Disclosure GB has received consulting fee from Roche, AstraZeneca, Novartis, MSD, Sanofi, Daiichi Sankyo, and Exact Science; honoraria for speakers’ bureaus from Roche, Pfizer, AstraZeneca, Lilly, Novartis, Neopharm Israel, MSD, Chugai, Daiichi Sankyo, EISAI, and Exact Science; support for attending meetings from Roche, Pfizer, and AstraZeneca; is co-inventor of ‘European patent Application N. 12195182.6 and 12196177.5 titled PDL-1 expression in anti-HER2 therapy’—Roche—Issued (no compensation provided); and has served on the advisory boards for Roche, Pfizer, Daiichi Sankyo, Lilly, MSD, Novartis, AstraZeneca, Genomic Health, EISAI, Gilead, and Seagen. LL has received consulting fee from Exact Science; honoraria for speakers’ bureaus from Gilead, Exact Science, and EISAI; support for attending meetings from Lilly and Gilead; and has served on the advisory boards for Lilly, Exact Science, AstraZeneca, and Daiichi Sankyo. GV has served on the advisory boards for Gilead. LG has received consulting fees from Novartis and Odonate Therapeutics; honoraria for lecture from Roche; support for attending meetings from Pfizer; is co-inventor of ‘European patent Application N. 12195182.6 and 12196177.5 titled PDL-1 expression in anti-HER2 therapy’—Roche—Issued (no compensation provided); has served on the advisory boards for AstraZeneca, Celgene, Genentech, Merk Sharp & Dohme, Roche, Pfizer, and Sanofi Aventis; and is Chair of the Breast Cancer Research Committee of Fondazione Michelangelo.