Recently, a HER2-targeting antibody-drug conjugates (HER2-ADC) was approved to treat HER2-low breast cancer (BC), currently defined by the immunohistochemical (IHC) HER2-expression ASCO/CAP scores of 1+ or 2+ without
We retrospectively analyzed 22 untreated BC samples with single cell RNA-sequencing and centralized HER2 IHC data. IHC staining for HER2 (Agilent, GA0485, RTU) was performed and scored according to ASCO/CAP 2018 guidelines. Single cell data were retrieved from the original publication (PMID: 33958794) and only the cancer cells (n= 31016) were retained.
We identified 1 HER2-zero (with no staining on tumor cells), 16 HER2-low (4 HER2-1+, 12 HER2-2+ FISH-negative) and 5 HER2-positive samples. The median percentage of cells expressing
Single cell data might provide more granularity into the tumor-specific expression levels of HER2. Future research is needed to investigate whether single-cell
The authors.
Has not received any funding.
H. Wildiers: Financial Interests, Institutional, Advisory Board: Roche, Lilly, AstraZeneca, Daiichi Sankyo, PSI Cro AG, KCE, MSD, MSD, E Squared Communications LLC; Financial Interests, Institutional, Invited Speaker: Eisai, AstraZeneca; Financial Interests, Institutional, Other, Consultancy fee: AbbVie, Immutep Pty; Financial Interests, Institutional, Expert Testimony: Daiichi Sankyo; Financial Interests, Institutional, Other, Consultancy: Daiichi Sankyo; Financial Interests, Institutional, Research Grant, Grant to the Leuven Breast Center to support the research database: Roche; Financial Interests, Institutional, Research Grant, Grant to institute to perform a multicentric national academic trial: Novartis; Other, Travel & accomodations: Pfizer; Other, Travel & accomodation: Roche; Other, Subscription fee: Gilead. K. Punie: Financial Interests, Institutional, Advisory Board: AstraZeneca, Novartis, Roche, Vifor Pharma, Eli Lilly, Pierre Fabre, McCann Health, Roularta, Teva, Gilead Sciences, Pfizer, Gilead, MSD; Financial Interests, Institutional, Invited Speaker: Pfizer, Roche, Novartis, Eli Lilly, Mundi Pharma, MSD, Medscape, MSD; Financial Interests, Institutional, Other, Consultancy: Roche; Financial Interests, Personal, Other, Consultancy: Gilead, Novartis, MSD, Roche; Financial Interests, Personal, Invited Speaker: Sanofi, AstraZeneca; Financial Interests, Personal, Advisory Board: Seagen; Financial Interests, Institutional, Funding: Sanofi; Non-Financial Interests, Principal Investigator: EORTC 1745-ETF-BCG trial; Non-Financial Interests, Other, Committee member: ESMO Young Oncologists Committee; Non-Financial Interests, Invited Speaker: BSMO; Non-Financial Interests, Other, Committee Member: ESMO Resilience Task Force; Non-Financial Interests, Advisory Role: Commission personalized medecine Federal Government Belgium; Non-Financial Interests, Advisory Role, External Scientific Advisor: European Medicine Agency. G. Floris: Financial Interests, Institutional, Advisory Board, paid to institution: AstraZeneca. All other authors have declared no conflicts of interest.