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safety record

Fosgonimeton: what has been measured about safety

The safety record for fosgonimeton, read as a record: which studies were designed to answer a safety question, which of them reported, and what the one posted adverse event table holds and cannot settle.

Last Reviewed Editorial policy Methodology

Fosgonimeton is the compound on this site whose safety questions were put to the right studies. A Phase 1 in 88 participants was run specifically for safety, tolerability and pharmacokinetics [4]. An open-label extension in 423 participants listed the incidence of treatment-emergent adverse events as its own primary outcome and posted its results to the registry [2]. A separate Phase 1 in 8 participants characterised absorption, metabolism and excretion [6].

Three of the six registered trials completed without posting results: the smaller Phase 2 [3] and both Phase 1 studies [4] [6]. So some figures exist somewhere and are not on the public record, which is a different situation from a compound whose studies were never run, and this page keeps the two apart rather than collapsing both into the same sentence. What is public is the open-label extension's adverse event table, reported below as the registry structures it: group totals, the six non-serious terms that clear its 4 per cent reporting threshold, and the count rather than the list of its 58 distinct serious terms [2].

What can be read directly is the shape of the exposure: 554 participants to a primary endpoint at 26 weeks in the pivotal trial [1], an extension that was stopped for a reason the registry ties to that endpoint rather than to a safety finding [2], and a second Phase 2 terminated at 28 participants for study design [5].

Not medical advice

This page reports what has been documented about a compound. It is not medical advice, not a diagnosis, not a dosing protocol, and not a recommendation to obtain or use anything described here. Talk to a licensed clinician about anything concerning your health. Read the full disclaimer.

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What this page reports, and what it does not

We report what has been documented. We do not prescribe what should be done.

Every sentence below reports what a named source measured or recorded, in what system, and what it found. Where the answer is that a study exists and has not reported, the page says which study and what it was built to measure.

This page publishes no dose, no schedule, no route instruction and no list of people who should avoid anything. A list of who should not use a compound is a directions-for-use document, and it only makes sense if the reader is going to use the thing. What replaces it is a description of the compound and its record, written about the molecule rather than about the reader.

One thing separates this compound from most of the catalogue and it is worth fixing before the first section. It is an investigational medicine given by injection under supervision, not a research chemical, and this site is not aware of any consumer supply. Anything sold under this name is not the material any trial below used.

What has been measured

The studies designed to answer a safety question

Two records in this programme exist to answer a safety question rather than an efficacy one. The Phase 1 in 88 participants is registered as a safety, tolerability and pharmacokinetics study, which is the study type built to find the boundaries of an exposure before anyone is treated for benefit [4]. The open-label extension in 423 participants carries the incidence of treatment-emergent adverse events as its own primary outcome, which means adverse events were the thing it was counting rather than a secondary observation [2].

The Phase 1 has posted no results. The extension has, and it was terminated for a reason the registry states plainly and which is not a safety reason: the parent trial did not meet its primary endpoint [2]. A trial stopped because the drug did not work and a trial stopped because the drug did something unwanted are different events, and the registry's own field distinguishes them here.

How far the human exposure reaches

The pivotal Phase 2/3 enrolled 554 participants with mild to moderate Alzheimer's disease and ran to a primary endpoint at 26 weeks [1]. That is the largest exposure to this compound on the public record.

It is not the longest. The open-label extension followed 423 participants for up to 173 weeks before the study was terminated, short of its protocolled 206 weeks, and 173 is the ceiling of that follow-up rather than its typical length: 35 of the 423 completed, and 224 stopped at the early termination [2]. So some participants were followed for years, in a single arm with no comparator, and the adverse event table below is what that produced. Exposure in the remaining trials ran to weeks and months: 88 participants in the Phase 1 [4], 77 in the smaller Phase 2 [3], 28 in the terminated Parkinson's and Lewy body study [5], and 8 in the single-dose absorption study [6].

The population matters as much as the duration. Every participant in the programme had a diagnosis and was treated under a protocol, in a supervised setting, with monitoring and withdrawal criteria attached. Nothing on this record describes exposure outside those conditions.

What the two terminations say, in the registry's own words

Two records in this programme are marked terminated and their stated reasons are different from each other, so neither should be read as the other. The extension's field reads that the study was terminated after the Phase 2/3 parent trial did not meet its primary endpoint [2]. The Parkinson's disease dementia and Lewy body study's field reads that enrollment ended early due to study design limitations, which is the sponsor's own wording [5].

Neither reason is a safety reason, and this page does not supply one. A registry field recording why a trial stopped is a primary source, and the useful thing about a primary source is that it can be quoted rather than interpreted. Where a field is empty, the honest report is that it is empty; where it is filled, the honest report is what it says.

The one posted adverse event table, and what a single arm can show

The open-label extension posted an adverse event table, and it is the only one in this programme. Across its 423 participants, in a single arm all receiving the drug, the registry records 4 deaths, 54 participants with at least one serious adverse event across 58 distinct serious terms, and 348 participants with at least one non-serious event. Participants were followed up to 173 weeks, and the registry notes that the protocolled 206-week treatment duration ended early because the study was terminated [2].

