When Will ENDO-205 Be Available? The Endometriosis Peptide Timeline

If you have endometriosis, you have probably already lived the usual script: years of pain before anyone gave it a name, then a choice between hormones that flatten you and surgery that may need repeating. So when a headline says a peptide can make endometriosis lesions disappear without hormones, you want to know one thing. When can I get it?

Here is what ENDO-205 is, what has and has not been shown, why anything sold online as ENDO-205 cannot be trusted, the realistic timeline, and what you can do in the meantime, including the bloodwork that is useful while you wait.

What ENDO-205 is

ENDO-205 is the lead drug from EndoCyclic Therapeutics, a US company founded by Tanya Petrossian, who has stage IV endometriosis herself (Drug Discovery News, 2026). The company describes it as "a first-in-class, non-hormonal targeted peptide therapeutic for endometriosis" (EndoCyclic, 2026).

The company says the peptide is taken up through "a specific endocytic pathway that is exclusively active in diseased tissue" and that, once inside the cell, "the peptides activate in response to local pH" (EndoCyclic). Drug Discovery News describes the result as programmed cell death, after which the immune system clears the debris (Drug Discovery News, 2026). If that works in people, it would be the first treatment aimed at removing lesions without suppressing your hormones or cutting them out.

Two details circulating online are not from the company. Some peptide-vendor sites describe a Wnt/beta-catenin mechanism and a specific activation pH. Neither appears in EndoCyclic's own materials or its NIH grant abstracts, which describe the target only as "a downstream component of a pathway known to contribute to endometriosis pathogenesis" (NIH RePORTER). Treat those details as unverified.

Is ENDO-205 hormonal?

No. Current medical treatments for endometriosis work by lowering or overriding estrogen, which is why they cause hot flushes, bleeding changes or bone loss. ENDO-205 is designed to act on the lesion cells directly. In animal work funded by the NIH, the company reports lesion regression "without inducing toxicity or alterations in estrous cyclicity", meaning the animals' reproductive cycles kept running normally (NIH RePORTER).

Does it work for adenomyosis?

Nobody knows. Adenomyosis is closely related: it is endometrium-like tissue growing inside the muscle wall of the uterus rather than outside it, and the two conditions share much of their biology (Bulun et al., 2023). EndoCyclic has only described ENDO-205 for endometriosis.

What has actually been proven

Here is the full evidence base, and it is short.

• Animal studies. The company reports that "in preclinical studies, ENDO-205 demonstrated elimination of endometriosis lesions and associated inflammation, with no safety signals observed in GLP toxicology studies" (EndoCyclic, 2026). The NIH grant abstracts describe in vivo studies without naming the species, and no dose or effect size has been published.
• No peer-reviewed papers. We searched PubMed and could not find a single published study of ENDO-205. Everything above is company-reported.
• NIH funding. The NIH's child health institute has funded the program since 2019 through small-business grants totalling roughly $9.7 million across nine awards from 2019 to 2026 on the NIH's public database, under the company's former name, Endomet Biosciences (NIH RePORTER). The company says its 2025 grant earned a "perfect overall impact score of 10" (EndoCyclic, 2025). That is a strong signal that reviewers rated the science and plan highly. It is not evidence the drug works in women.
• FDA clearance to start testing. On 23 March 2026 the FDA cleared the company's IND. That means the FDA allowed the company to start giving the drug to people in a trial. It is not an approval.

The CEO has said that in preclinical work "continued dosing may not be required" once the process starts (Drug Discovery News, 2026), and an NIH showcase page says a course "lasting up to 3 months, is expected to clear all lesions" (NIH SEED). Both are company expectations from preclinical work. Neither has been tested in a single woman.

How is ENDO-205 given?

It will be tested as an injection, according to the CEO in a June 2026 interview, who also mentioned data suggesting a pill form might be possible later (Daily Bruin, 2026). No dose or schedule is public.

When will ENDO-205 be available? The realistic timeline

Drug development runs in stages, and each one has to succeed before the next starts.

The participant numbers come from the FDA (FDA); the averages come from a large industry analysis of drug programs between 2011 and 2020, which found the average time from phase 1 to approval was 10.5 years (BIO, Informa and QLS, 2021).

Most drugs never finish. In that same analysis, only 7.9% of drugs entering phase 1 were eventually approved. For peptides specifically it was 8.0%:

A more generous academic estimate, which tracks each drug's full path rather than phase-by-phase averages, puts the overall chance at 13.8% and about 20% for metabolic and endocrine drugs (Wong et al., 2019). Neither analysis has a separate women's health category, so these are the best available proxies.

