EndoCyclic Therapeutics advances non-hormonal endometriosis drug into clinical trials
Will begin human trials following US regulatory clearance
EndoCyclic Therapeutics has received U.S. regulatory clearance to begin human trials of its non-hormonal treatment for endometriosis - marking a step forward for a field long dominated by symptom-managing therapies.
The California-based biopharmaceutical company announced that the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for ENDO-205, its lead candidate targeting endometriosis lesions.
The milestone moves ENDO-205 from preclinical development into first-in-human testing - an early but important stage for a condition that affects an estimated 190 million women globally and has seen relatively limited therapeutic innovation.
The Phase 1 trial will be conducted on healthy premenopausal women as a way to first assess safety and tolerability among humans.
A shift away from hormonal approaches
Endometriosis is typically treated with hormone-based therapies designed to suppress estrogen and manage symptoms such as chronic pelvic pain. While these approaches can offer relief, they do not eliminate the underlying lesions and are often associated with side effects that limit long-term use. Surgery remains common, despite high recurrence rates.
EndoCyclic is positioning ENDO-205 differently. According to the company, the therapy is designed to target endometriosis lesions directly, without altering hormonal pathways or requiring surgical intervention.
“FDA IND clearance validates the strong scientific foundation behind ENDO-205,” said founder and CEO Dr. Tanya Petrossian in a statement.
“We are thrilled to advance ENDO-205 into the clinic… and move closer to bringing patients a much-needed treatment for endometriosis.”
The company describes ENDO-205 as a “precision peptide therapeutic” engineered to act selectively in diseased tissue. In preclinical studies, the candidate demonstrated the ability to reduce endometriosis lesions and associated inflammation, with no safety signals reported in toxicology testing. However, these findings have not yet been validated in humans.
Put simply, EndoCyclic’s approach is based on the idea that the body already has mechanisms to detect and clear abnormal cells - but that process doesn’t always work as it should in diseases like endometriosis.
“Our peptides help restore that surveillance system,” said Petrossian on the company’s website.
“They’re not forcing the body to do something unnatural. They’re helping it recognize what’s out of place and respond appropriately.”
Petrossian also pointed to the broader potential of peptide-based medicines, noting their growing use in other disease areas. And, while peptide-based therapies have gained wider attention in recent years, including in less regulated settings, ENDO-205 is being developed through the conventional clinical trial pathway, with early studies focused on safety.
From academic research to clinical stage
The programme builds on more than a decade of research into disease-modifying approaches for endometriosis. Earlier work underpinning EndoCyclic’s platform has been supported by funding from the National Institutes of Health, including the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
That backing includes Small Business Innovation Research (SBIR) grants and a more recent Commercialization Readiness Pilot award, which the company says received a top impact score - an indicator of scientific and commercial potential.
EndoCyclic has also collaborated with academic researchers, including work exploring how endometriosis develops and progresses at a molecular level. The company’s approach draws on insights more commonly seen in oncology and other complex diseases, focusing on selectively targeting abnormal cellular pathways while sparing healthy tissue.
A broader pipeline in endometriosis care
In addition to ENDO-205, EndoCyclic is developing FemLUNA, an investigational imaging agent intended to improve the detection of endometriosis, including superficial lesions. The company is positioning this as a potential non-invasive alternative to laparoscopy, which remains the current gold standard for diagnosis.
Together, the programmes reflect a broader effort to address both the treatment and diagnostic gaps in endometriosis - a condition where delayed diagnosis and limited therapeutic options continue to shape patient outcomes.