Molecular subtyping to predict better clinical and pathologic tumor response in operable early-stage breast cancer treated with docetaxel-capecitabine with or without trastuzumab.

Abstract

11090 Background: Classification into molecular subtypes is important for the selection of therapy for patients with early breast cancer. Here we determine rates of pathological complete response (pCR) in early stage breast cancer to neoadjuvant capecitabine plus docetaxel, +/- trastuzumab, and investigate MammaPrint together with the molecular subtyping profile BluePrint as markers of pathological response in comparison to other biomarkers. Methods: This analysis was carried out on data from 122 patients enrolled in a multicenter study (XeNA) of neoadjuvant therapy for four 21-day cycles with capecitabine 825 mg/m2 plus docetaxel 75 mg/m2if HER2-, and a standard trastuzumab dose if HER2+ (Glück , BCRT 2011). Clinical and pathological features, TP53 mutation analysis and PAM50 results were collected through GEO at NCBI (GSE22358). MammaPrint and BluePrint outcomes were determined from the available gene expression data and resulted in 4 distinct molecular groups: Luminal A (MammaPrint Low Risk/Luminal-type), Luminal B (MammaPrint High Risk/ Luminal-type), Basal-type and HER2-type. Results: In patients who completed 4 cycles of chemotherapy and surgery the overall pCR rate was 16%. Stratified by BluePrint pCR was observed in 1/15 (7%) of the Luminal A and 2/44 (5%) of Luminal B, in 10/22 (45%) of the HER2-type and in 7/41 (17%) of the Basal-type. The response rate among TP53 mutated patients was 6/61 (26%), which was significantly higher than TP53 wild-type patients (3/54 4%; p=0.012). Concordance of BluePrint/MammaPrint with PAM50 molecular subtyping was 61%. Conclusions: Molecular Subtyping with BluePrint and MammaPrint can identify better outcomes of patients in the neo-adjuvant setting. Patients with Luminal A breast cancer have a good baseline prognosis with excellent survival and may not benefit from chemotherapy (Glück, SABCS 2013). MammaPrint and BluePrint provide predictive information for patients treated with treated with docetaxel-capecitabine +/- trastuzumab.