Preoperative Chemotherapy, Pembrolizumab and Low or High Dose RADiation in an Expansion Cohort of Node(+), Triple Negative Breast Cancer (P-RAD(+)TN-DCT)

This is a prospective radiation dose-finding, phase 2 expansion study of the Triple Negative (TN) cohort of the multicenter randomized study P-RAD (A Randomized Study of Preoperative Chemotherapy, Pembrolizumab and No, Low or High Dose RADiation in Node-Positive, HER2-Negative Breast Cancer; NCT04443348) that seeks to establish the optimal dose of radiation therapy (RT) to elicit an immune response when combined with immune checkpoint inhibitor (ICI) in breast cancer patients. Eligible subjects include women or men with operable, lymph node-positive, triple negative (TN) breast cancer who are candidates for standard of care neoadjuvant chemo-immunotherapy (NAC) based on the KEYNOTE-522 clinical trial. Thirty-two (n=32) patients will be randomized 1:1 to receive either low RT boost (9Gy total) or high RT boost (24Gy total). All RT will be delivered to the intact breast tumor in 3 daily fractions over 3 days.

In the Neoadjuvant Phase, the first cycle (C1) of pembrolizumab (200 mg i.v.) will be administered within 0-2 days of initiating RT. Participation in this study requires availability of residual diagnostic tissue biopsies of the primary tumor and metastatic lymph node for research use. If this tissue is not available, baseline research biopsies will be performed. Additionally, a research biopsy of the breast tumor and lymph node is required on Day 10-14 of C1 of pembrolizumab. After completion of the research biopsy in Week 2, the participants can commence standard-of-care neoadjuvant chemotherapy and pembrolizumab at the discretion of their medical oncology provider. After completing NAC, participants will undergo standard of care surgical resection of the breast and axillary lymph nodes, at the discretion of their surgical oncology provider. In the Adjuvant Phase, participants will receive standard of care adjuvant systemic therapy and standard of care adjuvant radiotherapy (if indicated), although recognizing that the breast tumor boost portion of this treatment has already been administered preoperatively. Except for late radiation adverse reactions of special interest, which will be followed yearly for up to 5 years, follow-up will occur every 6 months for 3 years.

Study Overview

• Status: Recruiting
• Conditions: Breast Cancer; Triple Negative Breast Cancer (TNBC); Node-positive Breast Cancer; HER2-Negative Breast Carcinoma
• Intervention / Treatment: Drug: Neoadjuvant Pembrolizumab; Radiation: low dose neoadjuvant boost; Radiation: High dose neoadjuvant boost

• Study Type: Interventional
• Enrollment (Estimated): 32
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Taylor Pierce; Phone Number: 919-984-0000; Email: Taylor_Pierce@med.unc.edu
• Study Contact Backup: Name: Emily L Schworer; Phone Number: 919-984-0000; Email: emily_lane@med.unc.edu

Study Locations

• United States
  • North Carolina
    • Chapel Hill, North Carolina, United States, 27599
      • Recruiting
      • University of North Carolina
      • Principal Investigator: Dana Casey, MD
      • Contact: Taylor Pierce; Phone Number: 984-974-0400; Email: Taylor_Pierce@med.unc.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

In order to participate in this study, a subject must meet all of the eligibility criteria outlined below.

• Written informed consent obtained to participate in the study and HIPAA authorization for release of personal health information. Subjects are willing and able
• to comply with study procedures based on the judgment of the investigator.
• Age ≥ 18 years at the time of consent.
• ECOG or Karnofsky Performance Status of 0 or 1

Exclusion Criteria:

• Active infection requiring systemic therapy.
• Pregnant or breastfeeding.
• Prior ipsilateral invasive breast, chest wall or thoracic radiotherapy
• Prior ipsilateral invasive breast cancer, contralateral breast cancer or a known
• additional, invasive malignancy that is progressing or required active treatment in
• the last 5 years

