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OncoMatch/Clinical Trials/NCT05900895

Estradiol Plus Olaparib for Breast Cancer (PHOEBE)

Is NCT05900895 recruiting? Yes, currently enrolling (Jun 2026). This Phase 1 trial studies multiple treatments including Olaparib and 17b-estradiol for metastatic breast cancer.

Phase 1RecruitingMary D ChamberlinNCT05900895Data as of Jun 2026

Treatment: Olaparib · 17b-estradiolDetermine the safety and recommended Phase II dose of olaparib in combination with 17b-estradiol in post-menopausal patients with advanced ER+/HER2- breast cancer.

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Extracted eligibility criteria

Treatments studied

Targeted therapy

Olaparib

Other

17b-estradiol

Cancer type

Breast Carcinoma

Biomarker criteria

Required: ESR1 overexpression (ER+)

ER+

Required: HER2 (ERBB2) wild-type (HER2-)

HER2-

Disease stage

Metastatic disease required

Demographics

Female only

Prior therapy

Min 1 prior line

Must have received: endocrine-based therapy — advanced/metastatic

Received ≥1 prior line of endocrine-based therapy in the advanced/metastatic setting

Cannot have received: systemic chemotherapy

Exception: within the last 3 weeks

Any investigational cancer therapy or systemic chemotherapy in the last 3 weeks

Cannot have received: radiation therapy

Exception: within the last 2 weeks

Any radiation therapy in the last 2 weeks

Lab requirements

Kidney function

creatinine clearance > 30 ml/min

Structured fields extracted by AI. May contain errors — verify against the official protocol.

US trial sites

  • Dartmouth Cancer Center · Lebanon, New Hampshire

Showing up to 5 US sites.

See all sites on ClinicalTrials.gov →

Frequently asked questions

Is NCT05900895 currently recruiting?

Yes, this trial is currently recruiting patients.

Are there prior therapy exclusions?

Yes. Prior systemic chemotherapy, radiation therapy disqualifies patients from enrollment.

Does this trial require ESR1?

Yes, ESR1 overexpression is a required biomarker for enrollment.

Does this trial require ERBB2?

Yes, ERBB2 wild-type is a required biomarker for enrollment.

Is this trial open to male patients?

No. This trial enrolls female patients only.

Could you qualify for this trial?

Enter your biomarker results to see how this trial's eligibility criteria match your specific cancer profile.

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