Actively Recruiting

Phase 2
Age: 35Years +
FEMALE
NCT05941520

Acolbifene Versus Low Dose Tamoxifen for the Prevention of Breast Cancer in Premenopausal Women at High Risk for Development of Breast Cancer

Led by National Cancer Institute (NCI) · Updated on 2026-05-13

80

Participants Needed

4

Research Sites

210 weeks

Total Duration

On this page

AI-Summary

What this Trial Is About

This phase IIA trial compares the effect of acolbifene versus low dose tamoxifen in preventing breast cancer in premenopausal women at high risk for developing breast cancer. The usual approach for patients at increased risk for breast cancer is to undergo yearly breast magnetic resonance imaging or ultrasound in addition to yearly mammogram. Premenopausal women at very high lifetime risk for breast cancer (greater than 50%) can consider preventive removal (mastectomy) of both breasts. Premenopausal women age 35 or older with a prior diagnosis of atypical hyperplasia, lobular carcinoma in situ, or an estimated 10-year risk of greater than or equal to 3% or estimated 10-year risk of greater than or equal to 2-5 times that of the average woman (depending on age) may be advised to consider five years of standard dose tamoxifen. Standard dose tamoxifen is four times the dose used in this study. Estrogen can cause the development and growth of breast cancer cells. Acolbifene and tamoxifen blocks the use of estrogen by breast cells. This study may help researchers measure the effects of acolbifene and low dose tamoxifen on markers of breast cancer risk in mammogram imaging, breast tissue, and in blood samples.

CONDITIONS

Official Title

Acolbifene Versus Low Dose Tamoxifen for the Prevention of Breast Cancer in Premenopausal Women at High Risk for Development of Breast Cancer

Who Can Participate

Age: 35Years +
FEMALE

Eligibility Criteria

Eligible

You may qualify if you...

  • Age 35 years or older
  • Clinically premenopausal women
  • Regular menstrual cycles between 21 and 35 days, or using a progestin-containing contraceptive device that suppresses periods, or hysterectomy with ovaries intact
  • Not planning pregnancy for at least 12 months
  • Women of child-bearing potential willing to use effective birth control starting 8 weeks before fine needle aspiration and continuing for 8 weeks after study completion
  • Increased breast cancer risk due to prior atypical hyperplasia, lobular carcinoma in situ, ductal carcinoma in situ treated at least 3 months prior, high-risk gene mutations (excluding BRCA1/2 and PALB2), high polygenic risk score, family history of breast cancer, or high mammographic density
  • At least one unaffected untreated breast available for fine needle aspiration
  • ECOG performance status 0 to 2 or Karnofsky score 60% or higher
  • Total bilirubin, AST, ALT less than or equal to 1.5 times institutional upper limit of normal within 180 days prior to randomization
  • Creatinine less than or equal to 2.0 mg/dL within 180 days prior to randomization
  • Willingness and ability to comply with study visits, treatment plans, and procedures
  • Ability to understand and sign informed consent
Not Eligible

You will not qualify if you...

  • Bilateral breast implants
  • Pregnant or currently breastfeeding or nursing within the past 12 months
  • Prior invasive breast cancer within the past 5 years
  • Other invasive cancers greater than T1 stage (excluding non-melanoma skin) within the past 5 years
  • Pathogenic mutations in BRCA1, BRCA2, or PALB2
  • Type I or II diabetes requiring prescription medication
  • History of deep vein thrombosis, pulmonary embolus, or stroke
  • Chronic liver disease including nonalcoholic steatohepatitis and chronic hepatitis B or C
  • HIV infection
  • Current use of prescription anticoagulants such as warfarin or direct oral anticoagulants
  • Inability or unwillingness to stop daily aspirin use at least 3 weeks before fine needle aspiration
  • Starting or stopping oral contraceptives or hormonal progestin IUDs within 8 weeks of baseline fine needle aspiration
  • Use of progesterone/progestin injections or implants within 8 weeks prior
  • Current use of other investigational agents
  • Prior use of acolbifene or tamoxifen for more than 2 months
  • Use of prescription immunosuppressive drugs
  • History of allergic reactions to tamoxifen, acolbifene, or similar compounds
  • Uncontrolled illness including infections, heart failure, unstable angina, cardiac arrhythmia, or psychiatric/social conditions limiting study compliance

AI-Screening

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Trial Site Locations

Total: 4 locations

1

City of Hope Comprehensive Cancer Center

Duarte, California, United States, 91010

Actively Recruiting

2

Northwestern University

Chicago, Illinois, United States, 60611

Actively Recruiting

3

University of Kansas Cancer Center

Kansas City, Kansas, United States, 66160

Actively Recruiting

4

Ohio State University Comprehensive Cancer Center

Columbus, Ohio, United States, 43210

Actively Recruiting

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How is the study designed?

Study Type

INTERVENTIONAL

Masking

DOUBLE

Allocation

RANDOMIZED

Model

PARALLEL

Primary Purpose

PREVENTION

Number of Arms

2

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