The non-serious side is listed at a 4 per cent reporting threshold, which leaves six terms, and six is small enough to give whole. Injection site reactions in 213 of 423, COVID-19 in 44, urinary tract infection in 28, a fall in 24, eosinophilia in 20, and upper respiratory tract infection in 19 [2]. The first of those is the one a reader should stop on: at roughly half the arm it is far the largest figure in the table, and it is the one most obviously attributable to the drug rather than to the population, because the drug is an injection and the others are not. The registry also records that 50 of the 423 discontinued for an adverse event [2].

Everything below the 4 per cent threshold is absent from the non-serious list by the registry's own reporting rule, so that list is complete above the threshold and not complete overall. The 58 serious terms are not reproduced here one by one; the categories they fall into are named in the next paragraph.

Read the shape of that before the size of it. A single-arm open-label extension has no comparator, so nothing in the table separates the drug from the disease, from the age of the population, or from time. The serious terms posted include falls, fractures, infections, seizures and cancers [2]. What the background rate for any of those would be in an untreated group of the same age and diagnosis is not something this trial measured and not something this page asserts. A count from one arm answers how often something was recorded, never whether the drug caused it, and that cuts in both directions rather than only the reassuring one.

The study that would have supplied the comparison is the Phase 1 built for safety and tolerability in 88 participants, and it has posted nothing [4]. So the controlled half of this compound's safety record is the half that is not public, and the uncontrolled half is the one a reader can read. [Human open-label] [2]

What has not been characterised

Set out plainly, so the shape of the gap is visible rather than implied. Long-term exposure has been observed and not characterised, which are different things. The extension followed 423 participants for up to 173 weeks, with 35 completing and 224 stopping at the early termination, and posted an adverse event table from that single arm with nothing to compare it against [2]. The controlled record stops much earlier, at the pivotal trial's 26-week primary endpoint [1]. So what a year or three of this compound does relative to not taking it is unaddressed, and nothing describes exposure outside a supervised trial in a diagnosed population.

Three completed trials have posted nothing: the smaller Phase 2 [3] and both Phase 1 studies [4] [6]. Two of those three are the studies built to answer a safety question, so the controlled adverse event comparison this compound should have is the part that is missing, while the uncontrolled single-arm table is the part that is public [2]. What the three found is unknown rather than negative, and those two words are not interchangeable. This site did not locate a peer-reviewed paper reporting the Phase 2/3 either, and did not search for one, which is recorded here rather than glossed.

Nothing is published on what is in anything sold under this name. The trial material was a manufactured investigational medicine with a regulatory file behind it, and this site is not aware of a legitimate consumer supply, so a product offered under this name has no relationship to the exposures described above.

Our takeThe instructive thing about this record is what it separates. Most compounds on this site have no safety data because nobody ran the studies. Here the studies were run, by a sponsor, under protocol, and two of the three that would answer a safety question have simply not reported. Unrun and unreported look identical from outside and are not the same failure, and only one of them can be fixed by someone posting a file.

Talk to a licensed clinician about anything concerning your health.

Frequently asked questions

Is fosgonimeton safe?

This site takes no position on that for any compound, and the published record could not settle it here in any case. The Phase 1 built to answer the question in 88 participants has posted no results [4], and the extension that counted adverse events as its own primary outcome was stopped after the parent trial missed its endpoint [2]. What is established is the shape of the exposure: 554 participants to a 26-week endpoint in the pivotal trial, which is the controlled part [1], and 423 participants followed up to 173 weeks in the extension, which is a single arm with nothing to compare it against and is where the one posted adverse event table comes from [2].

What side effects were reported?

One table is public, and it belongs to the open-label extension: across 423 participants in a single arm, the registry records 4 deaths, 54 participants with at least one serious adverse event across 58 distinct serious terms, and 348 with at least one non-serious event, over a timeframe of up to 173 weeks [2]. A single arm has no comparator, so none of that separates the drug from a population with Alzheimer's disease followed for that long. The Phase 1 built to measure tolerability has posted nothing [4], so the controlled comparison is not public.

Were any of the trials stopped for safety?

Neither of the two terminated records gives a safety reason. The extension's registry field states that it was terminated after the Phase 2/3 parent trial did not meet its primary endpoint [2]. The Parkinson's disease dementia and Lewy body study's field states that enrollment ended early due to study design limitations [5]. Those are the registry's own words, and this page does not supply a reason neither field gives.

Does fosgonimeton affect the liver or the kidneys?

