After visiting 10 doctors in New York City, Tanya Petrossian was told she had ovarian cancer. She moved back to California to be close to her family, preparing for surgery and the possibility that her life was about to change permanently.
However, the diagnosis was wrong.
During surgery, physicians discovered not cancer but stage IV endometriosis, a chronic disease that affects an estimated 190 million women worldwide and is notorious for being misdiagnosed, dismissed, or detected only after years of escalating symptoms. Petrossian was told the disease was widespread, likely to recur, and that there was little to offer beyond painkillers, hormones, or repeated surgeries.
For most patients, that is where the story ends. For Petrossian, it was where it began.
A biochemist by training with deep experience in inflammatory disease and systems biology, Petrossian had spent years developing products in women’s health and fertility. She had seen how medicine was practiced differently across clinics and countries, and how entire conditions could remain under-innovated simply because there was no clear path to treat them.
Endometriosis, she realized, was being managed rather than confronted — treated as a hormonal problem or a pain disorder, rather than as a tissue-driven disease with its own biology.
In 2017, Petrossian founded EndoCyclic Therapeutics with a singular goal: to develop the first non-hormonal, disease-modifying therapy for endometriosis. Now, the company is advancing a precision peptide therapeutic designed to selectively target and eliminate endometriotic lesions. The lead candidate, ENDO-205, received FDA investigational new drug (IND) clearance in March 2026, allowing it to move into first-in-human studies.
A disease managed, not treated
Endometriosis is associated with a wide range of debilitating symptoms that can erode quality of life over years or even decades. Chronic pelvic pain, heavy menstrual bleeding, fatigue, urinary problems, abdominal bloating, and gastrointestinal distress are common. The disease also carries a substantial mental health burden, as anxiety, depression, and low mood frequently accompany prolonged pain and diagnostic uncertainty.
For many patients, infertility is another significant burden. Endometriosis is closely linked to subfertility and infertility, pushing many women toward assisted reproductive technologies. Even when pregnancy occurs, risks are higher, with increased rates of miscarriage and ectopic pregnancy.
Despite its prevalence and impact, current treatment for endometriosis focuses on managing pain symptoms rather than addressing the underlying biology of the disease. As of today, there are still no approved disease-modifying therapies capable of stopping, reversing, or curing endometriosis.
For too long, pain alone has been treated as the defining feature of this disease. “I often use a simple analogy: if you put your hand on a fire, the solution isn’t just to take a painkiller while it continues burning. There is a root cause that has to be addressed,” Petrossian told DDN.
The most direct approach for managing endometriosis is surgery — most commonly laparoscopic or keyhole surgery. However, while this can be used to remove visible lesions, recurrence is common. This is in part because microscopic or early-stage lesions are difficult to detect and cannot be safely removed if they cannot be distinguished from healthy tissue.
“A good 80 percent of people get pain relief immediately after surgery,” Petrossian told DDN. “But at one year or five years, many patients are back where they started. That’s often because lesions were missed or incompletely removed — not because surgeons failed, but because some lesions are effectively invisible.”
From systems biology to selective targeting
Petrossian’s background in systems biology led her to question the foundational assumptions guiding endometriosis treatment. Rather than viewing the disease primarily through the lens of hormones or pain, she approached it as a complex, tissue-driven disorder shaped by inflammation, immune dysfunction, and aberrant cell survival.
“I understood early on that hormones don’t act in isolation. They can worsen symptoms, but they aren’t the sole driver of disease, especially in something as tissue driven as endometriosis,” she said. “From a biochemistry standpoint, the question is always: what do hormones bind to, and what pathways do they activate downstream?”
EndoCyclic’s strategy is to exploit molecular features that distinguish endometriotic lesions from surrounding tissue. ENDO-205 is a peptide engineered for selective uptake into endometriotic cells, where it triggers programmed cell death, or apoptosis, after which the body’s own immune system can clear the remaining cellular debris.
“In preclinical studies, what we’ve observed is that once this process is initiated, continued dosing may not be required for the residual tissue to resolve — it effectively sets off a cascade that continues even after the intervention is stopped,” Petrossian said.
This could be really meaningful for both Petrossian and other patients with endometriosis. As she said, “I don’t want to manage this disease forever. I want to take something quickly and be done with the disease.”
Even more excitingly, ENDO-205 demonstrated elimination of endometriosis lesions and associated inflammation in preclinical studies. “When we began our studies and went in to analyze the on-target lesions, we found that they were no longer present. It was, in a sense, a dream scenario but also completely unexpected, and it led us to examine earlier stages of lesion regression, giving us a clearer understanding of how lesions are established and how they resolve over time at a molecular level.”
The program received a rare NIH Commercialization Readiness Pilot grant with a perfect impact score of 10. The award places ENDO-205 among the agency’s most highly rated programs, recognizing both its scientific rigor and commercial potential.
A new pathway for endometriosis treatment
Historically, the lack of a clear regulatory or commercial pathway has discouraged investment in endometriosis drug development. Without precedents for disease-modifying therapies, companies have been reluctant to take on the perceived risk. That has begun to change as awareness grows — driven in part by patients and advocates who have pushed the disease into the public conversation.
“As more people have begun to talk about and advocate for endometriosis, the field has started to shift,” said Petrossian. “You now see serious interest from industry and investors — people at places like JPMorgan discussing endometriosis as potentially the next GLP-1-scale opportunity in women’s health. That signals a broader change in perception.”
EndoCyclic’s IND clearance shows that a regulatory path is possible. The company worked closely with the FDA to define appropriate endpoints and development plans for a condition that does not fit neatly into existing therapeutic categories.
Diagnostics as well as treatment
As the team refined its peptide platform, a second opportunity emerged. The same principles that allow selective uptake into endometriotic tissue could also be used to improve diagnosis.
“One of the biggest problems in endometriosis is that clinicians often don’t know where lesions are located. In my own case, there was uncertainty about whether the disease was affecting my fallopian tubes, appendix, or elsewhere,” said Petrossian.
Without knowing where lesions are implanted, symptoms are easily misinterpreted. Bladder lesions can mimic recurrent infections, while those on the appendix can present as acute appendicitis. “That diagnostic uncertainty drove us to adapt our peptide technology for imaging as well as therapy,” Petrossian noted.
EndoCyclic is also developing a separate, non-radioactive imaging agent called FemLUNA, designed to detect endometriosis lesions, with the potential to enable clinicians to visualize, size and stage lesions earlier and more accurately without surgery.
Better imaging could have downstream effects on both care and clinical trials. Earlier detection may reduce years long diagnostic delays, while precise lesion mapping could improve surgical outcomes and help establish a potential clinical endpoint for trials.
A different vision of care
Much remains to be tested in humans. But the conceptual shift — from symptom management to tissue elimination, and from blind treatment to targeted intervention — could redefine what endometriosis treatment looks like altogether.
Petrossian is careful not to overstate what the data can support. “We’re dealing with patients’ lives and expectations. That’s one reason we stayed largely under the radar during a decade of preclinical development, until we had something concrete to show — our IND clearance, which itself required a very large, rigorously built regulatory package.”
If it translates successfully into the clinic, the implications would extend far beyond a new therapy. It would represent a shift in ambition for endometriosis itself — from managing a chronic condition to interrupting the biology that drives it, potentially changing outcomes for millions of women worldwide.
