Human study

Finan B et al. Cell Metab. 2022;34(1):3-4. PMID 34986336.

The commentary summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

Participants / model
Monkeys for weight; humans for glycemic endpoints
Treatment
Single doses
Follow-up
not stated in the source
Study design
Peer commentary on the primary report
Funding
not stated in the source

The weight-lowering data are in monkeys. The human data are acute and glycemic.

Read the original source
Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source

Why does SAR441255 sit in C tier?

The pharmacology is documented, including an acute glycemic effect in healthy subjects after single doses, but there is no chronic dosing study in people, no human weight result and no registration beyond one 48-person phase 1. That is a plausible mechanism with one small human study.

The pharmacology is real and documented: balanced potency at all three receptors, receptor occupancy by PET in pigs, body weight reduction in monkeys, and an acute improvement in glycemic control during a mixed-meal tolerance test in healthy subjects after single subcutaneous doses.

What does not exist is any chronic dosing study in people, any weight result in people, any study in people with obesity or type 2 diabetes, or any registration beyond one 48-person phase 1. A plausible mechanism with one small human study is C.

The supplier framing is wrong on its main point, because the data were published. What is true is that the program went no further: one registered trial completed on 26 September 2019, 0 trials in the EU register, and no appearance on Sanofi's pipeline page updated 30 July 2026.

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Commentary in the same issue: monkey weight loss, acute glucoregulatory effects in humans

Human study

Finan B et al. Cell Metab. 2022;34(1):3-4. PMID 34986336.

The commentary summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

Participants / model
Monkeys for weight; humans for glycemic endpoints
Treatment
Single doses
Follow-up
not stated in the source
Study design
Peer commentary on the primary report
Funding
not stated in the source

The weight-lowering data are in monkeys. The human data are acute and glycemic.

Read the original source
Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source
2025 pig PET study: receptor occupancy by SAR441255 and tirzepatide, a research tool use

Animal study

Khalil A et al. EBioMedicine. 2025;122:106033. PMID 41274021.

A 2025 study used PET with 68Ga-labelled exendin-4 and GIP tracers to measure GLP-1 receptor and GIP receptor occupancy by SAR441255 and by tirzepatide in pig pancreas and central nervous system, with in vitro binding assays on HEK293 cells overexpressing human GLP-1, GIP or glucagon receptors. Authors include Sanofi and academic groups.

Participants / model
Healthy pigs and transfected human cell lines
Treatment
Intravenous tracer with SAR441255 or tirzepatide
Follow-up
not stated in the source
Study design
Preclinical PET and in vitro binding study
Funding
not stated in the source

Continued use in pigs as a pharmacological tool is not continued clinical development.

Read the original source
PubMed search, 9 October 2026: 5 records, none with human weight or diabetes results

PubMed search record

PubMed search run on 9 October 2026: SAR441255, 5 records.

A PubMed search for SAR441255 returned 5 records: the primary report, the accompanying commentary, a Japanese review of triagonists, a formulation stability modeling paper, and the 2025 PET study. None reports weight loss in people, none reports a multiple-dose human study, and none reports an HbA1c result in people with diabetes. In the records reviewed, every weight-loss result for SAR441255 comes from rodents or monkeys.

Participants / model
Records returned, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what the database returned on that date. It is not proof that no unindexed study exists.

Read the original source
Sanofi pipeline page, read 9 October 2026: SAR441255 does not appear

Regulatory record

Sanofi. Our pipeline, company web page carrying the notice "Updated on July 30, 2026", read on 9 October 2026.

Sanofi's public pipeline page, read on 9 October 2026 and carrying the notice "Updated on July 30, 2026", lists phase 1 through phase 3 assets including 18 distinct SAR development codes. SAR441255 does not appear anywhere on that page. The compound is not in the sponsor's current pipeline.

Participants / model
Sponsor pipeline disclosure, not a population
Treatment
Not applicable
Follow-up
Page updated 30 July 2026; read 9 October 2026
Study design
Sponsor primary disclosure
Funding
not stated in the source

This is a reading of a company page on one date, not a company statement about why the program stopped.

Read the original source

Studies and sources

Cell Metabolism report (Sanofi authors), December 2021: balanced triagonist, single doses in healthy subjects

Human study

Bossart M et al. Cell Metab. 2022;34(1):59-74.e10. PMID 34932984.

SAR441255 is a synthetic peptide agonist of the GLP-1, glucagon and GIP receptors, based on the exendin-4 sequence and developed by Sanofi. Bossart and colleagues reported it in Cell Metabolism, issue dated 4 January 2022 with electronic publication on 20 December 2021. The report states that SAR441255 displays high potency with balanced activation of all three target receptors, that in animal models metabolic outcomes were superior to a dual GLP-1 and glucagon receptor agonist, that preclinical PET imaging demonstrated binding to GLP-1 and glucagon receptors, and that in healthy subjects SAR441255 improved glycemic control during a mixed-meal tolerance test and affected biomarkers of glucagon and GIP receptor activation, with single doses well tolerated. PubChem compound and substance lookups for SAR441255 returned no record on 9 October 2026.

