HER2-low-positive breast cancer: evolution from primary tumor to residual disease after neoadjuvant treatment

• DOI: 10.1038/s41523-022-00434-w
• Publication Date: 2022-05-20T10:04:24Z
• Authors: Federica Miglietta; Gaia Griguolo; Michele Bottosso; Tommaso Giarratano; Marcello Lo Mele; Matteo Fassan; Matilde Cacciatore; Elisa Genovesi; Debora De Bartolo; Grazia Vernaci; Ottavia Amato; Francesca Porra; PierFranco Conte; Valentina Guarneri; Maria Vittoria Dieci
• Keywords: HER2 negative

Approximately a half of breast tumors classified as HER2-negative exhibit HER2-low-positive expression. We recently described high instability expression from primary cancer (BC) to relapse. Previous studies reporting discordance in HER2 status between baseline biopsy and residual disease (RD) patients undergoing neoadjuvant treatment did not include the category. The aim this study is track evolution BC RD after treatment. Patients with available tumor tissue matched samples (in case no pCR) were included. cases sub-classified HER2-0 or (IHC 1+ 2+ ISH negative). Four-hundred forty-six Primary phenotype was: HR-positive/HER2-negative 23.5%, triple-negative (TN) 35%, HER2-positive 41.5%. 55.6% cohort significantly enriched vs. TN subgroup (68.6% 46.8%, p = 0.001 χ2 test). In all, 35.3% non-pCR (n 291) had on RD. overall rate was 26.4%, mostly driven by converting either (14.8%) (8.9%) phenotype. Among RD, 32.0% 57.1% an estimated risk relapse according proliferative burden CPS-EG score, respectively. conclusion, showed may guide personalized adjuvant for high-risk context clinical trials novel anti-HER2 antibody-drug conjugates.