A Phase 3 interventional study of Pembrolizumab and Patient Observation in Anatomic Stage II Breast Cancer AJCC v8, Early Stage Triple-Negative Breast Carcinoma and Anatomic Stage IIIA Breast Cancer AJCC v8, sponsored by Alliance for Clinical Trials in Oncology. Recruiting at 846 sites in 3 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-05.
Sponsored by Alliance for Clinical Trials in Oncology · Phase 3, Interventional, and Treatment
This phase III trial compares the effect of continuation of treatment with pembrolizumab (usual approach) to observation only at preventing cancer from coming back in patients with early-stage triple-negative breast cancer (TNBC) who achieved a pathologic complete response after preoperative chemotherapy in combination with pembrolizumab. The usual approach for patients with early-stage TNBC who receive preoperative chemotherapy plus pembrolizumab is to continue to receive pembrolizumab for up to 27 weeks after surgery. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. This trial may help researchers determine if observation is as good as receiving pembrolizumab for 27 weeks after surgery in triple-negative breast cancer patients who achieved a pathologic complete response after preoperative treatment with chemotherapy and pembrolizumab.
PRIMARY OBJECTIVES:
I. To evaluate whether observation results in a non-inferior recurrence-free survival (RFS) compared to adjuvant pembrolizumab in early-stage triple-negative breast cancer (TNBC) patients who achieve a pathologic complete response (pCR) after neoadjuvant chemotherapy with pembrolizumab.
II. To compare quality of life (QOL) at approximately 27 weeks as assessed by the Functional Assessment of Cancer Therapy-Breast (FACT-B) Trial Outcome Index between patients randomized to adjuvant pembrolizumab versus observation. (Quality of Life) III. To assess the social value of de-escalation of adjuvant breast cancer immunotherapy at approximately 27 weeks and, by modeling, over a lifetime. (Value of Care)
SECONDARY OBJECTIVES:
I. To evaluate whether observation compared to adjuvant pembrolizumab impacts the following:
Ia. RFS by stage at presentation and by receipt of prior anthracycline therapy; Ib. Adverse event rate: difference in Grade 3 or higher adverse event rates overall and Grade 3 or higher immune-related adverse events (irAEs) rates; Ic. Overall Survival (OS); Id. Locoregional recurrence (LRR both isolated LRR as first events and LRR events simultaneous with distant metastases [DM]); Ie. RFS, LRR, OS, adverse events, and QOL by age (=\< 45, 46-65, and > 65), race, and ethnicity; If. Adverse events related to receipt of radiotherapy. II. To assess the value of de-escalation of breast cancer immunotherapy from the payer perspective at approximately 27 weeks and, by modelling, over a lifetime. (Value of Care) III. To compare patient out-of-pocket costs at approximately 27 weeks between patients randomized to adjuvant pembrolizumab versus observation. (Value of Care) IV. To compare financial toxicity at approximately 27 weeks between patients randomized to adjuvant pembrolizumab versus observation. (Value of Care) V. To compare work/productivity impairment at approximately 27 weeks between patients randomized to adjuvant pembrolizumab versus observation. (Value of Care)
EXPLORATORY OBJECTIVES:
I. To describe trajectories of QOL over time among patients randomized to adjuvant pembrolizumab versus (vs.) observation. (Quality of Life) II. To compare various QOL domains after approximately 27 weeks as assessed by the 5 subscales of the FACT-B Index between patients randomized to adjuvant pembrolizumab versus observation. (Quality of Life) III. To compare self-reported symptomatic adverse events at approximately 27 weeks assessed by the patient reported outcome Common Terminology Criteria for Adverse Events (PRO-CTCAE) between patients randomized to adjuvant pembrolizumab versus observation. (Quality of Life) IV. To describe trajectories of financial toxicity and work/productivity impairment over time from baseline to approximately 27 weeks among patients randomized to adjuvant pembrolizumab versus observation. (Value of Care) V. To develop and assess a measure of value from the patient perspective at approximately 27 weeks. (Value of Care)
OUTLINE: Patients are randomized to 1 of 2 arms after completing neoadjuvant chemotherapy in combination with pembrolizumab, followed by definitive breast surgery.
ARM I (PEMBROLIZUMAB): Patients receive pembrolizumab intravenously (IV) over 25-40 minutes once every 3 weeks (Q3W) or once every 6 weeks (Q6W) for 27 weeks. Patients also undergo tumor biopsy and collection of blood throughout the study. Patients also undergo mammography, breast ultrasound or magnetic resonance imaging (MRI) during follow-up.
ARM II (OBSERVATION): Patients undergo observation for 27 weeks. Patients also undergo tumor biopsy and collection of blood throughout the study. Patients also undergo mammography, breast ultrasound or MRI during follow-up.
Alliance for Clinical Trials in Oncology is the lead sponsor of 499 studies on the registry; 27 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 6 (100%) have results posted.
