Written By: Pharmacally Medical News Desk
Bayer has initiated the Phase III SUNFLOWER clinical trial to evaluate the efficacy and safety of its 52mg levonorgestrel-releasing intrauterine system (LNG-IUS), Mirena, in treating nonatypical endometrial hyperplasia (NAEH) in women. As of now there is no FDA-approved medical therapies currently exist for NAEH in the United States.
NAEH involves abnormal thickening of the uterine lining due to estrogen-progesterone imbalance, without cancerous cell changes. It affects 121 to 270 women per 100,000 annually, varying by geography, age, and menopause status, and may present asymptomatically or with heavy, irregular, or postmenopausal bleeding. Untreated NAEH risks progression to atypical hyperplasia or uterine cancer, underscoring the urgency for effective interventions.
The SUNFLOWER trial (NCT06904274) is a Phase III investigational clinical study comparing Mirena against an oral progestin for NAEH treatment. The study plans to enroll 207 participants at approximately 90 sites across three countries, with completion anticipated in about 18 months.
Christian Rommel, Ph.D., Head of R&D at Bayer Pharmaceuticals stated that Bayer is committed to advancing women’s health by developing innovative treatments. The new Phase III study expands their clinical program for intrauterine systems to provide an effective treatment option for women with nonatypical endometrial hyperplasia.
Mirena, a 52mg LNG-IUS, is approved in the US for pregnancy prevention up to 8 years and heavy menstrual bleeding management up to 5 years in women choosing intrauterine contraception. It is available in more than 120 countries worldwide, with indications varying by region, including contraception, heavy menstrual bleeding, and endometrial protection during estrogen therapy, and dysmenorrhea. Bayer emphasized that Mirena is not currently approved by the FDA for NAEH treatment.
References
Bayer starts Phase III study with long-acting reversible intrauterine system for treatment of nonatypical endometrial hyperplasia, 02 December 2025, https://www.bayer.com/media/en-us/bayer-starts-phase-iii-study-with-mirena-52mg-lng–ius-for-treatment-of-nonatypical-endometrial-hyperplasia/
Mirena for the Treatment of Nonatypical Endometrial Hyperplasia for 6 Months (SUNFLOWER), ClinicalTrials.gov ID NCT06904274, https://www.clinicaltrials.gov/study/NCT06904274