Myovant Sciences is collaborating with Pfizer to develop and sell relugolix for the oncology and women’s health indications in the US and Canada.
Relugolix is an oral gonadotropin-releasing hormone (GnRH) receptor antagonist recently approved in the US for prostate cancer and in late-stage development as a combination tablet with estradiol and norethindrone acetate in endometriosis and uterine fibroids.
Several other companies have entered the female health market with their own oral GnRH antagonist, attempting to capture market share for endometriosis and uterine fibroid indications. They include AbbVie’s FDA-approved Orilissa (elagolix) and ObsEva’s late-stage candidate, linzagolix.
GlobalData believes that the collaboration between Myovant Sciences and Pfizer — announced on 28 December 2020 and worth up to $4.2bn in upfront and milestone payments—will substantially boost the relugolix franchise and intensify competition among these players.
The FDA approved AbbVie’s Orilissa for endometriosis-related pain in April 2018 and as a combination tablet for uterine fibroids in May 2020, securing a first-to-market advantage in both indications. The deal with Pfizer gives Myovant Sciences the opportunity to leverage the US pharma giant’s commercial expertise and strong presence in female health to support relugolix’s penetration in these indications if the treatment receives approval. This is important in light of the sluggish initial uptake of Orilissa.
The deal may also impact ObsEva, which is a relatively new entrant and further behind in development with its own candidate, linzagolix. ObsEva will need to establish a partnership of its own to overcome the difficulties of linzagolix being a potentially third-to-market entrant.
Despite the increasingly stiff competition, oral GnRH antagonists could displace GnRH agonists in the endometriosis and uterine fibroid markets. 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.
However, the biggest advantage of newly developed GnRH antagonists is their oral administration.
According to GlobalData research, endometriosis faces a large unmet need for more effective drugs with long-term safety and tolerability. In the US, the laparoscopy-confirmed diagnosed prevalent cases (ages 12–54 years) are estimated to reach 4,517,265 in 2021 and 4,600,880 by 2025, signifying a big opportunity for companies with even modest product penetration.
The FDA approved relugolix in December 2020 for advanced prostate cancer as the only oral GnRH antagonist for this indication. Relugolix as a combination tablet is under FDA regulatory review for uterine fibroids, with a Prescription Drug User Fee Act (PDUFA) date of June 1, 2021, and a new drug application (NDA) for endometriosis on track for the first half of 2021. ObsEva plans a 1H21 NDA filing in the US for uterine fibroids. The company also recently halted the Phase III endometriosis EDELWEISS 2 study, conducted in the US, due to enrollment difficulties related to the pandemic, though the company plans on pursuing a new Phase III for this indication.