Quantification of protein expression locally on frozen tissue sections to evaluate tumor heterogeneity

Intra-tumour heterogeneity is often linked to drug resistance and decreased survival. We here present a method to understand the topological distribution of phenotypical variants in breast cancer, by locally quantifying protein expression in frozen tissue sections. We extract regions of interest (~100 μm) using a microfluidic probe and semi-quantify protein content through antibody microarrays. Heterogeneity between the regions is analysed through Cohen D size effect and the variants are clustered according to the expression of 13 proteins across 5 patients, highlighting the presence of patients with a single phenotypical variant and others with up to three variants.