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: ARM 1; Participants will receive a low dose radiation therapy boost in 3 fractions (3Gy x 3 fraction = 9Gy total).	Drug: Neoadjuvant Pembrolizumab; 200 milligrams per square meter Neoadjuvant Pembrolizumab will be administered intravenously.; Radiation: low dose neoadjuvant boost; An external beam radiotherapy boost of 9Gy total will be administered over 3 fractions.
Experimental: ARM 2; Participants will receive a high dose radiation therapy boost in 3 fractions (8Gy x 3 fraction = 24Gy total).	Drug: Neoadjuvant Pembrolizumab; 200 milligrams per square meter Neoadjuvant Pembrolizumab will be administered intravenously.; Radiation: High dose neoadjuvant boost; An external beam radiotherapy boost of 24Gy total will be administered over 3 fractions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Nodal Pathologic Complete Response rate(pCR)	Nodal pCR is defined in a patient with no residual cancer cells in all sampled regional lymph nodes following completion of neoadjuvant systemic therapy as assessed by the study pathologist at the time of definitive surgery. Nodal pCR rates will be calculated and analyzed separately for patients receiving low versus high dose RT. A pooled analysis, incorporating the corresponding (3Gyx3 or 8Gyx3) patient cohort from the P-RAD trial, will be performed.	Time of surgery (24 week)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The CD3+/CD8+ T cell Breast post-treatment biopsy	The CD3+/CD8+ T cell Breast Immunoscore of post-treatment biopsy samples represents an average of percentage ranked scores for (i) CD3+ density in intra-tumoral region, (ii) CD3+ density in peri-tumoral region, (iii) CD8+ density in intra-tumoral region, and (iv) CD8+ density in peri-tumoral region. The reference cohort for determining percentage ranks will be the pre-treatment biopsy samples.	Time of surgery (24 week)
Composite pathologic complete response (pCR) (ypT0/Tis ypN0)	Composite pCR =T0/Tis and pN0 will be defined as the percentage of patients with Tis/T0 disease in the breast and no evidence of residual cancer cells in all sampled regional lymph nodes following completion of neoadjuvant systemic therapy, assessed by the study pathologist at the time of definitive surgery.	Time of surgery (24 week)
Total residual cancer burden (RCB)	RCB will be evaluated by the study pathologist and defined based on residual tumor size and/or area, overall cellularity, and extent of lymph node involvement.	Time of surgery (24 week)
Nodal pathologic complete response (pCR)	Nodal pCR is defined as absence of residual cancer cells in all sampled regional lymph nodes.	Time of surgery (24 week)
Composite pathologic complete response (pCR)	Composite pCR rate is measured by ypTis/T0 disease in the breast and the absence of residual cancer cells in all sampled regional lymph nodes.	Time of surgery (24 week)
Changes in pre- versus post-treatment intra-tumoral, peri-tumoral, and stromal CD3+ or CD8+ T cell percentages	Intra-tumoral, peri-tumoral, and stromal CD3+ and CD8+ T-cell densities will be measured in biopsy and surgical specimens and compared. Pan-cytokeratin staining will be used to identify tumor regions, and the percentages will be analyzed.	Time of surgery (24 week)
Change in tumor-infiltrating lymphocyte (TIL)	Tumor-infiltrating lymphocyte (TIL) counts will be assessed on hematoxylin and eosin (H&E)-stained biopsy and surgical specimens using the Salgado criteria, which evaluate the percentage of stromal area occupied by lymphocytes following standardized guidelines. The values in biopsy and surgical specimens and compared.	Time of surgery (24 week)
Change in Programmed cell death 1 ligand 1(PD-L1)	Changes in PD-L1 expression levels will be assessed using the U.S. FDA-approved 22C3 pharmDx companion diagnostic assay to determine the Combined Positive Score (CPS). A CPS greater than 1 will be considered PD-L1 positive. The values in biopsy and surgical specimens and compared.	Time of surgery (24 week)
Changes in intratumoral, peri-tumoral, and stromal CD4+Foxp3+ T regulatory cell densities	Changes in intratumoral, peri-tumoral, and stromal CD4+FOXP3+ regulatory T-cell densities will be quantified using quantitative immunofluorescence (QIF) for CD4 and FOXP3 in formalin-fixed, paraffin-embedded (FFPE) tumor biopsy and surgical specimens. Pan-cytokeratin staining will be used to identify tumor regions.	Time of surgery (24 week)
Adverse Events	Adverse events will be classified and graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0 (NCI-CTCAE v5.0), at 30 days after investigational pembrolizumab administration. The number of observed AEs will be reported.	Up to 60 weeks
Invasive disease-free survival (iDFS)	iDFS will be defined as the time from completion of surgery to the first occurrence of the following events: invasive ipsilateral, local, regional, or distant recurrence, or death due to breast cancer.	Up to 5 years
