Changes in Triple-Negative Breast Cancer Molecular Subtypes in Patients Without Pathologic Complete Response After Neoadjuvant Systemic Chemotherapy.

PURPOSE: Lehmann et al have identified four molecular subtypes of triple-negative breast cancer (TNBC)-basal-like (BL) 1, BL2, mesenchymal (M), and luminal androgen receptor-and an immunomodulatory (IM) gene expression signature modifier. Our group previously showed that the response of TNBC to neoadjuvant systemic chemotherapy (NST) differs by molecular subtype, but whether NST affects the subtype was unknown. Here, we tested the hypothesis that in patients without pathologic complete response, TNBC subtypes can change after NST. Moreover, in cases with the changed subtype, we determined whether epithelial-to-mesenchymal transition (EMT) had occurred. MATERIALS AND METHODS: From the Pan-Pacific TNBC Consortium data set containing TNBC patient samples from four countries, we examined 64 formalin-fixed, paraffin-embedded pairs of matched pre- and post-NST tumor samples. The TNBC subtype was determined using the TNBCtype-IM assay. We analyzed a partial EMT gene expression scoring metric using mRNA data. RESULTS: Of the 64 matched pairs, 36 (56%) showed a change in the TNBC subtype after NST. The most frequent change was from BL1 to M subtypes (38%). No tumors changed from M to BL1. The IM signature was positive in 14 (22%) patients before NST and eight (12.5%) patients after NST. The EMT score increased after NST in 28 (78%) of the 36 patients with the changed subtype (v 39% of the 28 patients without change; P = .002254). CONCLUSION: We report, to our knowledge, for the first time that the TNBC molecular subtype and IM signature frequently change after NST. Our results also suggest that EMT is promoted by NST. Our findings may lead to innovative adjuvant therapy strategies in TNBC cases with residual tumor after NST.

BRCA mutations in women with inflammatory breast cancer.

BACKGROUND: Inflammatory breast cancer (IBC) often affects women at a relatively young age. To the authors' knowledge, the rate of BRCA variants among patients with IBC is not known. To determine the association between BRCA status and IBC, the authors evaluated its rate and compared the clinicopathologic characteristics of patients with IBC with those of patients with other breast cancers (non-IBC). METHODS: Patients who presented at the study institution's cancer genetics program and who underwent BRCA genetic testing were included in the current study. The authors compared clinicopathologic data between patients with IBC and those with non-IBC using propensity score matching to identify predictors. RESULTS: A total of 1789 patients who underwent BRCA genetic testing (1684 with non-IBC and 105 with IBC) were included. BRCA pathogenic variants were found in 27.3% of patients with non-IBC and 18.1% of patients with IBC (P = .0384). After propensity score matching, there were no significant differences noted between patients with IBC and those with non-IBC, including the rate of BRCA pathogenic variants (P = .5485). However, a subgroup analysis of the 479 patients with BRCA pathogenic variants demonstrated that patients with IBC (19 patients) were diagnosed at significantly younger ages compared with patients with non-IBC (P = .0244). CONCLUSIONS: There was no clear association observed between BRCA pathogenic variants and IBC. However, among patients who tested positive for BRCA pathogenic variants, those with IBC were younger at the time of diagnosis compared with those with non-IBC breast cancers. These results confirm that genetic testing is important for patients with IBC who meet the current clinical criteria for genetic testing in breast cancer. Cancer 2018;124:466-74. © 2017 American Cancer Society.