Put together: if ENDO-205's phase 1 starts in 2027, the average drug would reach approval around 2037. Programs can move faster, especially with FDA fast-track or breakthrough designations, and ENDO-205 has not announced either. A realistic expectation is "years away, and not guaranteed", not "next year".

Why is the first trial in healthy women?

Because phase 1 is about safety and dose, not about whether it works. Testing first in healthy volunteers is standard for drugs that are not expected to be dangerous, since it isolates the drug's own side effects from those of the disease (FDA). EndoCyclic says its first study will be "in healthy pre-menopausal women of reproductive age" (EndoCyclic, 2026). Women with endometriosis would be expected to join from phase 2.

Is ENDO-205 for sale? Why any vial you find isn't real

Search "ENDO-205 peptide for sale" and you are looking for something that does not exist. We found no listing for it in early October 2026, and one research-peptide vendor that wrote about it says plainly that it is not available to buy. As the name spreads, that will change. Here is why any vial that appears cannot be trusted.

Nobody outside the company knows what the molecule is. EndoCyclic has never published ENDO-205's sequence. To make it, a seller would need to know exactly which amino acids, in what order, cyclised how. Anything labelled "ENDO-205" is therefore a guess at best and a relabelled cheaper peptide at worst.

A certificate of analysis cannot prove identity here. A typical certificate shows an HPLC purity peak and sometimes a mass. Purity tells you the sample is mostly one compound, not which compound. A mass can only be checked against a reference that nobody outside EndoCyclic has. A seller can show a clean, professional-looking certificate for a peptide that is not ENDO-205 at all. This is our reasoning rather than a published finding, but it follows directly from how those tests work.

Online peptides already fail basic quality tests. When researchers bought semaglutide sold online without a prescription, all three vials that arrived were judged probably substandard or falsified: purity measured 7.7% to 14.4% against a claimed 99%, every sample contained bacterial endotoxin, and none of the three prefilled pens ordered ever arrived (Ashraf et al., 2024). That is semaglutide, a drug with a published structure and a legitimate reference standard. Even legitimate custom peptides can hide surprises: in one analysis, two commercially sourced custom peptides contained undeclared mannitol at 20% and 43% of their weight, which liquid-chromatography quality testing is blind to (Choules et al., 2020). An unpublished molecule is harder, not easier, to sell honestly.

We covered how people test grey-market vials, and the limits of those tests, in our guide to heavy metals and purity in UGL steroids and peptides.

Can you get ENDO-205 in Australia, Canada or the UK?

Not today. Every legal route to an unapproved drug depends on the manufacturer agreeing to supply it, and none of them can force that.

• Australia. The TGA's Special Access Scheme and Authorised Prescriber pathway let doctors access unapproved medicines, but the TGA states that "sponsors are under no obligation to supply an unapproved therapeutic good" (TGA) and that the scheme "is reliant on the sponsor being able to supply the product in Australia and this is likely to depend on its stage of development" (TGA). The Personal Importation Scheme requires a valid Australian prescription, and lets you import a medicine that exists somewhere to be bought. ENDO-205 is sold nowhere. The TGA also notes counterfeit medicines are prohibited from import even if you did not know they were fake (TGA).
• United States. FDA expanded access (compassionate use) is limited to serious or immediately life-threatening conditions, and in practice needs the manufacturer to agree to supply the drug (FDA; FDA). The Right to Try law only applies to drugs that have completed phase 1, and even then "does not require a sponsor to provide" it (FDA). Right to Try is also limited to life-threatening conditions.
• Canada. Health Canada's Special Access Programme states that it "cannot compel a manufacturer" to supply an unauthorised drug (Health Canada).
• UK. The Early Access to Medicines Scheme is applied for by companies, not patients, and is used late in development (MHRA).

How to get into an ENDO-205 clinical trial

The route to ENDO-205 is a trial, and the first one will not include women with endometriosis. To be ready for the later ones:

• Watch ClinicalTrials.gov. Search for "EndoCyclic" as the sponsor rather than just "ENDO-205". A plain keyword search for ENDO-205 currently returns an unrelated hyponatraemia study whose internal code happens to be "Endo205".
• Watch the Australian New Zealand Clinical Trials Registry (anzctr.org.au) if you are in Australia. Trials only appear there if they run sites in Australia or New Zealand.
• Follow EndoCyclic's news page, where trial starts are announced.
• Ask your specialist to keep you in mind. Endometriosis clinics are often approached when trials recruit.

What you can do while you wait

ENDO-205 may change treatment one day. Effective treatment exists now, and the biggest problem for most women is still getting to it.