Event-free survival (EFS)	EFS will be defined as the time from the initiation of the study treatment to any of the following events: progression of disease (precluding surgery), recurrence (local or distant), or death due to any cause.	Up to 5 years
Quality of life Global Health PROMIS in Low Dose Radiotherapy Boost Group	Quality of life will be assessed by Patient-Reported Outcomes Measurement Information System (PROMIS) tool developed by the National Institutes of Health (NIH) before and after treatment. It is designed to measure a patient's overall physical, mental, and social health using a brief and standardized questionnaire. Responses are collected using a 5-point Likert scale (1 = Poor, 5 = Excellent), summed into raw scores, and converted to standardized T-scores (mean = 50, SD = 10; range ~20-80), with higher scores indicating better health.	Baseline, Week 2, Week 8, Week 14, and Week 20, 6 months post-surgery, and monthly for up to 3 years
Quality of life BREAST-Q in Low Dose Radiotherapy Boost Group	Patient-reported outcomes related to breast surgery will be assessed using the BREAST-Q questionnaire, a validated instrument measuring satisfaction with breasts, psychosocial well-being, physical well-being, and sexual well-being. Most items are answered on a 4- to 5-point Likert scale, for example: Satisfaction: "Very dissatisfied" → "Very satisfied" or Frequency/impact: "Never" → "Always" or "Not at all" → "Very much. "Responses are scored according to the BREAST-Q scoring system and transformed to a 0-100 scale, with higher scores indicating greater satisfaction or better quality of life.	Baseline, Week 2, Week 8, Week 14, and Week 20, 6 months post-surgery, and monthly for up to 3 years
The Was It Worth It (WIWI) in Low Dose Radiotherapy Boost Group	The Was It Worth It (WIWI) instrument, also called the Trial Satisfaction survey, is a validated patient-reported outcome measure designed to assess participants' experiences and satisfaction with clinical trial participation. It evaluates whether patients feel that joining the trial was worthwhile and captures their overall perception of the trial experience. Responses are collected using a Likert-type scale (3 to 5 points) or categorical options, with higher scores indicating a more positive perception of trial participation. Scores will be summarized to assess overall patient satisfaction and the perceived value of trial involvement.	Baseline, Week 2, Week 8, Week 14, and Week 20, 6 months post-surgery, and monthly for up to 3 years
Quality of life Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) in Low Dose Radiotherapy Boost Group	PRO-CTCAE, which collects information on the frequency, severity, interference, and presence or absence of symptoms such as pain, fatigue, nausea, and cutaneous side effects including rash and hand-foot syndrome. These toxicities are selected because they can be meaningfully reported from the patient perspective. PRO-CTCAE responses are scored from 0 to 4, or 0/1 for absent/present items. If the first response in an item set is the lowest on the scale (e.g., 'Never' for frequency or 'None' for severity), any conditionally branched items are scored as 0 and not treated as missing.	Baseline, Week 2, Week 8, Week 14, and Week 20, 6 months post-surgery, and monthly for up to 3 years
Comparison tumor-infiltrating lymphocyte (TIL)	Differences in tumor-infiltrating lymphocyte (TIL) between low and high dose levels will be assessed by hematoxylin and eosin (H&E)-stained biopsy and surgical specimens using the Salgado criteria, which evaluate the percentage of stromal area occupied by lymphocytes following standardized guidelines. The values in biopsy and surgical specimens and compared. Differences in TIL between low and high dose levels (3Gyx3 or 8Gyx3) will be assessed by H&E.	Time of surgery (24 week)

Collaborators and Investigators

• Sponsor: UNC Lineberger Comprehensive Cancer Center
• Collaborators: National Cancer Institute (NCI); Merck Sharp & Dohme LLC
• Investigators: Principal Investigator: Dana Casey, MD, UNC Lineberger Comprehensive Cancer Center

Publications and helpful links

Helpful Links

• University of North Carolina Lineberger Comprehensive Cancer Center Clinical Trials

Study record dates

Study Major Dates

• Study Start (Actual): March 17, 2026
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): January 1, 2032

Study Registration Dates

• First Submitted: December 1, 2025
• First Submitted That Met QC Criteria: December 1, 2025
• First Posted (Actual): December 11, 2025

Study Record Updates

• Last Update Posted (Actual): April 27, 2026
• Last Update Submitted That Met QC Criteria: April 24, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: neoadjuvant treatment; radiation therapy; pembrolizumab; immune checkpoint inhibitor; radiotherapy boost
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; Triple Negative Breast Neoplasms
• Other Study ID Numbers: LCCC2426-DCT; R01CA274254 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No