32 Neoadjuvant Pembrolizumab or Placebo Plus Chemotherapy Followed by Adjuvant Pembrolizumab or Placebo for Early-Stage Triple- Negative Breast Cancer: Updated Event-Free Survival Results From the Phase 3 KEYNOTE-522 Study

Publication
Article
Miami Breast Cancer Conference® Abstracts Supplement41st Annual Miami Breast Cancer Conference® - Abstracts
Volume 38
Issue 4
Pages: 36-37

Background

In KEYNOTE-522, neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab showed statistically significant and clinically meaningful improvements in pathological complete response (pCR) and event-free survival (EFS) compared with neoadjuvant placebo plus chemotherapy followed by adjuvant placebo in patients with early-stage triple-negative breast cancer (TNBC). Here, we present updated EFS results after a median follow-up of about 5 years.

Methods

Eligible patients with previously untreated, nonmetastatic, centrally confirmed TNBC (stage T1c N1-2 or T2-4 N0-2 per American Joint Committee on Cancer) were randomly assigned 2:1 to neoadjuvant pembrolizumab at 200 mg every 3 weeks or placebo, both given with 4 cycles of paclitaxel plus carboplatin, then with 4 cycles of doxorubicin or epirubicin plus cyclophosphamide. After definitive surgery, patients received adjuvant pembrolizumab or placebo for 9 cycles or until recurrence or unacceptable toxicity. Dual primary end points were pCR (ypT0/Tis ypN0) and EFS (time from randomization to disease progression that precluded definitive surgery, local/distant recurrence, second primary cancer, or death from any cause).

Results

    EFS Results in the Overall Population and by Subgroup Pembrolizumab plus Chemotherapy

EFS Results in the Overall Population and by Subgroup Pembrolizumab plus Chemotherapy

A total of 1174 patients were randomly assigned to pembrolizumab (n = 784) or placebo (n = 390). At the data cutoff (March 23, 2023), the median follow-up was 63.1 months. Additionally, 145 patients (18.5%) in the pembrolizumab group and 108 patients (27.7%) in the placebo group had an EFS event (HR, 0.63; 95% CI, 0.49-0.81). The 60-month EFS rate was 81.3% (95% CI, 78.4-83.9) vs 72.3% (95% CI, 67.5-76.5), respectively; the median was not reached in either group. The benefit of neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab
vs neoadjuvant chemotherapy alone was consistent with the primary EFS results in all 5 sensitivity analyses, showing durable and robust EFS benefit in the pembrolizumab arm. The EFS benefit with pembrolizumab was consistent across prespecified subgroups, including PD-L1 expression, nodal status, disease stage, menopausal status, HER2 status, and lactate dehydrogenase level (Table). In a prespecified, nonrandomized, exploratory analysis, 5-year EFS rates in the pembrolizumab and placebo groups were 92.2% vs 88.2% in patients with a pCR, and 62.6% vs 52.3% in patients without a pCR. Additional analyses will be included in the presentation. Follow-up for overall survival is ongoing.

Conclusions

Neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab continues to show a clinically meaningful improvement in EFS compared with neoadjuvant chemotherapy alone in patients with early-stage TNBC. This is seen across subgroups and regardless of the pCR outcome.

