Bayer aims Mirena at women's health issue with no treatment

Bayer has started a phase 3 trial of its intrauterine contraceptive Mirena in an endometrial condition that can lead to complications, including cancer, but has no approved therapies.

The condition – known as nonatypical endometrial hyperplasia (NAEH) – is a benign form of thickening in the lining of the uterus believed to be caused by an imbalance between oestrogen and progesterone hormone levels.

The nonatypical form is less likely to become cancerous than cases where the cells are atypical, but can still go on to become atypical and cause cancer if untreated with a risk of the tumour going undetected.

The recommended treatment for atypical forms is a hysterectomy in many countries, and while some form of intrauterine hormonal therapy is recommended in some – including the UK – no such intervention has been tested in a large-scale, prospective trial.

To remedy that, Bayer has launched the SUNFLOWER trial of its Mirena device, containing 52mg of the oestrogen hormone oestradiol, which will be compared to an oral progestin control in 207 women with NAEH in three countries.

It will take around one-and-a-half years to complete, with the primary endpoint complete resolution of endometrial hyperplasia. Secondary endpoints will include recurrence and progression of NAEH after a complete response and the proportion of patients who go on to have a hysterectomy.

According to Bayer, the annual incidence of NAEH ranges from 121 to 270 per 100.000 women depending on the geography, age and menopause status, while a paper in the Journal of Obstetrics, Gynaecology, & Cancer Research last year suggested there are around 200,000 new cases of both types endometrial hyperplasia in developed countries each year.

The Mirena product family has been on the market for decades with a strong of approved indications including pregnancy prevention, heavy menstrual bleeding, endometrial protection during oestrogen therapy for menopausal symptoms, and menstrual pain, and is sold in more than 120 countries.

Despite its age, it remains the cornerstone of Bayer's women's health business, with sales rising 15% to €1.04 billion ($1.21 billion) in the first nine months of the year.

"Having a leading position in global women's health we are committed to advance science focusing on innovative options to address the unmet medical need of women globally," said Christian Rommel, head of R&D at Bayer's pharma division.

"With this new phase 3 study, we are now expanding our broad clinical development programme for intrauterine systems to be able to support women suffering from nonatypical endometrial hyperplasia with an effective treatment," he added.

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