ORLANDO – An oral combination of naturally-occurring estrogen and progesterone was found safe and effective for treatment of hot flashes in postmenopausal women with an intact uterus.

The phase III trial results represent another step toward approval of a formulation of bioidentical hormone therapy (HT) by the Food and Drug Administration.

“No similar combined HT has been approved in the U.S.; however, compounded bioidentical HT is estimated to have become the most prevalent HT by U.S. prescription volume,” Rogerio Lobo, MD, professor of obstetrics and gynecology at Columbia University, New York, wrote in an abstract accompanying the study. He presented his findings at the annual meeting of the Endocrine Society.

The study enrolled 1,835 patients, of whom 89% completed the efficacy portion of the study. The estrogen-progesterone combination significantly reduced hot flashes, compared with placebo (P less than .05 for all doses at 12 weeks), with the higher two of four different combination doses resulting in significant differences by study week 4. Menopause-related quality of life was also significantly improved by study week 12 for all doses (P less than .05, compared with placebo).

Up to 39 million prescriptions annually may be written for up to 2.5 million women in the United States, Dr. Lobo said. None of the currently available formulations of 17 beta-estradiol and progesterone are FDA approved. The medication studied – dubbed TX-001HR and produced by TherapeuticsMD – combines the two hormones in an oral capsule.

The REPLENISH trial was designed to evaluate the efficacy and safety of four different dose combinations of estradiol (E2) and progesterone (P4), compared with placebo, to treat moderate to severe vasomotor symptoms in postmenopausal women.

The phase III randomized, double-blind, placebo-controlled trial of the E2/P4 combination in postmenopausal women with an intact uterus had an efficacy portion of the study that lasted 12 weeks; endometrial safety was followed for 1 year in a smaller subset of patients.

The dose-ranging study design randomized women 1:1:1:1:1 to one of four combinations of E2 and P4, or to placebo. The four active treatment groups received either 1.0 mg E2/100 mg P4, 0.5 mg E2/100 mg P4, 0.5 mg E2/50 mg P4, or 0.25 mg E2/50 mg P4. There was no active comparator.

The safety portion of the study could include women whose vasomotor severity did not qualify them for the efficacy substudy; there was no placebo in this arm of the study.

Women participating in the vasomotor menopausal symptom (VMS) portion of the study kept a daily symptom diary and completed the Menopause-Specific Quality of Life (MENQOL) questionnaire as an objective measure of menopause-related symptomatology.

The study’s primary efficacy endpoints were VMS frequency and severity, tracked by measuring the mean change from baseline at study weeks 4 and 12. The secondary endpoint was the mean change in VMS frequency and severity week to week, compared with baseline. Patients were included in the modified intention-to-treat population if they took at least one dose of study drug and had at least 5 days of baseline diary data as well as at least 4 days of diary data in one on-treatment week.

The safety cohort included all women who took at least one capsule of the study drug, and tracked the incidence of endometrial hyperplasia out to 12 months for those who participated in the extended safety portion of the trial. The secondary endpoint was the incidence of other adverse events and serious adverse events.

All four dose combinations “provided statistically and clinically significant reduction in the weekly frequency of moderate to severe VMS from baseline at weeks 4 and 12, compared with placebo,” Dr. Lobo said. The lone exception, he said, was the lowest dose combination, which didn’t produce significant VMS reduction until study week 6.

Looking at the week-by-week improvement measure, the 1.0 mg E2/100 mg P4 and the 0.5 mg E2/100 mg P4 formulations improved VMS severity at weeks 4 and 12, compared with placebo.

Quality of life as measured by the MENQOL was significantly improved by all doses by study week 12, compared with placebo. Participants also reported significant improvement on the vasomotor domain of the MENQOL.

There was no endometrial hyperplasia in any study subject, nor were any malignancies detected in any study participant, Dr. Lobo said. The most frequently reported treatment-emergent adverse events were headaches, nasopharyngitis, breast tenderness, upper respiratory tract infection, nausea, back pain, and abdominal pain. Though seven serious treatment-emergent adverse events were considered treatment-related, “no unexpected safety signals were observed,” Dr. Lobo said.

To be included, postmenopausal women aged 40-65 years needed to have an intact uterus and be generally healthy, with a body mass index of less than 35 kg/m². They also underwent an endometrial biopsy before participating. Their VMS had to occur at least seven times daily, or 50 times in a week, and be moderate to severe in intensity.

Patients with endometrial hyperplasia or melanoma, as well as women with uterine, endometrial, ovarian, or breast cancer, were excluded from the study, as were women with cardiovascular, hepatic, or renal disorders. Women with diabetes and those with thyroid disorders also were excluded.

Though women could have used sex hormone–containing or –modifying medications, they had to cease those medications for a variable washout period before beginning the study. The mean age of study participants was 55, and their mean BMI was 27. Two-thirds of the women were white.

“TX-001HR, if approved, would be a new oral hormone therapy option for postmenopausal women with moderate to severe vasomotor symptoms with an intact uterus,” Dr. Lobo said.

The drug, he said, could present an option in bioidentical hormones – one that has been evaluated for safety and efficacy – for women who are currently using “less regulated and unapproved compounded bioidentical hormone therapy.”

Dr. Lobo reported receiving research support from TherapeuticsMD, which funded the study.

koakes@frontlinemedcom.com

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Bioidentical hormone replacement fares well in phase III trial