Myovant Sciences’ deal with Pfizer to co-develop and commercialize oral GnRH antagonist relugolix in oncology and women’s health in the US and Canada will substantially boost the relugolix franchise and intensify competition in the female health space, according to GlobalData, a leading data and analytics company.

Kelly Lambrinos, Managing Analyst at GlobalData comments: “Key players AbbVie, Myovant and ObsEva are each pursuing their own oral GnRH antagonist in endometriosis and uterine fibroids. The deal with Pfizer gives Myovant the opportunity to leverage the US pharma giant’s commercial experience and expertise to support relugolix’s market position and competitiveness against AbbVie’s Orilissa, which has already secured a first-to-market advantage over competitors after gaining FDA approval for endometriosis and uterine fibroids.

“The deal will enhance Myovant’s financial position and boost relugolix’s potential launch through a strong commercial strategy stemming from Pfizer’s historical presence in the female health space, which has boasted a lucrative women’s health portfolio. However, the deal also has implications on ObsEva’s own GnRH antagonist, linzagolix, which is currently in late-stage development for both indications and will experience additional competition from Myovant.

“ObsEva will need to establish a partnership of its own to combat future difficulties penetrating the market as a third-to-market entrant, if linzagolix gains approval in these indications. However, the endometriosis space faces a large unmet need for more effective drugs with long-term safety and tolerability, signifying the large market opportunity for competing companies even with modest product penetration.”

The laparoscopy-confirmed diagnosed US prevalent cases (ages 12–54 years) are estimated to reach 4,517,265 in 2021 and 4,600,880 by 2025, according to GlobalData research.

Lambrinos adds: “Despite the increasingly stiffer competition in the space, oral GnRH antagonists have the potential to displace GnRH agonists in the endometriosis and uterine fibroid space. GnRH antagonists allow for the rapid onset of estrogen suppression—the hormone known to stimulate the growth of uterine fibroids or endometriosis—without the hormonal flare effect seen with GnRH agonists. The biggest advantage, however, of newly developed GnRH antagonists is their oral route of administration.”

ObsEva recently halted the endometriosis Phase III EDELWEISS 2 study, conducted in the US, due to enrollment difficulties related to the pandemic, though the company plans on conducting a new Phase III and maintaining the original NDA filing timelines for this indication.