Zheqi Li, Otto Metzger Filho, Giuseppe Viale, Patrizia dell'Orto, Leila Russo, Marie-Anne Goyette, Avni Kamat, Denise A Yardley, Vandana Gupta Abramson, Carlos L Arteaga, Laura M Spring, Kami Chiotti, Carol Halsey, Adrienne G Waks, Tari A King, Susan C Lester, Jennifer R Bellon, Eric P Winer, Paul T Spellman, Ian E Krop, Kornelia Polyak
BACKGROUND: HER2-targeting therapies have great efficacy in HER2-positive breast cancer, but resistance in part due to HER2 heterogeneity (HET) is a significant clinical challenge. We previously described that in a phase II neoadjuvant trastuzumab emtansine (T-DM1) and pertuzumab (T-DM1+P) clinical trial in early-stage HER2-positive breast cancer, none of the patients with HER2-HET tumors had pathologic complete response (pCR). METHODS: To investigate cellular and molecular differences among tumors according to HER2 heterogeneity and pCR, we performed RNA sequencing (RNA-seq) and ERBB2 FISH of 285 pre/post-treatment tumors from 129 patients in this T-DM1+P neoadjuvant trial...
February 1, 2024: Journal of Clinical Investigation