Pathologic Complete Response (pCR) Rate and Predictors of Response to Taxane, Trastuzumab, and Pertuzumab in HER2‑Positive Breast Cancer: Secondary Analyses of EA1181/CompassHER2 pCR

Authors

• Nadine Tung, Beth Israel Deaconess Medical Center, Boston, MA
• Fengmin Zhao, ECOG-ACRIN Biostatistics Center, Malden, MA
• Angela DeMichele, University of Pennsylvania, Philadelphia, PA
• Aleix Prat, University of Barcelona, Barcelona, Spain
• Eric P. Winer, Yale Cancer Center, New Haven, CT
• Jean L. Wright, Lineberger Comprehensive Cancer Center, Chapel Hill, NC
• Abram Recht, Beth Israel Deaconess Medical Center, Boston, MA
• Anna C. Weiss, University of Rochester, Rochester, NY
• Judy A. Tjoe, Green Bay Oncology, Appleton, WI
• Sheldon M. Feldman, Montefiore Einstein Center for Cancer Care, Bronx, NY
• Gabrielle B. Rocque, O'Neal Comprehensive Cancer Center, Birmingham, AL.
• Mary Lou Smith, Research Advocacy Network, Naperville, IL
• Ciara C. O'Sullivan, Mayo Clinic, Rochester, MN
• Sagar D. Sardesai, The Ohio State University-James Comprehensive Cancer Center, Columbus, OH
• Shou-Ching Tang, LSU Health Sciences Center – New OrleansFollow
• Shanu Modi, Memorial Sloan Kettering Cancer Center, New York, NY
• William J. Irvin, Bon Secours Cancer Institute, Midlothian, VA
• Nisha Unni, University of Texas Southwestern Medical Center, Dallas, TX
• Chiara Battelli, New England Cancer Specialists, Scarborough, ME
• Nusayba Bagegni, Washington University, St Louis, MO
• Amy K. Krie, Allima Health Cancer Institute, Minneapolis, MN
• Mridula A. George, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ
• Melinda L. Telli, Stanford University School of Medicine, Stanford, CA
• Virginia F. Borges, University of Colorado Anschutz Medical Center, Aurora, CO
• Nina D'Abreo, NYU Langone Cancer Center, New York, NY
• Payal Shah, University of Pennsylvania, Philadelphia, PA
• Patricia Villagrasa, Reveal Genomics SL, Barcelona, Spain
• Sunil Badve, Emory University School of Medicine, Atlanta, GA
• Ann H. Partridge, Dana-Farber Cancer Institute, Boston, MA

Document Type

Article

Publication Date

8-20-2026

Publication Title

Journal of Clinical Oncology

Abstract

PURPOSE: EA1181 (ClinicalTrials.gov identifier: NCT04266249) is a single-arm trial evaluating neoadjuvant taxane, trastuzumab, and pertuzumab (THP) in patients with clinical stage II/IIIa human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This report focuses on the secondary end points of pathologic complete response (pCR) rates and associated factors. The primary end point-3-year recurrence-free survival among patients achieving a pCR (ypT0/Tis, ypN0)-will be reported when data mature.

METHODS: Patients received four cycles of trastuzumab and pertuzumab (HP) with either once per week paclitaxel (12 weeks) or docetaxel (every 3 weeks for four cycles), followed by surgery. Clinicopathologic characteristics were assessed in all patients. The HER2DX pCR score was determined using diagnostic biopsy samples in a representative subset. Logistic regression models identified factors associated with pCR.

RESULTS: A total of 2,175 patients were enrolled (781 HER2+/estrogen receptor‑negative [ER-]; 1,394 HER2+/ER+). Of 2,141 patients who initiated THP, the overall pCR rate was 43.8%: 63.7% in HER2+/ER- and 32.4% in HER2+/ER+ tumors. Higher pCR rates were observed in tumors that were ER-negative or low ER expressing, progesterone receptor-negative or low expressing, HER2 immunohistochemistry (IHC) 3+, and in patients treated with once per week paclitaxel. T3 disease was associated with a lower pCR rate in HER2+/ER- tumors; otherwise, tumor (T) and nodal (N) stage did not significantly affect pCR. Among 569 patients assessed for HER2DX pCR scores, a high score was independently associated with higher pCR rates, after adjustment for clinicopathologic variables.

CONCLUSION: Neoadjuvant THP achieved pCR in nearly two-thirds of patients with HER2+/ER- and one third with HER2+/ER+ breast cancer. Low hormone receptor expression, HER2 IHC 3+ status, once per week paclitaxel use, and a high HER2DX pCR score were independent predictors of pCR. These findings should help optimize risk stratification and treatment personalization for patients with HER2-positive breast cancer.

First Page

2919

Last Page

2928

PubMed ID

42623567

Volume

44

Issue

30

Rights

© 2026 by American Society of Clinical Oncology

Recommended Citation

Tung, Nadine; Zhao, Fengmin; DeMichele, Angela; Prat, Aleix; Winer, Eric P.; Wright, Jean L.; Recht, Abram; Weiss, Anna C.; Tjoe, Judy A.; Feldman, Sheldon M.; Rocque, Gabrielle B.; Smith, Mary Lou; O'Sullivan, Ciara C.; Sardesai, Sagar D.; Tang, Shou-Ching; Modi, Shanu; Irvin, William J.; Unni, Nisha; Battelli, Chiara; Bagegni, Nusayba; Krie, Amy K.; George, Mridula A.; Telli, Melinda L.; Borges, Virginia F.; D'Abreo, Nina; Shah, Payal; Villagrasa, Patricia; Badve, Sunil; and Partridge, Ann H., "Pathologic Complete Response (pCR) Rate and Predictors of Response to Taxane, Trastuzumab, and Pertuzumab in HER2‑Positive Breast Cancer: Secondary Analyses of EA1181/CompassHER2 pCR" (2026). School of Graduate Studies Faculty Publications. 680.
https://digitalscholar.lsuhsc.edu/sogs_facpubs/680
10.1200/JCO-25-02255