Abstract 8P
Background
The predictive accuracy of the HER2DX pCR score for pCR following anti-HER2-based neoadjuvant CT, as compared to MRI response, is unknown. With the increasing reliance on MRI response in clinical trials for guiding surgical and systemic therapy decisions, understanding the discrimination ability of HER2DX pCR score is crucial. This study assesses the effectiveness of HER2DX pCR score in predicting pCR beyond MRI response.
Methods
HER2DX was assessed on pre-treatment baseline FFPE tumor biopsies from 147 patients (pts) with stage I-III BC treated with trastuzumab-based CT at Hospital Clinic Barcelona. The primary aim was the association of HER2DX pCR score as a continuous and as a group variable with pCR status, factoring in MRI binary response (>90% response vs. others). The secondary aim was the predictive capacity of HER2DX pCR score within MRI-responders and non-responders. Logistic regression models were used for statistical analysis.
Results
MRI data pre- and post-therapy were available for 131 (89.7%) pts. The overall pCR rate in this subset was 51.9% (95% CI 43.0-60.7%). In univariable analysis, MRI response was associated with pCR (63.o% vs 34.0%, odds ratio [OR]=3.30, p<0.001), as well as HER2DX pCR continuous score (OR=1.57, p<0.001) and HER2DX pCR groups (high vs low: OR=16.51, p<0.001). Area under the curve was 0.64 for MRI and 0.78 for HER2DX pCR-groups. In a multivariable model, HER2DX pCR showed a significant association with pCR (high vs low: OR=13.87, p<0.001), while MRI response did not (OR=2.06, p=0.100). HER2DX pCR-score also was associated with pCR in both MRI-response and MRI-non-response groups (all p<0.001). Among MRI-responders, pCR rates were 72.4%, 74.2%, and 33.3% in the high, medium, and low HER2DX pCR score categories, respectively. Among MRI-non-responders, the pCR rates were 80.9%, 61.5%, and 3.6%, respectively.
Conclusions
The HER2DX pCR score outperforms MRI response as a predictor of pCR in HER2+ BC undergoing anti-HER2-based neoadjuvant chemotherapy. It reliably predicts pCR rates regardless of MRI response status, emphasizing its effectiveness in guiding neoadjuvant treatment optimization.
Legal entity responsible for the study
Department of Medical Oncology, Hospital Clinic of Barcelona, Barcelona.
Funding
Has not received any funding.
Disclosure
T. Pascual: Financial Interests, Personal, Invited Speaker: Pfizer/ AstraZeneca / Veracyte / Novartis; Financial Interests, Personal, Advisory Board: Roche/Genentech, Novartis. O. Martínez-Sáez: Financial Interests, Personal, Invited Speaker: Novartis, Eisai; Financial Interests, Personal, Advisory Board: Roche; Financial Interests, Personal, Other, Travel expenses: Roche; Financial Interests, Personal, Other, Medical advisory: Reveal Genomics. L. Pare Brunet: Financial Interests, Institutional, Full or part-time Employment: Reveal Genomics S.L.; Financial Interests, Institutional, Other, Patent pending: In vitro method for the prognosis of patients suffering from HER2-positive breast cancer - 905333: SOLTI; Financial Interests, Institutional, Other, Patent filed: EP23382703: Reveal Genomics S.L.; Financial Interests, Institutional, Other, Patent filed: EP23383369: Reveal Genomics S.L. G. Villacampa Javierre: Financial Interests, Personal, Invited Speaker, Invited speaker in a course: MSD; Financial Interests, Personal, Advisory Board: AstraZeneca; Financial Interests, Personal, Invited Speaker, Invited speaker in an internal training: Pierre Fabre, GSK; Financial Interests, Personal, Invited Speaker, Internal discussion about the interpretation of some published results: Pfizer; Financial Interests, Personal, Other, Collaborations with specific projects: Reveal Genomics. A. Vivancos: Financial Interests, Personal, Advisory Board: Roche, Bristol Myers Squibb, Guardant Health, Bayer, INCYTE; Financial Interests, Personal, Stocks/Shares: Reveal Genomics; Financial Interests, Institutional, Research Grant, Preclinical Research Grant: Bristol Myers Squibb, Roche, Incyte. M.J. Vidal Losada: Financial Interests, Personal, Advisory Board: Novartis/Pfizer, Roche, Pfizer, AstraZeneca/Daiichi Sankyo; Financial Interests, Personal, Invited Speaker: Novartis/Pfizer, Roche/Genentech, AstraZeneca/Daiichi Sankyo, Gilead Sciences, Veracyte, Guardanthealth; Financial Interests, Personal, Other, Travel, Accommodations, expenses: Pfizer; Financial Interests, Personal, Other, Travel, Accommodations, Expenses: Gilead Sciences. F. Schettini: Financial Interests, Personal, Invited Speaker: Novartis, Gilead, Daiichi-Sankyo; Financial Interests, Personal, Advisory Board: Pfizer; Financial Interests, Personal, Other, Travel expenses: Novartis, Gilead, Daiichi-Sankyo. E. Segui Solis: Financial Interests, Personal, Invited Speaker: Novartis, Veracyte, Pfizer, Daiichi Sankyo, Eisai; Financial Interests, Personal, Advisory Board: Pfizer, Seagen; Financial Interests, Personal, Full or part-time Employment: SOLTI; Financial Interests, Personal, Research Grant: Amgen. P. Villagrasa Gonzalez: Financial Interests, Personal, Full or part-time Employment, CEO and co-founder of the company: Reveal Genomics S.L.; Financial Interests, Personal, Ownership Interest: Reveal Genomics S.L.; Financial Interests, Personal, Royalties, PCT/EP2021/086493 - in vitro method for the prognosis of patients suffering from HER2-positive breast cancer: Reveal Genomics S.L. A. Prat: Financial Interests, Personal, Invited Speaker: Roche, 1TRIALSP, S.L.; Financial Interests, Personal, Invited Speaker, Lecture fees: Novartis, Daiichi Sankyo; Financial Interests, Personal, Advisory Board, Advisory role/consultancy: Novartis, Pfizer, Peptomyc; Financial Interests, Institutional, Invited Speaker, Clinical trials: Daiichi Sankyo; Financial Interests, Institutional, Other, Contracted research: Boehringer, Medica Scientia inno. Research; Financial Interests, Personal, Advisory Board: AstraZeneca, Reveal Genomics; Financial Interests, Personal, Member of Board of Directors, Leadership role: Reveal Genomics, SL.; Financial Interests, Personal, Stocks/Shares: Reveal Genomics; Financial Interests, Personal, Royalties: Reveal Genomics, International Oncology Bureau, S.L.,; Financial Interests, Institutional, Invited Speaker: Roche, AstraZeneca, Novartis; Financial Interests, Personal and Institutional, Invited Speaker: Daiichi Sankyo; Financial Interests, Institutional, Funding: Reveal Genomics; Non-Financial Interests, Institutional, Other, Leadership roles: Patronage committee: Actitud Frente al Cáncer Foundation; Non-Financial Interests, Personal, Other, Asociación Española de Investigación sobre el Cáncer: ASEICA; Non-Financial Interests, Personal, Other, Research Foundation that gives grants to researchers: FERO. F. Brasó-Maristany: Financial Interests, Personal, Full or part-time Employment, part time employment: Reveal Genomics SL; Financial Interests, Personal, Other, Patents filed: EP23382703 and EP23383369: Reveal Genomics SL; Financial Interests, Personal, Other, Patents filed: PCT/EP2022/086493, PCT/EP2023/060810: Fundació de Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer. All other authors have declared no conflicts of interest.