Selective Progesterone Receptor Modulator(ulipristal acetate – a new option in the pharmacological treatment of uterine fibroids in women

Abstract

Uterine leiomyomata (fibroids) are very common, mostly benign tumors in women of reproductive age. Symptomatic fibroids cause significant morbidity and are characterized by heavy, prolonged menstrual bleeding, by pain and pelvic pressure and, in some cases, they may lead to reproductive dysfunctions. Up to date, surgical procedures (hysterectomy or myomectomy) have been the dominant managements but recently uterine artery embolization and focused ultrasound surgery have also been taken into consideration. Hysterectomy is curative but for women of reproductive age the need for uterus-sparing medical therapy is evident. There are convincing data that progesterone and its receptors increase the proliferation activity of the cells in uterine leiomyomata, hence treatment with antiprogestins and progesterone receptor modulators seems to be reasonable. Results of a successfully completed phase III clinical trials with the application of ulipristal acetate (UPA) (firstin-class selective progesterone receptor modulator –SPRM) have been published at the beginning of this year. Administration of 5mg or 10 mg UPA daily has been shown to rapidly stop (within a week) excessive uterine bleeding, reduce the volume of the three largest fibroids by -44.8% and -54.8% for UPA 5mg and 10 mg, respectively. The effect on fibroid volume has been observed for up to 6 months after treatment cessation. It is also important that UPA restores patient Quality of Life scores to the level of healthy women and in the majority of patients resumes menstruation and ovulation within one month after treatment cessation. When compared with the Gn-RH agonist (leuprolide acetate), UPA has controlled uterine bleeding faster and more consistently (7 days vs. 30 days), fibroid reduction for up to 6 months has been smaller for Gn-RH a (-16.5%) and UPA has shown a superior safety profile as estradiol levels are maintained in the mid-follicular range. The UPA has caused temporary changes in endometrial morphology but 6 month after the treatment the endometrium returned to normal histology in the majority of cases. The presented results on the application UPA in the medical treatment of symptomatic uterine fibroids are very promising and gynecologists are given a new treatment option.