Get diagnosed sooner. Endometriosis affects roughly 1 in 10 women of reproductive age (WHO). In an Australian survey, women waited an average of 8 years for a diagnosis, although the delay is shrinking for women presenting more recently (Armour et al., 2020). The European guideline challenges laparoscopy as the only route to diagnosis (Becker et al., 2022): specialist imaging can identify many cases, so ask about it. Keep a symptom diary of pain, bleeding and bowel or bladder symptoms against your cycle. It shortens the conversation.

Medical options with real trial data.

• Dienogest, a progestogen, reduced pelvic pain significantly more than placebo over 12 weeks in a randomised trial (Strowitzki et al., 2010), and the benefit held in a year-long extension (Petraglia et al., 2012).
• Oral GnRH antagonists: with relugolix combination therapy, 75% of women had a meaningful reduction in period pain against 27% to 30% on placebo in two phase 3 trials (Giudice et al., 2022). Elagolix showed similar results (Taylor et al., 2017). The cost is lower estrogen, which affects bone density and lipids, which is why add-back hormones are used and bone health is monitored.
• Combined hormonal contraception, the hormonal IUD and surgery remain standard options. Your specialist will weigh them against your symptoms and fertility plans.

None of these remove the disease the way ENDO-205 hopes to. They are what works today, and they are worth starting rather than waiting a decade.

Bloodwork worth tracking while you wait

No blood test can diagnose or rule out endometriosis. A Cochrane review of 122 blood markers across 141 studies found none accurate enough for clinical use (Nisenblat et al., 2016). Bloodwork is still useful, for tracking what endometriosis and its treatment do to you.

What if my CA-125 is high, or normal?

CA-125 is the marker people ask about most. At 30 U/mL or above it was 93% specific for endometriosis, but it only caught 52% of cases, and just 24% of minimal disease (Hirsch et al., 2016). A raised result supports the diagnosis, and a normal result does not rule it out. CA-125 also rises during periods and with other conditions, so don't read too much into it as a progress tracker.

Iron: the marker most likely to change how you feel

Iron deficiency is common and often missed. In women with endometriosis attending two specialist centres, 53% were iron deficient and 14% had iron-deficiency anaemia. Even among women who did not report heavy periods, 47% were iron deficient, and iron deficiency tracked with worse fatigue (Goldberg et al., 2025). That study used ferritin below 30 as its cut-off, and found that adding transferrin saturation caught more cases than ferritin alone. Track ferritin, transferrin saturation and haemoglobin together. If you are exhausted and your doctor has only checked haemoglobin, ask for the other two.

AMH if fertility matters to you

AMH reflects ovarian reserve, not endometriosis itself. It matters because surgery on ovarian endometriomas lowers it: across eight studies, AMH fell by an average of about 1.1 ng/mL after cyst removal (Raffi et al., 2012). A baseline AMH before any ovarian surgery gives you and your fertility specialist a reference point. Our Hashimoto's and miscarriage guide covers other bloodwork worth having before trying to conceive.

Markers on hormonal treatment

If you are on a GnRH antagonist, the trials flagged rising lipids and falling bone density (Taylor et al., 2017), so ask your prescriber about a lipid panel and bone density monitoring. CRP and thyroid antibodies come up often in endometriosis forums. Neither diagnoses endometriosis, and the link with thyroid autoimmunity rests on generally poor-quality evidence (Shigesi et al., 2019), so they are worth checking for their own reasons rather than as endometriosis markers.

Frequently asked questions

Is ENDO-205 FDA approved?

No. The FDA cleared its Investigational New Drug application in March 2026, which allows human trials to begin. Approval would require successful phase 1, 2 and 3 trials and a separate application.

What are the side effects of ENDO-205?

Unknown in humans. The company reports no safety signals in animal toxicology studies. Phase 1 exists to find out what side effects occur in people.

How much will ENDO-205 cost?

There is no price, because there is no product. Any price you see attached to "ENDO-205" belongs to something else.

Is ENDO-205 a cure for endometriosis?

It is designed to eliminate lesions rather than suppress symptoms, which is why it is being called potentially disease-modifying. Whether it does that in women, and whether lesions stay gone, will only be known after trials.

Key takeaways

• ENDO-205 is a non-hormonal peptide designed to destroy endometriosis lesions. All evidence so far is company-reported animal data, with no published studies
• FDA clearance in March 2026 only allows human testing. The first trial is planned in healthy women and no registration was publicly visible as of October 2026
• On industry averages, drugs take about 10.5 years from phase 1 to approval, and fewer than 1 in 10 succeed. Expect years, not months
• Anything sold online as ENDO-205 cannot be verified, because its sequence has never been published
• No legal access route exists in Australia, the US, Canada or the UK without the company agreeing to supply
• Effective treatments exist now. Push for diagnosis, and track ferritin, transferrin saturation and haemoglobin, since iron deficiency affects about half of women with endometriosis

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References

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