EarlyR genomic signature to predict pathological complete response following neoadjuvant anthracycline-taxane chemotherapy in estrogen-receptor positive (ER+) breast cancer.

Abstract

579 Background: EarlyR is a prognostic signature computed from expression values of ESPL1, SPAG5, MKI67, PLK1 and PGR that stratifies ER+ breast cancer (BC) into EarlyRLow, EarlyRInt, and EarlyRHigh risk strata. Here, we show that EarlyR is also predictive of pathological complete response (pCR) following neoadjuvant anthracycline-taxane (AT) based chemotherapy. Methods: The ability of EarlyR gene signature to predict pCR was assessed in Affymetrix microarrays datasets (GSE25065, GSE25066, GSE20194, GSE20271; n = 541, pCR = 42 (7.8%) collectively labeled as Cohort A) derived from patients with ER+ breast cancer treated with neoadjuvant TFAC or FEC. For 2 of these datasets (GSE25065, GSE25066 (n = 291)) distant metastasis-free survival (DMFS) results were also available. The DMFS data in cohort A were compared to that of BC patients not treated with chemotherapy (denoted Cohort B, n = 1269) derived from ER+ samples from 7 GEO datasets (GSE3494, GSE7390, GSE12093, GSE6532, GSE2034, GSE11121, GSE17705). Results: In cohort A, EarlyR is a significant predictor of pCR (p = 1.0 x 10-6) (EarlyRLow, n = 273, pCR = 5, 1.8%; EarlyRInt, n = 11, pCR = 1, 9.1% and EarlyRHigh, n = 256, pCR = 36, 14.1%). Notably, 86% of the 42 cases with pCR have EarlyRHigh. Of the 291 patients with 8-year DMFS data from Cohort A, who had received chemotherapy, the survival of EarlyRHigh [0.79 (95%CI 0.70-0.89)] was nearly the same as that of EarlyRLow [0.82 (95%CI 0.74-0.90)]. In contrast, in cohort B, who were not treated with chemotherapy, 8-year DMFS is significantly (p = 5 x 10-15) lower in EarlyRHigh [0.57 (95%CI 0.51-0.64)] than in EarlyRLow[0.81 (95%CI 0.78-0.84)]. Conclusions: EarlyR is a strong predictor of pathological complete response in patients treated with TFAC or FEC. In addition, EarlyR also predicts poor DMFS outcomes for patients in EarlyRHigh not receiving chemotherapy. More importantly, neoadjuvant chemotherapy dramatically improved survival of patients in EarlyRHigh. These results document that EarlyR identifies a set of patients, EarlyRHigh, with a high risk of distant metastasis, who are also likely to respond favorably to chemotherapy.