Abbott Laboratories and partner Neurocrine Biosciences are beginning a late-stage trial of their investigational endometriosis treatment elagolix.

The firms have announced a 24-week Phase III trial of elagolix, an oral gonadotropin-releasing hormone (GnRH) antagonist in 875 women aged 18-49, with moderate-to-severe endometriosis-associated pain. It will be conducted at around 160 sites in the USA, Puerto Rico and Canada.

Rita Jain, head of pain, respiratory and metabolic development at Abbott, said the investigation of elagolix "is an important step in the exploration of potential treatments for this underserved patient population". She added that the Phase III trial has begun screening for enrollment and a second late-stage study is being planned. The firm hopes to file a New Drug Application in 2016.

Abbott bagged rights to elagolix in June 2010 and the deal could be worth $575 million to Neurocrine. It has been estimated that 100 million women worldwide suffer from endometriosis, which is associated with a multitude of symptoms. Some of the most common include pain related both to menstruation as well as chronic pelvic pain throughout the menstrual cycle, and is a leading cause of infertility.

Abbott also noted that the annual direct and indirect costs of endometriosis are estimated to exceed $20 billion in the USA alone.