WHAT MAKES CE/BZA DIFFERENT FROM TRADITIONAL EPT?
Dr Pinkerton: There are two exciting differences:
• The incidences of breast pain and tenderness were found to be similar to placebo and were significantly lower than those with the comparator EPT (conjugated estrogens 0.45 mg plus medroxyprogesterone acetate [CE/MPA] 1.5 mg).9,10,12
• Bleeding and spotting rates were significantly lower than those found with CE/MPA.13
In addition, high rates of amenorrhea have been found—comparable to placebo.13
CE/BZA is similar to traditional EPT in several ways. For instance, compared with placebo, at two years, CE/BZA was not found to increase the incidence of endometrial hyperplasia, endometrial thickness (increase from baseline was < 1 mm and comparable to placebo), or endometrial cancers.14 Lastly, similar to EPT, there is probably a twofold risk for venous thromboembolism (VTE) with BZA 20 mg alone.15 Importantly, there has been no additive effect on VTE risk when combining CE with BZA; however, we will need longer studies, in older women, to fully evaluate this risk.1
Overall, in symptomatic postmenopausal women with a uterus, randomized controlled data show the same improvement with CE/BZA as that seen with traditional oral EPTs, with improvements in hot flashes; night sweats, with fewer sleep disruptions; and prevention of bone loss. In addition, the changes in cholesterol (an increase in triglyceride levels) and effect on the vagina are the same. Yet, CE/BZA appears to have a neutral effect on the breast and protects against endometrial hyperplasia and endometrial cancer without causing bleeding.9,10 CE/BZA’s VTE and stroke risks are expected to be similar to traditional oral EPT.
Therefore, the major benefit of CE/BZA for women who have a uterus is the lack of significant breast tenderness, lack of changes in breast density, and lack of vaginal bleeding that is often seen with traditional EPT.12
THEN, IS PROGESTOGEN THE HARMFUL AGENT IN TRADITIONAL HT OPTIONS?
Dr Pinkerton: There is evidence that estrogen plus progestogen therapy has more risk for breast cancer than estrogen alone. But in women who have a uterus, you need to protect against uterine cancer so, up until now, the only option was to add progestogen. Some studies suggest the risk for breast cancer may differ depending on the type of progestogen. So it’s a laudable goal to try to protect the endometrium without using a progestogen.
GIVEN ITS SAFETY PROFILE, DO YOU SEE CE/BZA BEING INDICATED FOR WOMEN WITHOUT A UTERUS?
Dr Pinkerton: CE/BZA has been tested only in women with a uterus; there is no indication for using it in hysterectomized women. In the future, unless trial data show a benefit to hysterectomized women—by a reduction in breast cancer compared with estrogen alone—there would be no reason to add BZA to the CE for these women. You would just use CE or another type of estrogen alone.
DO YOU ANTICIPATE BZA BEING USED ALONE?
Dr Pinkerton: For treating osteoporosis in postmenopausal women at increased risk for fracture, BZA alone has greater benefits than risks. It is approved in other countries to prevent or treat osteoporosis. In 2008, Wyeth received an approval letter from the FDA for BZA alone but, for whatever reason, the drug was not brought to market. BZA reduces the number of new lumbar spine fractures by 4% (vs 2% for placebo), with efficacy better in those with a higher risk for fractures. Like raloxifene, it has not been shown effective at reducing nonvertebral fractures, although it maintains spinal bone density.16
BZA available as monotherapy could tempt clinicians to pair it with other estrogens. We must recognize that the combination of the specific estrogen and BZA dose and type need to be balanced to provide endometrial hyperplasia protection. It would not be safe or effective to take BZA as a selective estrogen-receptor modulator and pair it with any other untested systemic estrogen. I do not anticipate, in this country, that BZA will become available as monotherapy, however.
NEW OPTIONS ARE WELCOME
Dr Moore: Novel strategies for clinicians to optimally treat menopausal symptoms are always welcome. I look forward to more data from the SMART trials on CE/BZA and to moving forward as we gain experience with using this new treatment option.
REFERENCES
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2. Pinkerton JV, Utian WH, Constantine GD, et al. Relief of vasomotor symptoms with the tissue-selective estrogen complex containing bazedoxifene/conjugated estrogens. Menopause. 2009;16(6): 1116–1124.
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