FDA approves combination therapy for endometriosis

By Sneha Mavis

The US Food and Drug Administration (FDA) approved the combination therapy relugolix 40 mg, estradiol 1 mg, and norethindrone acetate 0.5 mg (MYFEMBREE) for the treatment of moderate to severe pain associated with ENDOMETRIOSIS among premenopausal women for up to 24 months, according to a release from Pfizer. 

Endometriosis is commonly accompanied by debilitating symptoms. The condition is characterized by the existence of uterine tissue outside of the uterine cavity, which causes painful symptoms such as painful periods, lower back and abdominal pain, heavy menstrual cramps, and painful intercourse.

The latest FDA approval for the once-daily oral medicine, which was made public by Pfizer on August 5, is based on the outcomes of the phase 3 SPIRIT program. The FDA had previously approved it for the treatment of excessive menstrual bleeding brought on by uterine fibroids among premenopausal women.

"The data from the SPIRIT studies demonstrated the clinical effects that relugolix combined treatment could have on moderate to serious endometriosis-related pain and how it can benefit patients," stated Linda Giudice, MD, Ph.D., Distinguished Professor at the University of California, San Francisco (UCSF), and Chair of the SPIRIT Program Steering Committee, in a release. "This recently approved treatment option for endometriosis pain offers the convenience of one pill taken once a day with a mean change in the bone mineral density with less than 1% which did not appear to deteriorate at 12 months of treatment; nevertheless, monitoring is recommended."

The SPIRIT program, which Pfizer and Myovant jointly commercialized, was utilized for the most recent approval of MYFEMBREE. It comprised the phase 3 SPIRT 1 and SPIRT 2 trials as well as the initial 28 weeks of an open-label extension study amongst women who completed SPIRT 1 or SPIRT 2. In the SPIRT 1 and SPIRIT 2 trials, more than 1200 women with endometriosis-related pain were enrolled. Both trials met their coprimary objectives, with 75% of the MYFEMBREE groups seeing a clinically significant decrease in dysmenorrhea at Week 24 compared to 27% and 30% of the placebo groups, respectively (both P.0001).

Among the other notable aspects of the program mentioned in the statement was the clinically significant decrease in nonmenstrual pelvic distress in 59% and 66% of women as opposed to 40% and 43% of women in the placebo groups (P .0001). In these trials' safety evaluations, side effects such as arthralgia, headache, vasomotor symptoms, mood disturbances, abnormal uterine bleeding, nausea, toothache, backache, decreased sexual desire and arousal, exhaustion, and dizziness were found to occur in at least 3% of the women receiving MYFEMBREE and to be more common than placebo.