Abstract P6-12-08: Serum biomarkers identification using quantitative proteomics in patients with HER2-positive inflammatory breast cancer receiving trastuzumab plus bevacizumab-based chemotherapy (BEVERLY 2 trial)

Abstract

Background Inflammatory breast cancer (IBC) is a rare but aggressive form of locally advanced breast cancer, the optimal systemic treatment of which is still discussed. Beverly 2 trial was a phase II study evaluating the efficacy and safety of a preoperative regimen associating bevacizumab, trastuzumab, and chemotherapy in 52 patients with non-metastatic HER2-positive IBC, reporting a promising rate of pathological complete response (pCR, 63.5%, 95% CI 49.4–77.5; Pierga et al, Lancet Oncol, 2012). During the study, serum samples were collected at baseline and subjected to proteomic-based approaches to identify circulating biomarkers predictive of treatment response. Methods Baseline serum samples from responsive (pCR, according to Sataloff classification, n = 12) and non-responsive (no pCR, n = 11) patients were subjected to isobaric Tag for Relative and Absolute Quantification (iTRAQ)-based proteomics. Samples were pooled according to pCR and hormone receptor (HR) status, to constitute 4 independent mixes (pCR/HR-positive, pCR/HR-negative, nopCR/HR-positive, nopCR/HR-negative). Each of them underwent immuno-depletion of highly abundant proteins, concentration, reduction, alkylation and tryptic digestion. Then, each mix was fractionated and subjected to iTRAQ identification and quantitation using nano-liquid chromatography (LC) and electrospray ionisation (ESI)-orbitrap tandem mass spectrometry (MS/MS) (LTQ-orbitrap, Thermofisher). Differentially expressed proteins were analysed using IPA (IngenuitySystems) to highlight biological functions and signalling pathways that were most significantly enriched. Results iTRAQ-based measurements identified and quantified a total of 302 serum proteins. Among them, 48 proteins displayed a significant (fold-change > 1.5 and p-value < 0.05) differential expression between pCR and noPCR pts (18 proteins down-regultated and 30 proteins up-regulated in pCR patients), some of them previously described to be involved in breast cancer biology and/or angiogenesis, including : Alpha-1-acid glycoprotein 1, von Willebrand factor, Galectin-3-binding protein, serum amyloid A-1, Apolipoprotein E, Pigment epithelium-derived factor, Corticosteroid-binding globulin (down-regulated proteins in pCR patients); serum amyloid P-component, angiotensinogen, plasma serine protease inhibitor, carbonic anhydrase 1, mannose-binding protein C, hyaluronan-binding protein 2, peroxiredoxin-2, properdin, ADAMTS13, tetranectin, biotinidase, lumican (up-regulated proteins in pCR patients). Proteins with differential expression during treatment were involved in various biological processes, including cell-to-cell signaling and interaction, lipid metabolism, small molecule biochemistry, molecular transport, cellular function and maintenance as well as various canonical pathways such as acute phase response signalling, LXR/RXR activation and coagulation system. Conclusion iTRAQ-based quantitative proteomics identify serum proteins that could predict the therapeutic response to pre-operative trastuzumab plus bevacizumab-based chemotherapy in HER2-positive IBC. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-12-08.