Participants / model
Healthy subjects for the clinical part; rodents and monkeys for the animal part
Treatment
Single subcutaneous doses in humans
Follow-up
not stated in the source
Study design
Original research report by the sponsor covering preclinical pharmacology and a first-in-human study
Funding
not stated in the source

The abstract does not quantify the human results, so no human Cmax, AUC, glucose or weight figure is given. Anything a vendor prints as a CAS number or molecular weight for SAR441255 cannot be matched to a PubChem record.

Read the original source
Commentary in the same issue: monkey weight loss, acute glucoregulatory effects in humans

Human study

Finan B et al. Cell Metab. 2022;34(1):3-4. PMID 34986336.

The commentary summarizes the report as giving in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results, with positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics following single doses to humans.

Participants / model
Monkeys for weight; humans for glycemic endpoints
Treatment
Single doses
Follow-up
not stated in the source
Study design
Peer commentary on the primary report
Funding
not stated in the source

The weight-lowering data are in monkeys. The human data are acute and glycemic.

Read the original source
Registry NCT04521738: phase 1, 48 adults, completed 26 September 2019, no posted results

Trial registry record

ClinicalTrials.gov. NCT04521738, randomized double-blind placebo-controlled single ascending dose study of SAR441255 (Sanofi study identifier TDU15478).

NCT04521738 was a randomized, double-blind, placebo-controlled study of single ascending subcutaneous doses of SAR441255 in lean to overweight adults, sponsor Sanofi, study identifier TDU15478. Actual enrollment was 48, with participants aged 18 to 55, BMI 20 to 30 kg/m2, body weight 65 to 90 kg, fasting plasma glucose under 126 mg/dL and HbA1c under 6.5%. The study started on 25 April 2019 and completed on 26 September 2019. The primary outcome was the number of participants with adverse events from screening to day 28; secondary outcomes were Cmax, AUC, tmax and glucose, insulin and C-peptide profiles. No results are posted. A ClinicalTrials.gov term search for SAR441255 returned exactly 1 record on 9 October 2026, this study. A search of the EU Clinical Trials Register on the same date returned 0 trials with a EudraCT protocol. There is no phase 2 or later study registered in either registry.

Participants / model
48 lean to overweight adults aged 18 to 55
Treatment
Single ascending subcutaneous doses, solution for injection
Follow-up
25 April 2019 to 26 September 2019; adverse events followed to day 28
Study design
Randomized double-blind placebo-controlled single ascending dose study; no posted results
Funding
not stated in the source

There is no registered trial of SAR441255 in people with obesity or type 2 diabetes, and no multiple-dose study.

Read the original source
Sanofi pipeline page, read 9 October 2026: SAR441255 does not appear

Regulatory record

Sanofi. Our pipeline, company web page carrying the notice "Updated on July 30, 2026", read on 9 October 2026.

Sanofi's public pipeline page, read on 9 October 2026 and carrying the notice "Updated on July 30, 2026", lists phase 1 through phase 3 assets including 18 distinct SAR development codes. SAR441255 does not appear anywhere on that page. The compound is not in the sponsor's current pipeline.

Participants / model
Sponsor pipeline disclosure, not a population
Treatment
Not applicable
Follow-up
Page updated 30 July 2026; read 9 October 2026
Study design
Sponsor primary disclosure
Funding
not stated in the source

This is a reading of a company page on one date, not a company statement about why the program stopped.

Read the original source
2025 pig PET study: receptor occupancy by SAR441255 and tirzepatide, a research tool use

Animal study

Khalil A et al. EBioMedicine. 2025;122:106033. PMID 41274021.

A 2025 study used PET with 68Ga-labelled exendin-4 and GIP tracers to measure GLP-1 receptor and GIP receptor occupancy by SAR441255 and by tirzepatide in pig pancreas and central nervous system, with in vitro binding assays on HEK293 cells overexpressing human GLP-1, GIP or glucagon receptors. Authors include Sanofi and academic groups.

Participants / model
Healthy pigs and transfected human cell lines
Treatment
Intravenous tracer with SAR441255 or tirzepatide
Follow-up
not stated in the source
Study design
Preclinical PET and in vitro binding study
Funding
not stated in the source

Continued use in pigs as a pharmacological tool is not continued clinical development.

Read the original source

Why is SAR441255 in C tier?

C fits a plausible mechanism with one small human study. The pharmacology is documented, including an acute glycemic effect in healthy subjects after single doses, but there is no chronic dosing study, no human weight result and no registered trial beyond one 48-person phase 1. The sellers' claim that the data were never published is wrong: they were published in 2021.