De-escalated neoadjuvant pertuzumab+trastuzumab with or without paclitaxel weekly in HR-/HER2+ early breast cancer: ADAPT-HR-/HER2+ biomarker and survival results.

Authors

Nadia Harbeck

Nadia Harbeck

Breast Center, Dept. Obstetrics & Gynecology, University of Munich (LMU) and CCCLMU and West German Study Group, Munich, Germany

Nadia Harbeck , Oleg Gluz , Matthias Christgen , Sherko Kuemmel , Eva-Maria Grischke , Michael Braun , Jochem Potenberg , Katja Krauss , Claudia Schumacher , Helmut Forstbauer , Toralf Reimer , Andrea Stefek , Hans Holger Fischer , Enrico Pelz , Monika Graeser , Christine zu Eulenburg , Ronald E. Kates , Rachel Wuerstlein , Hans Heinrich Kreipe , Ulrike Nitz

Organizations

Breast Center, Dept. Obstetrics & Gynecology, University of Munich (LMU) and CCCLMU and West German Study Group, Munich, Germany, West German Study Group and Ev. Hospital Bethesda, Breast Center Niederrhein, Moenchengladbach, Germany and University Hospital Cologne, Cologne, Germany, Medical School Hannover, Institute of Pathology, Hannover, Germany, Breast Center, Ev. Clinics Essen-Mitte and Women’s Clinic, Charité Berlin and West German Study Group, Essen, Germany, Universitӓts-Frauenklinik Tuebingen, Eberhard Karls University, Tuebingen, Germany, Interdisciplinary Breast Center, Rotkreuz-Clinics Munich, Munich, Germany, Ev. Waldkrankenhaus, Berlin, Germany, Breast Center, Dept. Obstetrics & Gynecology, RWTH Aachen, Aachen, Germany, St. Elisabeth Hospital Köln-Hohenlind, Cologne, Germany, Praxisnetzwerk Hämatologie/intern. Onkologie, Troisdorf, Germany, University Hospital Gynecology and Policlinic Rostock, Rostock, Germany, Johanniter KH Stendal, Stendal, Germany, Evangelische Kliniken Gelsenkirchen, Germany, Gelsenkirchen, Germany, Institute for Pathology, Viersen, Germany, Breast Center Niederrhein, Ev. Bethesda Hospital and Department of Gynecology, University Medical Center Hamburg and West German Study Group, Mönchengladbach, Germany, West German Study Group, Mönchengladbach, Germany, Breast Center, Dept. OB&GYN, University of Munich (LMU) and CCCLMU, West German Study Group, Munich, Germany, Hanover Medical School, Institute of Pathology, Hannover, Germany, West German Study Group/Breast Center Niederrhein, Mönchengladbach, Germany

Research Funding

Pharmaceutical/Biotech Company
Roche, AOK.

Background: Optimal use of de-escalated, particularly chemotherapy(CT)-free, neoadjuvant regimens in HER2+ early breast cancer (EBC) is currently unclear as there are limited survival data so far. In ADAPT-HR-/HER2+, we previously showed an excellent pCR rate of 90% after 12-week neoadjuvant paclitaxel (Pac) +pertuzumab (P) +trastuzumab (T) and a substantial and clinically meaningful pCR rate of 34% after P+T alone in HR-/HER2+ EBC. Here, we present first survival data. Methods: The prospective multicenter WSG-ADAPT-HR-/HER2+ phase II-trial is part of the ADAPT-umbrella protocol. Patients with cT1-cT4c, cN0-3 HR-/HER2+ EBC (n = 134) were randomized to 4 cycles of P+T +/- pac d1,8,15 q3w. All tumors were HR-negative (ER and PR < 1%) and HER2-positive (central lab, i.e., 2+ FISH positive or 3+ by immunohistochemistry. Primary endpoint was pCR (ypT0/is/ypN0); omission of further CT was allowed in pts with pCR. Trial objective was to compare pCR in P+T+pac arm vs. early responders in P+T arm (defined as low cellularity and/or Ki67 decrease >30% after 3 weeks). The trial was stopped early due to the observed pCR superiority in the P+T+pac arm. Secondary endpoints included safety, 5-y (distant)-DFS, OS and translational research. Cox-regression analysis was applied. PAM50 subtype was assessed using the BC360 panel. Results: 134 patients were randomized to P+T (n = 92) or P+T+pac (n = 42). 60% of tumors were cT2-4, 42% clinically node-positive. After a median follow-up of 5 years, no significant differences between study arms were observed regarding DFS, dDFS, and OS; only 13 iDFS events (7 dDFS) were observed in the whole ITT population. pCR (vs. non-pCR) after the 12-week study treatment (irrespective of study arm) was strongly associated with improved iDFS (5y DFS 98.5% vs. 82%, HR = 0.14, 95% CI 0.03-0.64). Of the 69 patients with pCR, 39 (56.5%) received no further CT (P+T arm: n = 9, 29% vs. (P+T+pac arm n = 30, 79%); only 1 distant relapse (1.4%) was observed in these patients. In the CT-free P+T arm, no pCR was observed in patients with low HER2 expression (IHC 1+/2+ and FISH positive) and/or basal-like subtype by PAM50 (n = 17, 19%). In the total study population, low HER2 expression and/or no early response was strongly associated with worse dDFS (p =.029) and iDFS (p =.068). No new safety signals were observed. Conclusions: For the first time, we have shown both excellent pCR and survival in patients treated by de-escalated neoadjuvant CT+P+T irrespective of further CT use in a prospective multicenter study. Investigation of CT-free regimens may need to be focussed on selected patients only (e.g. with high HER2 expression/non-basal-like tumors). In ADAPT HR-/HER2+, early pCR after only 12 weeks of neoadjuvant P+T+pac was strongly associated with improved outcome and may thus serve as a predictive clinical marker for further treatment (de)-escalation. Clinical trial information: NCT01779206

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Abstract Details

Meeting

2021 ASCO Annual Meeting

Session Type

Oral Abstract Session

Session Title

Breast Cancer—Local/Regional/Adjuvant

Track

Breast Cancer

Sub Track

Neoadjuvant Therapy

Clinical Trial Registration Number

NCT NCT01779206

Citation

J Clin Oncol 39, 2021 (suppl 15; abstr 503)

DOI

10.1200/JCO.2021.39.15_suppl.503

Abstract #

503

Abstract Disclosures