Differential response to neoadjuvant chemotherapy among 7 triple-negative breast cancer molecular subtypes.

Masuda H, Baggerly KA, Wang Y, Zhang Y, Gonzalez-Angulo AM, Meric-Bernstam F, Valero V, Lehmann BD, Pietenpol JA, Hortobagyi GN, Symmans WF, Ueno NT
Clin Cancer Res. 2013 19 (19): 5533-40

PMID: 23948975 · PMCID: PMC3813597 · DOI:10.1158/1078-0432.CCR-13-0799

PURPOSE - The clinical relevancy of the 7-subtype classification of triple-negative breast cancer (TNBC) reported by Lehmann and colleagues is unknown. We investigated the clinical relevancy of TNBC heterogeneity by determining pathologic complete response (pCR) rates after neoadjuvant chemotherapy, based on TNBC subtypes.

EXPERIMENTAL DESIGN - We revalidated the Lehmann and colleagues experiments using Affymetrix CEL files from public datasets. We applied these methods to 146 patients with TNBC with gene expression microarrays obtained from June 2000 to March 2010 at our institution. Of those, 130 had received standard neoadjuvant chemotherapy and had evaluable pathologic response data. We classified the TNBC samples by subtype and then correlated subtype and pCR status using Fisher exact test and a logistic regression model. We also assessed survival and compared the subtypes with PAM50 intrinsic subtypes and residual cancer burden (RCB) index.

RESULTS - TNBC subtype and pCR status were significantly associated (P = 0.04379). The basal-like 1 (BL1) subtype had the highest pCR rate (52%); basal-like 2 (BL2) and luminal androgen receptor had the lowest (0% and 10%, respectively). TNBC subtype was an independent predictor of pCR status (P = 0.022) by a likelihood ratio test. The subtypes better predicted pCR status than did the PAM50 intrinsic subtypes (basal-like vs. non basal-like).

CONCLUSIONS - Classifying TNBC by 7 subtypes predicts high versus low pCR rate. We confirm the clinical relevancy of the 7 subtypes of TNBC. We need to prospectively validate whether the pCR rate differences translate into long-term outcome differences. The 7-subtype classification may spur innovative personalized medicine strategies for patients with TNBC.

©2013 AACR.

MeSH Terms (15)

Adult Aged Antineoplastic Combined Chemotherapy Protocols Cluster Analysis Female Gene Expression Profiling Genetic Heterogeneity Humans Middle Aged Neoplasm Grading Neoplasm Staging Recurrence Reproducibility of Results Treatment Outcome Triple Negative Breast Neoplasms

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