ENDO-205_Dosage, benefits & legal status
Also known as ENDO205
An experimental non-hormonal peptide for endometriosis with an FDA-cleared IND and no human data yet.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is ENDO-205?
Plain language first. The technical label stays, but it never stands alone.Overview
The aim is to remove lesions rather than suppress hormones the way elagolix or relugolix do. The FDA cleared its IND in March 2026 for a first trial in healthy women, but no trial registration or dosing announcement had appeared by October 2026. Its structure and target are undisclosed.
ENDO-205 is a peptide from EndoCyclic Therapeutics of Irvine, California (legally Endomet Biosciences), founded by Tanya Petrossian. The company says it enters diseased tissue through a specific uptake pathway and is activated by local pH to clear endometriosis lesions.
What it's used for
An experimental peptide meant to clear endometriosis lesions without hormones. Mouse results only; the first human trial has not visibly started.
How does ENDO-205 work?
What it does in the body, and where.EndoCyclic has not disclosed ENDO-205's structure or target, so what follows is the company's own account.
- 01UptakeThe company says the peptide enters cells through an endocytic pathway that is active only in diseased tissue.
- 02ActivationOnce inside, it is said to switch on in response to local pH and bind an intracellular target, changing its shape to suppress harmful signalling. NIH grant abstracts describe inhibiting a downstream part of a pathway that contributes to endometriosis.
- 03Lesion clearanceGrant reports describe lesion regression in mice, with more cell death and less cell division. Trade press says the immune system then clears the debris. None of this has been tested in people.
- 04A possible targetThe company's patent family covers cyclic peptides that bind beta-catenin and block Wnt signalling, but no document links ENDO-205 to that patent.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Animal results
Early research- Animal studyNIH grant reports describe endometriosis lesions regressing and disappearing in mice, with more cell death, less cell division and no change to the oestrous cycle. No group sizes or effect sizes are public.
- No dataA patent from the same company reports lesion regression in mice with a compound called Peptide 2. Nothing shows that Peptide 2 is ENDO-205.
In people
none- No dataNo human has published data on ENDO-205, and no trial registration was found in five registries.
- No dataThe planned phase 1 is in healthy women, so it can show safety but not whether lesions shrink.
It is not FDA approved: a trade headline called the March 2026 IND clearance an approval, but an IND only allows trials to begin. Older articles called it a small engineered protein; the company now calls it a peptide, and its grants describe macrocyclic peptides. It is not a conjugate. 'Targets beta-catenin' comes from a patent family not linked to ENDO-205. 'Phase 1 under way' is unconfirmed, and the planned phase 1 is in healthy women, so it will not show whether lesions shrink. FemLUNA, an imaging agent from the same company, is a different product.
The published record
0
Papers and trials about ENDO-205
Europe PMC was searched on 12 October 2026 and returned nothing.
Counted from Europe PMC indexing, not read by a person.
At a glance
Four things to know about ENDO-205
Evidence
Investigational
Category
Sexual and hormonal
Common vial
Varies
Half-life
Nothing published
How much, and do you cycle it?
The range, and whether you take breaks.No human dose disclosed, not established. No established pattern No range
No human dosing exists. The company describes a short course under investigation and says continued dosing may not be needed, but no schedule has been published.
Nothing publishedNo figure
No pharmacokinetic figure in any species has been published. The company says the peptide is optimised for longer residence in diseased tissue, without numbers.
You can compare this against the whole library to see where it sits.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized ENDO-205 keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Any use outside a clinical trial: no human has published data on it and no product exists
- Anyone offered a vial: the sequence is unpublished, so no seller could prove what is in it
Stop and get help
- Not applicable. There is no product and no approved route by which anyone could take it
Common effects
- None known: no human data have been published
- The company reports no safety signals in GLP toxicology studies, without naming the species, doses or duration
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is ENDO-205 approved?
And where the numbers on this page come from.No. ENDO-205 is not approved anywhere and is currently in company-run clinical trials. There is no legal route to obtain it outside a trial.
- Approval statusInvestigational
- RouteNot confirmed for people
- Checked11 October 2026
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesEndoCyclic Therapeutics, IND clearance (PR Newswire, 23 Mar 2026)EndoCyclic Therapeutics, peptide platform pageSBIR.gov, award 1SB1HD118921-01 (2025)SBIR.gov, award 2R44HD100289-04 (2022)SBIR.gov, award 1R44HD100289-01 (2019)US12441768B2, Compositions and methods for treating endometriosisFDA GSRS search, ENDO-205
What has happened recently
Not approved anywhere. EndoCyclic announced FDA clearance of the IND on 23 March 2026 and plans a phase 1 in healthy premenopausal women; no design, size, dose or start date has been disclosed, and no entry was found in ClinicalTrials.gov, ANZCTR, ISRCTN, WHO ICTRP or EU CTIS. NIH has funded the work through four SBIR awards to Endomet Biosciences since 2019, totalling about $7.6 million. No Fast Track or other designation was found.
You can compare this against the whole library, or read how to check a seller.
What else is like ENDO-205?
Others in Sexual and hormonal, side by side.If you're weighing ENDO-205, it's worth reading Goserelin (Zoladex), Leuprolide (Lupron), and Octreotide (Sandostatin) in the same class.
An experimental non-hormonal peptide for endometriosis with an FDA-cleared IND and no human data yet.
- Dose
- No human dose disclosed
- How often
- Not established
A GnRH agonist given as an implant under the skin rather than an injection.
- Dose
- Set by the label
- How often
- Monthly or 3-monthly implant
The GnRH agonist that shuts hormones down by overstimulating them first.
- Dose
- Set by the label and the depot formulation
- How often
- Monthly to six-monthly depot
An approved hormone blocker since 1988: it lowers growth hormone instead of raising it.
- Dose
- 50 to 500 mcg three times daily, or a 10 to 40 mg monthly depot (label)
- How often
- Two to four times daily, or every 4 weeks (depot)
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
- How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.
Sources
- EndoCyclic Therapeutics, IND clearance (PR Newswire, 23 Mar 2026)(2026)FDA cleared the IND. Preclinical work showed elimination of lesions and associated inflammation; no safety signals in GLP toxicology. A phase 1 in healthy premenopausal women is planned.
- EndoCyclic Therapeutics, peptide platform page(2026)Describes uptake through an endocytic pathway active in diseased tissue, pH activation inside cells, and no conjugates or carriers.
- SBIR.gov, award 1SB1HD118921-01 (2025)(2025)$2,045,782 to Endomet Biosciences, naming ENDO-205. Reports lesion regression and disappearance in mice without altering the oestrous cycle.
- SBIR.gov, award 2R44HD100289-04 (2022)(2022)$3,227,492. In vivo lesion regression with more apoptosis and less proliferation, no toxicity, no oestrous cycle change. Aim: find a minimal efficacious dose.
- SBIR.gov, award 1R44HD100289-01 (2019)(2019)First award, describing a panel of macrocyclic peptides that inhibit a downstream component of a pathway contributing to endometriosis.
- US12441768B2, Compositions and methods for treating endometriosis(2025)Endomet Biosciences patent on circularised peptides that bind beta-catenin and block Wnt signalling. Does not mention ENDO-205.
- FDA GSRS search, ENDO-205(2026)No substance record.