Positive topline results were announced from the phase 3 SPIRIT 1 study investigating relugolix (Myovant Sciences), in combination with estradiol and norethindrone acetate, in women with pain associated with endometriosis.

The 24-week, double-blind, placebo-controlled study evaluated the efficacy and safety of relugolix, an oral gonadotropin-releasing hormone (GnRH) antagonist, plus combination therapy (estradiol 1mg and norethindrone acetate 0.5mg) in more than 1200 women with pain associated with endometriosis. Patients were randomized to receive relugolix 40mg once daily plus combination therapy, relugolix 40g once daily monotherapy for 12 weeks followed by relugolix combination therapy for an additional 12 weeks, or placebo.

Findings from the study showed that relugolix combination therapy was associated with clinically meaningful pain reductions (as assessed by a Numerical Rating Scale score) in 74.5% of patients with dysmenorrhea and 58.5% of patients with nonmenstrual pelvic pain, compared with 26.9% and 39.6% of women treated with placebo, respectively (P <.0001).

Additionally, the study met all key secondary end points achieving statistical significance at week 24 compared with placebo. The key secondary end points included changes in mean dysmenorrhea and overall pelvic pain, impact of pain on daily activities as measured by the Endometriosis Health Profile-30 (EHP-30) pain domain, a greater proportion of patients not using analgesics (P <.0001), changes in mean nonmenstrual pelvic pain (P =.0002), a greater proportion of patients not using opioids (P =.0005), and changes in mean dyspareunia (P =.0149).

With regard to safety, relugolix combination therapy was well tolerated with minimal bone mineral density loss; headache and hot flashes were the most commonly reported side effects. A similar overall incidence of adverse events was observed between the treatment and placebo groups (71.2% vs 66.0%, respectively). Treatment discontinuation was observed in 3.8% of patients in the relugolix combination therapy arm vs 1.9% in the placebo arm.

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Patients who completed the SPIRIT 1 and SPIRIT 2 studies were eligible to enroll in an extension study to receive relugolix combination therapy for an additional 80 weeks. The Company expects 1-year results from the extension study in the first quarter of 2021. “We look forward to sharing the 1-year data from the SPIRIT extension study and submitting a New Drug Application to the FDA for this 1 dose, 1 pill, once a day potential treatment for women with endometriosis,” said Juan Camilo Arjona Ferreira, MD, chief medical officer of Myovant Sciences.

In addition to the endometriosis indication, the Company is investigating relugolix combination therapy for the treatment of women with uterine fibroids and relugolix as monotherapy for men with advanced prostate cancer.

For more information visit myovant.com.