Endometriosis Pain Treatment Pipeline Shows Mixed Results as NHS Approves First Daily Oral Therapy

Key Insights

• The NHS in England has approved relugolix combination therapy as the first long-term daily oral treatment for endometriosis, expected to benefit around 1,000 women annually whose symptoms persist despite previous treatments.
• Organon discontinued development of OG-6219 after the drug candidate failed its Phase 2 trial in July 2025, despite being acquired for $75 million and previously described as the company's "biggest potential opportunity."
• Hope Medicine's HMI-115, a first-in-class monoclonal antibody targeting the prolactin receptor, reported positive interim Phase II results and received Breakthrough Therapy Designation from China's NMPA.

The endometriosis pain treatment landscape experienced significant developments in 2024 and 2025, marked by both regulatory approvals and clinical trial setbacks that highlight the ongoing challenges in developing effective therapies for this debilitating condition.

NHS Approves First Daily Oral Treatment

In March 2025, the National Institute for Health and Care Excellence (NICE) recommended relugolix-estradiol-norethisterone, also known as relugolix combination therapy (relugolix CT), for routine use on the NHS in England. This marks the first time a daily pill of this kind has been approved for long-term endometriosis management by the NHS, with around 1,000 women expected to benefit each year.

The final draft guidance advised that the combination therapy should be offered to adults of reproductive age whose endometriosis symptoms persist despite previous medical or surgical treatments, representing a significant milestone in endometriosis care accessibility.

Major Clinical Trial Failure

Organon faced a significant setback in July 2025 when its drug candidate OG-6219 failed in a Phase 2 clinical trial, leading the company to discontinue its development for endometriosis. The women's health-focused company had acquired the candidate through its $75 million acquisition of Forendo Pharma in 2021, shortly after spinning off from Merck & Co.

The company launched a Phase 2 trial in 2022, enrolling 354 premenopausal women suffering from moderate to severe endometriosis-related pain. Participants were randomized to receive one of three doses of OG-6219 or a placebo. Organon had hoped the drug would alleviate pain by inhibiting a hormone involved in uterine tissue growth and inflammation, but the trial failed to meet expectations.

Promising Pipeline Developments

Hope Medicine Inc. reported positive findings from an interim analysis of its global Phase II trial evaluating HMI-115 in October 2024. The study, titled "A Randomized, Multicenter, Double-Blind, Placebo-Controlled Phase 2 Study to Evaluate the Safety and Efficacy of HMI-115 in Women with Moderate to Severe Endometriosis-Associated Pain Over a 12-Week Treatment Period," demonstrated encouraging results for this first-in-class therapy.

HMI-115, a monoclonal antibody that inhibits the prolactin receptor, represents a novel therapeutic approach for endometriosis. The National Medical Products Administration (NMPA) in China has granted HMI-115 Breakthrough Therapy Designation, underscoring its potential clinical significance.

TiumBio Co., Ltd. also reported positive topline results from its Phase 2a clinical trial evaluating Merigolix in May 2024. The oral gonadotropin-releasing hormone (GnRH) receptor antagonist showed promise for treating moderate to severe endometriosis-associated pain.

Innovative Research Collaborations

Lisata Therapeutics, Inc. entered into a sponsored research collaboration with the University of Cincinnati in October 2024 to explore its innovative cyclic peptide candidate, certepetide, in combination with bevacizumab (a VEGF inhibitor). The study will utilize a preclinical animal model to evaluate the potential of this combination therapy for treating endometriosis.

Gynica, an Israeli company, plans to administer the first dose in a Phase I trial for its cannabinoid-based therapies, IntraVagS301 and IntraVagS302, designed for endometriosis by the end of 2024. This trial aims to assess the safety, toxicity, and pharmacokinetics of these drugs, which utilize microencapsulation technology.

Diverse Pipeline Landscape

According to DelveInsight's assessment, the global endometriosis pain pipeline constitutes more than five key companies continuously working towards developing more than five endometriosis pain treatment therapies. Companies actively developing therapies include Organon, Ironwood Pharmaceuticals, Mitsubishi Tanabe Pharma Corporation, AbbVie/Neurocrine Biosciences, ObsEva/Kissei Pharmaceuticals, SWK/Enteris BioPharma, Bayer/Hope Medicine, and Tiumbio.

Emerging therapies in different phases of clinical trials include FOR 6219, IW-3300, MT-2990, ORIAHNN (elagolix/estradiol/norethindrone acetate), Linzagolix (OBE2109), OVAREST (leuprorelin oral), HMI-115, TU2670 (NCE-403), and others that are expected to have a significant impact on the endometriosis pain market in the coming years.

Market Challenges and Opportunities

The development of drug delivery systems represents a new approach in pain treatment among endometriosis patients, with extensive research on non-steroidal anti-inflammatory drugs fueling market growth. However, challenges remain, including a less robust pipeline, high cost of treatment procedures, and other factors creating obstacles in market growth.

Endometriosis pain refers to the discomfort, cramping, and other symptoms experienced by individuals with endometriosis, a condition where tissue similar to the lining of the uterus grows outside the uterus. The pain can vary widely in intensity and may occur before, during, or after menstruation, manifesting as chronic pelvic pain, lower back pain, and pain during bowel movements or urination.