267P - Pathological complete response after neoadjuvant chemotherapy plus pertuzumab and trastuzumab for HER2+ early breast cancer: Real-world data from NeoPowER study

Background

The addition of pertuzumab (P) to trastuzumab (H) and standard chemotherapy (CT) as neoadjuvant treatment (NaT) for patients (pts) with HER2 positive (HER2+) breast cancer (BC), has shown to increase the pathological complete response (pCR) rate, without main safety concerns. The aim of multicentric NeoPowER trial is to evaluate safety and efficacy of P+H+CT in a real world population.

Methods

We retrospectively reviewed the electronic medical records of stage II-III, HER2+ BC pts treated with preoperative CT+H±P. The pts who received P+H+CT in 5 Emilia Romagna oncology centers (Modena, Bologna Bellaria, Bologna S.Orsola, Meldola, Rimini) between 2017-2022, were compared with a historical group who received H+CT (control) at Modena Cancer Center between 2007-2021. Clinicopathological variables were collected. Univariate and multivariate analysis were performed to assess the impact of covariates on pCR. Results were expressed as odds ratios (OR).

Results

259 pts were included in the analysis, 125 (48%) received P+H+CT. Median age was 52 years, 63% were node-positive and 62% had hormone receptors positive (HR+). Features were balanced in the two groups, 62% of pts in the P+H+CT cohort had a Ki67 ≥ 30%, vs 43% in the control. All pts received preoperative taxane-based CT: 82% and 45% of pts also received anthracyclines, in the control and P+H+CT respectively. P+H+CT pts achieved higher pCR rate than the control: 46% vs 40% (p=0.462). At univariate analysis, HR negative (OR=3.79 p<0.001), Ki67 ≥ 30% (OR=1.29 p=0.04) and the use of preoperative anthracyclines (OR=1.72 p=0.04), were statistically related to pCR. Only ER expression (OR: 0.97 p=0.004) confirmed its statistical relation to pCR at multivariate analysis.

Conclusions

NeoPowER study confirms the efficacy of neoadjuvant chemotherapy combined with dual HER2 directed therapy: a higher pCR rate is achievable in case of HR negative and ki67≥30% in pts receiving neoadjuvant P+H+CT, when compared to H+CT.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

M. Barbolini: Financial Interests, Personal, Other: Lilly, Novartis, Gentili. U.F.F. De Giorgi: Financial Interests, Personal, Advisory Board: Pfizer, BMS, MSD, PharmaMar, Astellas, Bayer, Ipsen, Novartis, EISAI, Janssen; Financial Interests, Personal, Invited Speaker: Roche, BMS, Clovis Oncology, AstraZeneca; Financial Interests, Institutional, Research Grant: AstraZeneca, Sanofi, Roche. L. Gianni: Financial Interests, Personal, Advisory Board, Advisory board in Trastuzumab Deruxtecan in her2 low breast cancer: AstraZeneca; Financial Interests, Personal, Advisory Board, Advisory board in tucatinib: Seagen; Financial Interests, Personal, Invited Speaker: Novartis, Pfizer; Non-Financial Interests, Other, Olympia Stearing Commitee: IBCSG; Other, Travel, Accommodations, Expenses: IPSEN, Novartis, Roche, Daiichi Sankyo/AstraZeneca. L. Moscetti: Financial Interests, Personal, Advisory Board: Lilly, Pfizer, Eisai; Financial Interests, Personal, Other, Honoraria: Roche; Financial Interests, Personal, Other, Honoraria: Daiichi Sankyo, Gilead, Pfizer; Financial Interests, Personal, Other, Honoraria: Novartis. C. Omarini: Financial Interests, Personal, Other: Lilly, Gentili, Novartis, Daiichi Sankyo, Seagen. F. Piacentini: Financial Interests, Personal, Other: Lilly, Gilead, Gentili, Daiichi Sankyo, Novartis. All other authors have declared no conflicts of interest.