Favourable outcome of patients with breast cancer brain metastases treated with dual HER2 blockade of trastuzumab and pertuzumab.

Dual human epidermal growth factor receptor 2 (HER2) blockade with trastuzumab and pertuzumab (TP) is a standard therapy of metastatic and localized HER2-positive breast cancer (BC), but its activity in breast cancer brain metastases (BCBM) is unknown. Patients with HER2-positive BCBM were identified from the Vienna Brain Metastasis Registry and clinical data including patient characteristics, therapies and overall survival (OS) were obtained. Patients were grouped into 'TP', 'other-HER2-targeted therapy' and 'no-HER2-targeted therapy' according to received first-line systemic therapy after diagnosis of BCBM. Radiological re-assessment of intracranial lesions was performed in patients treated with TP as systemic first-line therapy according to RANO response criteria for brain metastases (BM). A total of 252 HER2-positive BC patients with BM were available for this analysis. Patients treated with TP as systemic first-line therapy after diagnosis of BM had a significantly longer OS compared with treatment with other-HER2-targeted therapy and no-HER2-targeted therapy (44 First-line therapy with dual HER2-inhibition of TP after BM diagnosis was associated with the longest median OS times in patients with BCBM.

© The Author(s), 2021.

Conflict of interest statement: AMS has received travel support from PharmaMar. KT-S has received honoraria for lectures or advisory board participation from Roche as well as travel support from Roche, Novartis and Merck Sharp & Dohme GmbH (MSD). ZB-H has received personal fees and honoraria for participation on advisory boards from Novartis, Biomedica and Roche and travel support from Roche. FF has received travel and scientific support from Comesa, Novartis, Roche, Astra Zeneca, Pfizer, Myriad, Nanostring, Bondimed (Polytech, Integra) and Lilly, honoraria for advisory board participation from Pfizer, Astra Zeneca, Lilly and Roche, serves as editor for Springer and as founder of the Breast Analyzing Tool. GW received restricted travel grants from NX Development Corp. MP has received honoraria for lectures, consultation or advisory board participation from the following for-profit companies: Bayer, Bristol-Myers Squibb, Novartis, Gerson Lehrman Group (GLG), CMC Contrast, GlaxoSmithKline, Mundipharma, Roche, Astra Zeneca, AbbVie, Lilly, Medahead, Daiichi Sankyo, Sanofi, Merck Sharp & Dome. The following for-profit companies have supported clinical trials and contracted research conducted by MP with payments made to his institution: Böhringer-Ingelheim, Bristol-Myers Squibb, Roche, Daiichi Sankyo, Merck Sharp & Dome, Novocure, GlaxoSmithKline, AbbVie. ASB has received research support from Daiichi Sankyo (⩽10000€), Roche (>10000€) and honoraria for lectures, consultation or advisory board participation from Roche Bristol-Meyers Squibb, Merck, Daiichi Sankyo (all <5000€) as well as travel support from Roche, Amgen and AbbVie. RB has received research support from Daiichi, Novartis, Roche and honoraria for lectures from Accord, Astra-Zeneca, BMS, Celgene, Eli-Lilly, Novartis, Pfizer, Pierre-Fabre, Roche, Sandoz as well as for advisory board participation from Astra-Zeneca, Celgene, Daichi, Eisai, Eli-Lilly, MSD, Novartis, Pfizer, Pierre-Fabre, Puma, Roche, Samsung. The other authors declare that they have no competing interests.