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OncoMatch/Clinical Trials/NCT03804944

Converting HR+ Breast Cancer Into an Individualized Vaccine

Is NCT03804944 recruiting? Yes, currently enrolling (Jun 2026). This Phase 2 trial studies multiple treatments including CDX-301 and Pembrolizumab (200mg IV for 30 minutes for breast cancer.

Phase 2RecruitingWeill Medical College of Cornell UniversityNCT03804944Data as of Jun 2026

Treatment: Pembrolizumab (200mg IV for 30 minutes · CDX-301Newly diagnosed post-menopausal women with clinical stage II-III, HR+HER2- breast cancer are eligible to a randomized trial, concurrently open at five US academic institutions. Patients receiving 4 months of standard neoadjuvant hormonal therapy with letrozole are randomly assigned to one of 4 arms of a trial testing focal hypo-fractionated RT alone or with immunotherapy combinations.

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Extracted eligibility criteria

Treatments studied

Immunotherapy

Pembrolizumab (200mg IV for 30 minutes

Other

CDX-301

Cancer type

Breast Carcinoma

Biomarker criteria

Required: HER2 (ERBB2) negative

Required: ESR1 positive

Required: PR (PGR) positive or negative

Disease stage

Required: Stage I (>1.5CM, IF N0), II, III (AJCC 8th edition)

Clinical stage I(>1.5cm, if N0) - III breast cancer, as per AJCC staging 8th edition.

Performance status

ECOG 0–1(Restricted strenuous activity)

Demographics

Ages ≤ 90
Female only

Prior therapy

Cannot have received: systemic chemotherapy

Current use of systemic chemotherapy

Cannot have received: endocrine therapy

Current use of endoctine therap

Cannot have received: HER2-targeted therapy

Current use of HER2-neu targeted therapy

Cannot have received: anti-PD-1/PD-L1/PD-L2 or co-inhibitory T-cell receptor therapy

Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (eg, CTLA-4, OX-40, CD137).

Cannot have received: radiation therapy

Previous radiotherapy of the same breast.

Cannot have received: live vaccine

Has received a live vaccine within 30 days prior to the first dose of study drug.

Lab requirements

Blood counts

WBC ≥ 2000/uL Absolute neutrophil count (ANC) ≥1500/μL Platelets ≥100 000/μL Hemoglobin ≥9.0 g/dL or ≥5.6 mmol/La

Kidney function

Creatinine OR Measured or calculated creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤1.5 × ULN OR ≥30 mL/min for participant with creatinine levels >1.5 × institutional ULN

Liver function

Total bilirubin ≤1.5 ×ULN OR direct bilirubin ≤ULN for participants with total bilirubin levels >1.5 × ULN; AST (SGOT) and ALT (SGPT) ≤2.5 × ULN (≤5 × ULN for participants with liver metastases)

Adequate bone marrow reserve and liver function: WBC ≥ 2000/uL Absolute neutrophil count (ANC) ≥1500/μL Platelets ≥100 000/μL Hemoglobin ≥9.0 g/dL or ≥5.6 mmol/La Creatinine OR Measured or calculated creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤1.5 × ULN OR ≥30 mL/min for participant with creatinine levels >1.5 × institutional ULN Total bilirubin ≤1.5 ×ULN OR direct bilirubin ≤ULN for participants with total bilirubin levels >1.5 × ULN AST (SGOT) and ALT (SGPT) ≤2.5 × ULN (≤5 × ULN for participants with liver metastases) International normalized ratio (INR) OR prothrombin time (PT) Activated partial thromboplastin time (aPTT) ≤1.5 × ULN unless participant is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants

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

US trial sites

  • Cedars-Sinai Medical Center · Los Angeles, California
  • Icahn School of Medicine at Mt Sinai · New York, New York
  • New York Presbyterian Hospital - Queens · New York, New York
  • Weill Cornell Medicine New York Presbyterian Hospital · New York, New York
  • Brooklyn Methodist Hospital - NewYork Presbyterian · New York, New York

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See all sites on ClinicalTrials.gov →

Frequently asked questions

Is NCT03804944 currently recruiting?

Yes, this trial is currently recruiting patients.

Are there prior therapy exclusions?

Yes. Prior systemic chemotherapy, endocrine therapy, HER2-targeted therapy disqualifies patients from enrollment.

Does this trial require ERBB2?

Yes, ERBB2 negative is a required biomarker for enrollment.

Does this trial require ESR1?

Yes, ESR1 positive is a required biomarker for enrollment.

Does this trial require PGR?

Yes, PGR positive or negative is a required biomarker for enrollment.

What disease stage is eligible?

Stage I (>1.5CM, IF N0) or II or III is required.

Is there an age limit?

Yes. Patients must be 90 years or younger.

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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