The erbB2+cluster of the intrinsic gene set predicts tumor response of breast cancer patients receiving neoadjuvant chemotherapy with docetaxel, doxorubicin and cyclophosphamide within the GEPARTRIO trial

Gene expression profiting using Affymetrix HG-U133 Arrays (22,500 genes) was performed on fresh frozen pretherapeutic core biopsies from 50 patients undergoing neoadjuvant chemotherapy (NAC) with docetaxel, adriamycin, cyclophosphamide (TAC) within the GEPARTRIO trial. The Sortie classification based on the intrinsic gene set revealed four different subgroups in our cohort (normal-like: 14%, basal-like: 20%, erbB2+: 22% and luminal: 44%), which is in tine with the original description. High genomic grade but not histopathological grading was statistically different within the four subgroups (P < 0.001). About 45.5% of tumors classified according to erbB2+ cluster showed a pathological complete response compared to 0% in the normal-like, 10.0% in the basal-like and 9.1% in the luminal. subgroup (P = 0.024). There was a trend to less tumor relapses in the erbB2+ subgroup (0%) compared to the normal-like (28.6%), basal-like (30.0%) and luminal (13.6%) cluster (P = 0.215). Our data suggest that the molecular tumor subtypes based on the intrinsic gene set can be used to predict tumor response according to NAC. (c) 2007 Elsevier Ltd. All rights reserved.