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Triple Negative Breast Cancer:
An interval of no more than 12 weeks between the completion date of the final surgery and the date of randomization
* Note: Adjuvant radiation can be given on study, however, it is recommended to complete adjuvant radiation prior to registration. If radiation is given on study, it is encouraged to be given concurrently with pembrolizumab if the patient is on the pembrolizumab arm, per investigator discretion. Treatment with adjuvant pembrolizumab is strongly discouraged prior to participation in this trial, but if administered (e.g., if patients are awaiting pathology results), pembrolizumab may be administered for up to 6 weeks (i.e., up to 2 q3week doses or up to one q6week dose) post-surgery and must be completed prior to registration post-surgery and must be completed prior to registration
Adequate excision: Surgical removal of all clinically evident disease in the breast and lymph nodes as follows:
Breast surgery: Total mastectomy or breast-conserving surgery with histologically negative margins, including no ink on tumor for DCIS, at the time of excision
** For patients who undergo breast-conserving surgery, the margins of the resected specimen must be histologically free of ductal carcinoma in-situ (DCIS) as determined by the local pathologist. If pathologic examination demonstrates DCIS at the line of resection, additional operative procedures may be performed to obtain clear margins. If DCIS is still present at the resected margin after re-excision(s), the patient must undergo total mastectomy to be eligible. Patients with margins positive for classic lobular carcinoma in situ (LCIS) are eligible without additional resection
Lymph node surgery:
For a patient with clinically N1 disease at diagnosis (with positive results from a fine-needle aspiration, core biopsy, or sentinel node biopsy performed prior to preoperative therapy) additional surgical evaluation of the axilla following preoperative therapy is required
*** If they become cN0 (no palpable adenopathy), then a sentinel lymph node biopsy could have been performed at time of surgery (axillary dissection would also be permitted); if the sentinel lymph node biopsy is positive, the patient is no longer eligible
Total Bilirubin =\<1.5 x upper limit of normal (ULN)
* Patients with Gilbert's disease with a total bilirubin =\< 2.5 x ULN and direct bilirubin within normal limits are permitted
Exclusion Criteria:
No history of intolerance, including Grade 3 or 4 infusion reaction or hypersensitivity to pembrolizumab or murine proteins or any components of the product
* Note: Prior immune-related adverse events (irAEs) are allowed if they resolved to ≤ grade 1 and the patient tolerated subsequent therapy without requiring chronic steroids for the irAE. The following are exceptions to this criterion: Grade 2 or lower immune mediated endocrinopathies due to neoadjuvant checkpoint inhibition but patients are stable on endocrine therapy and were able to continue checkpoint inhibition.
Patients receive pembrolizumab IV over 25-40 minutes Q3W or Q6W for 27 weeks. Patients also undergo tumor biopsy and collection of blood throughout the study. Patients also undergo mammography, breast ultrasound or MRI and during follow-up.
Biological: Pembrolizumab · Procedure: Biopsy · Procedure: Biospecimen Collection · Other: Questionnaire Administration · Other: Quality-of-Life Assessment
Patients undergo observation for 27 weeks. Patients also undergo tumor biopsy and collection of blood throughout the study. Patients also undergo mammography, breast ultrasound or MRI during follow-up.
Other: Patient Observation · Procedure: Biopsy · Procedure: Biospecimen Collection · Other: Questionnaire Administration · Other: Quality-of-Life Assessment
Given IV
Also known as: Keytruda
Undergo observation
Also known as: Active surveillance, watchful waiting, observation
Undergo biopsy
Undergo collection of blood
Ancillary studies
Ancillary studies
Recurrence-free survival (RFS)
Defined as the time from randomization to first invasive local, regional, or distant recurrence or death due to any cause. RFS will be compared between treatment arms using the hazard ratio (with 90% confidence interval and stratified log-rank test) from a stratified Cox model.
Time frame: Up to 10 years.
Incidence of adverse events (AEs)
Adverse events will be determined using the latest version of the Common Terminology Criteria for Adverse Events (CTCAE). The proportions of patients with a grade 3 or higher AE will be compared between the arms using a chi-square test. A similar analysis will be done to compare the grade 3 or higher irAE rates
Time frame: Up to 27 weeks after registration
Overall survival
Defined as the time from randomization to death due to any cause. OS will be compared between treatment arms using the hazard ratio (and stratified log-rank test) from a stratified Cox model
Time frame: Up to 10 years.
Locoregional recurrence incidence
Defined as the time from randomization to first invasive local or regional recurrence. The cumulative incidence of LRR will be compared between treatment arms using a log-rank test (and estimated using Kaplan-Meier curves).
Time frame: Up to 10 years.
Radiation adverse events
Radiation adverse events include pneumonitis, hypothyroidism and dermatitis. Radiation AE event rates will be determined for patients who received radiation. The numerator is the number of patients with the radiation AE and the denominator is the number of patients who received radiation. The analysis of the radiation related adverse event rates will only include patients who received radiation treatment. The radiation AE rates will be compared between the two arms using a chi-square test.
Time frame: Up to 27 weeks after registration
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Alliance for Clinical Trials in Oncology