No trial reports either as a measured laboratory outcome. Chemistry of that kind sits in trial results, and three of the six trials have posted none at all [3] [4] [6]. What the extension posted is an adverse event table rather than laboratory values, and it does carry three terms in those organ systems, each in 1 of 423: cholecystitis, ureterolithiasis and clear cell renal cell carcinoma, alongside urinary tract infection as a serious event in 4 of 423 [2]. Those are diagnoses recorded in a single arm with no comparator, in a population followed up to 173 weeks, so they establish nothing about cause. The point that stands is the narrower one: no liver or kidney chemistry was published, in either direction.

Has long-term use been characterised?

Only in one arm, with nothing to compare it against. The open-label extension followed 423 participants for up to 173 weeks before being terminated short of its protocolled 206, with 35 completing and 224 stopping at the termination, and its adverse event table is the record of that [2]. The controlled exposure stops much earlier, at the pivotal trial's 26-week primary endpoint in 554 participants [1], and the Phase 1 built to measure tolerability has posted nothing [4]. So some participants were followed for years and none of that follow-up is controlled.

Does this compound's record say anything about dihexa?

Not as evidence about that compound. They are different molecules aimed at the same hepatocyte growth factor and c-Met system, and human exposure to one is not human exposure to the other. What dihexa's own record holds, which is an FDA statement that no human exposure data exists for it by any route, is set out on its safety record linked at the foot of this page.

References

  1. LeonaBio. ATH-1017 for Treatment of Mild to Moderate Alzheimer's Disease (LIFT-AD). Phase 2/3, 554 participants, completed 15 July 2024. Results posted. Primary outcome the Global Statistical Test score at week 26; primary analysis population placebo or 40 mg, modified intention-to-treat, restricted to participants not taking acetylcholinesterase inhibitors. Posted least-squares means: placebo -0.126 (SE 0.0683, n=144), ATH-1017 40 mg -0.208 (SE 0.0707, n=143). No analysis or p-value posted for the primary outcome. Read through the v2 API on 23 August 2026. ClinicalTrials.gov. 2020. NCT04488419
  2. LeonaBio. Open Label Study of ATH-1017 for Treatment of Mild to Moderate Alzheimer's Disease. Phase 2/3, 423 participants, terminated, completed 23 October 2024. Results posted. The registry's whyStopped field reads: ATH-1017-AD-0203 was terminated after the Ph2/3 parent trial (LIFT-AD; NCT04488419) did not meet its primary endpoint, the GST score. ClinicalTrials.gov. 2021. NCT04886063
  3. LeonaBio. A Study of ATH-1017 in Mild to Moderate Alzheimer's Disease. Phase 2, 77 participants, completed. No posted results. ClinicalTrials.gov. 2020. NCT04491006
  4. LeonaBio. Safety, Tolerability, and Pharmacokinetics Study of ATH-1017. Phase 1, 88 participants, completed. No posted results. ClinicalTrials.gov. 2017. NCT03298672
  5. LeonaBio. ATH-1017 Treatment in Subjects With Parkinson's Disease Dementia or Dementia With Lewy Bodies (SHAPE Trial). Phase 2, 28 participants, terminated, completed 19 April 2023. The registry's whyStopped field reads: Enrollment ended early due to study design limitations. ClinicalTrials.gov. 2021. NCT04831281
  6. LeonaBio. A Study of the Absorption, Metabolism, and Excretion of ATH-1017. Phase 1, 8 participants, completed. No posted results. ClinicalTrials.gov. 2022. NCT05511558
  7. ClinicalTrials.gov. Registry sweep for fosgonimeton, ATH-1017, NDX-1017 and fosgonimeton acetate across the intervention and free-text fields, run through the v2 API on 23 August 2026. Six distinct records returned, all of them this compound. ClinicalTrials.gov. 2026. ClinicalTrials.gov
  8. Wright JW, Harding JW. The Brain Hepatocyte Growth Factor/c-Met Receptor System: A New Target for the Treatment of Alzheimer's Disease. J Alzheimers Dis. 2015. PMID 25649658
  9. Wright JW, Kawas LH, Harding JW. The development of small molecule angiotensin IV analogs to treat Alzheimer's and Parkinson's diseases. Prog Neurobiol. 2015. PMID 25455861
  10. Ho JK, Nation DA. Cognitive benefits of angiotensin IV and angiotensin-(1-7): A systematic review of experimental studies. Neurosci Biobehav Rev. 2018. PMID 29733881
  11. Benoist CC, Kawas LH, Zhu M, Tyson KA, Stillmaker L, Appleyard SM, Wright JW, Wayman GA, Harding JW. The procognitive and synaptogenic effects of angiotensin IV-derived peptides are dependent on activation of the hepatocyte growth factor/c-met system. J Pharmacol Exp Ther. 2014. PMID 25187433 DOI 10.1124/jpet.114.218735 Retracted April 2025. Cited here only to identify the mechanism literature shared with the research chemical sold on this target, and not as evidence.
  12. Siller R, Greenhough S, Naumovska E, Sullivan GJ. Small-molecule-driven hepatocyte differentiation of human pluripotent stem cells. Stem Cell Reports. 2015. PMID 25937370