Clinical Trial Suggests Menopause Drug Duavee Could Help Prevent Invasive Breast Cancer

An innovative clinical trial spearheaded by researchers at Northwestern Medicine has revealed unexpected potential for a drug already approved to treat menopausal symptoms. The findings, soon to be presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, suggest that Duavee — a combination therapy of conjugated estrogens and bazedoxifene — could slow the progression of certain pre-invasive breast lesions, potentially preventing the evolution into invasive breast cancer.

Duavee’s dual action tackles menopausal discomfort while exhibiting biologically significant effects on breast tissue. Postmenopausal women diagnosed with ductal carcinoma in situ (DCIS), a non-invasive breast condition widely regarded as a precursor to invasive breast cancer, participated in the trial. DCIS affects approximately 60,000 women annually in the United States alone, representing a substantial population at risk. This phase 2 trial randomized 141 women across ten clinical sites to receive either Duavee or a placebo during a critical window between diagnosis and surgical intervention.

The scientific rationale behind this study centers on the modulation of hormone receptors in breast tissue. Estrogens influence cellular proliferation, and selective estrogen receptor modulators like bazedoxifene are designed to mitigate estrogen’s unwanted effects in the breast while providing beneficial effects elsewhere in the body, such as bone preservation. By combining these agents, Duavee offers a nuanced hormonal environment that was observed to reduce markers indicative of cellular proliferation in breast tissue samples, which are highly predictive of the risk of malignant transformation.

According to Dr. Swati Kulkarni, the lead investigator and a professor of breast surgery at Northwestern University Feinberg School of Medicine, the reduction in cell growth rates observed in the Duavee-treated group is a promising biomarker change indicative of hindered cancer progression pathways. This represents a significant breakthrough as current medications for breast cancer prevention often involve considerable side effects that lead many women to forego prophylactic treatment.

Critically, Duavee’s tolerability profile in this trial appeared favorable. Unlike other hormone-based preventive therapies known for inducing menopausal symptom exacerbation or other systemic side effects, participants receiving Duavee did not report a decline in quality of life. This tolerability could lead to improved adherence and acceptance among women facing the challenge of balancing menopausal management with breast cancer risk reduction.

The target population for this intervention encompasses women with a history of high-risk breast lesions, including atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS), as well as prior diagnoses of DCIS. These conditions elevate the lifetime risk of invasive breast cancer substantially. Women in this demographic group typically have limited options for hormone therapy during menopause due to concerns about triggering cancerous changes, making Duavee a potentially valuable therapeutic alternative.

The mechanism by which Duavee affects breast tissue involves selective modulation at the estrogen receptor level. Conjugated estrogens provide hormone replacement to alleviate menopausal symptoms, while bazedoxifene acts as an estrogen receptor antagonist specifically in breast and uterine tissue, preventing potential proliferative effects. This complex interplay may disrupt the estrogen-driven pathways responsible for cellular overgrowth, thereby curbing neoplastic progression without compromising systemic estrogen benefits.

This trial’s methodology included administering Duavee or placebo for approximately four weeks, a relatively brief preoperative period allowing precise examination of acute biological effects on breast tissue sampled during surgery. Despite the short duration, the significant decrease in cell proliferation markers underscores a robust biological response, suggesting the potential for even greater benefits with extended therapy, pending future studies.

While these results are compelling, Dr. Kulkarni emphasizes the necessity for larger scale trials with extended follow-up to validate long-term efficacy and safety before recommending Duavee as a standard preventive therapy. The existing FDA approval and widespread clinical availability of Duavee, however, expedite the potential translational impact should future research corroborate these findings.

The broader implications of this research are profound, as it bridges menopausal symptom management and cancer prevention—two domains often treated disparately despite their clinical intersection. The availability of a well-tolerated, dual-purpose medication could revolutionize the approach to care in a vulnerable demographic of postmenopausal women at elevated breast cancer risk.

This study also exemplifies the value of repurposing existing drugs with well-characterized safety profiles, potentially accelerating access to new clinical applications without the lengthy drug development timelines typically required. Such strategies are especially important in oncology, where prevention remains a critical yet underutilized avenue.

In summary, the Northwestern-led clinical trial presents a promising new frontier in breast cancer prevention. Duavee’s ability to slow cellular proliferation in DCIS lesions, coupled with its menopausal symptom relief and favorable side effect profile, highlights its potential as a transformative option. As more comprehensive data emerges, this therapy may become a cornerstone in reducing invasive breast cancer incidence among high-risk postmenopausal women, ultimately improving both longevity and quality of life.

News Publication Date: June 1, 2025

Web References:

• Northwestern Medicine Faculty Profile: Dr. Swati Kulkarni
• Clinical Trial Registration: NCT02694809
• ASCO Annual Meeting Presentation Details: ASCO 2025 Meeting
• Breast Cancer Research Foundation on DCIS: About DCIS