Articles in this issue

31 Adjuvant Abemaciclib Plus Endocrine Therapy for HR+, HER2–, High-Risk Early Breast Cancer: Results From a Preplanned MonarchE Overall Survival Interim Analysis, Including 5-Year Efficacy Outcomes
31 Adjuvant Abemaciclib Plus Endocrine Therapy for HR+, HER2–, High-Risk Early Breast Cancer: Results From a Preplanned MonarchE Overall Survival Interim Analysis, Including 5-Year Efficacy Outcomes
32 Neoadjuvant Pembrolizumab or Placebo Plus Chemotherapy Followed by Adjuvant Pembrolizumab or Placebo for Early-Stage Triple- Negative Breast Cancer: Updated Event-Free Survival Results From the Phase 3 KEYNOTE-522 Study
32 Neoadjuvant Pembrolizumab or Placebo Plus Chemotherapy Followed by Adjuvant Pembrolizumab or Placebo for Early-Stage Triple- Negative Breast Cancer: Updated Event-Free Survival Results From the Phase 3 KEYNOTE-522 Study
33 MammaPrint® and BluePrint® Predict Anthracycline Chemosensitivity in Patients With HR+HER2– Early-Stage Breast Cancer Enrolled in FLEX
33 MammaPrint® and BluePrint® Predict Anthracycline Chemosensitivity in Patients With HR+HER2– Early-Stage Breast Cancer Enrolled in FLEX
34 How Mobile Computing Devices Offer Support for Classic and Molecular Multidisciplinary and Tumor Boards
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35 Impact of Comorbidities on Real-World (rw) Clinical Outcomes of Patients (pts) With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2–Negative (HR+/HER2–) Advanced Breast Cancer (ABC) Treated With Palbociclib (PAL) and Enrolled in POLARIS
35 Impact of Comorbidities on Real-World (rw) Clinical Outcomes of Patients (pts) With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2–Negative (HR+/HER2–) Advanced Breast Cancer (ABC) Treated With Palbociclib (PAL) and Enrolled in POLARIS
36 MONARCH 3: Final Overall Survival Results of Abemaciclib Plus a Nonsteroidal Aromatase Inhibitor as First-Line Therapy for HR+/HER2– Advanced Breast Cancer
36 MONARCH 3: Final Overall Survival Results of Abemaciclib Plus a Nonsteroidal Aromatase Inhibitor as First-Line Therapy for HR+/HER2– Advanced Breast Cancer
37 Estimating the Direct and Indirect Resource Burden of Treatment Management With Current Standard of Care or Elacestrant for ER+, HER2–, ESR1-Mutated Advanced or Metastatic Breast Cancer Patients: A Population- Level Provider Model
37 Estimating the Direct and Indirect Resource Burden of Treatment Management With Current Standard of Care or Elacestrant for ER+, HER2–, ESR1-Mutated Advanced or Metastatic Breast Cancer Patients: A Population- Level Provider Model
38 Influence of Race on Attainment of Textbook Oncologic Outcome Following Modified Radical Mastectomy for Breast Cancer
38 Influence of Race on Attainment of Textbook Oncologic Outcome Following Modified Radical Mastectomy for Breast Cancer
39 The Influence of Reconstruction Type on Outcomes in Women Undergoing Mastectomy With Immediate Reconstruction:  A Nationwide Study
39 The Influence of Reconstruction Type on Outcomes in Women Undergoing Mastectomy With Immediate Reconstruction: A Nationwide Study
40 Ethnic Disparities in Complication Rates and Outcomes  of Nipple-Sparing Mastectomy:  A Comprehensive Analysis
40 Ethnic Disparities in Complication Rates and Outcomes of Nipple-Sparing Mastectomy: A Comprehensive Analysis
41 A Case Series of Sarcomas
41 A Case Series of Sarcomas
42 Transitional Lymphedema: Understanding the Temporal Dynamics Post-Axillary Surgery
42 Transitional Lymphedema: Understanding the Temporal Dynamics Post-Axillary Surgery
43 Impact of Lymphatic Microsurgical Preventing Healing Approach (LYMPHA) on Postoperative Complication Rates in Mastectomy With Immediate Prosthetic-Based Breast Reconstruction
43 Impact of Lymphatic Microsurgical Preventing Healing Approach (LYMPHA) on Postoperative Complication Rates in Mastectomy With Immediate Prosthetic-Based Breast Reconstruction
44 Variant of Uncertain Significance (VUS) Genetic Testing Results and Mastectomy Choice in Lumpectomy-Eligible Patients
44 Variant of Uncertain Significance (VUS) Genetic Testing Results and Mastectomy Choice in Lumpectomy-Eligible Patients
45 Application of the 7-Gene Biosignature in Palpable Versus Nonpalpable Ductal Carcinoma In Situ in a Black Patient Population: Does Palpability Suggest a More Aggressive Genomic Risk?
45 Application of the 7-Gene Biosignature in Palpable Versus Nonpalpable Ductal Carcinoma In Situ in a Black Patient Population: Does Palpability Suggest a More Aggressive Genomic Risk?
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