A nanofluidic immunoassay system to develop proteomic responsive biomarkers in non-small cell lung cancer.

Abstract

27 Background: Molecular targeted therapy is widely used to treat non-small cell lung cancer (NSCLC). However, errors in predicting response to targeted therapies are 20-30%, based on sequencing or FISH, and patient specimen are at times not sufficient for conventional protein technologies. Developing clinically feasible proteomic biomarkers may be valuable to identify patients who may benefit from targeted therapy. Methods: NanoPro technology (ProteinSimple), is a capillary-based isoelectric-focusing (IEF) immunoassay system, which detects and quantifies multiple protein phosphorylation isoforms that are not readily assessed by traditional immunoassays. The platform only uses nanograms of protein for analysis. Results: We studied dynamic phosphoprotein activities in NSCLC cells (PC9, H827, H4006, H2122 and H322) treated with EGFR or/and MEK inhibitors. In MEK inhibitor (PD325901) treated cells, NanoPro showed that the drug efficiently inhibited Erk phosphorylation, and also revealed a complex MEK response profile which was not detectable by Western blotting, demonstrating its on-target effect. NanoPro also identified a MEK2 signature that associated with erlotinib sensitivity and distinguished erlotinib sensitive from resistant cells. This MEK2 signature was further confirmed in acquired resistant cells to erlotinib (H827R, H4006R). In a H827 xenograft study, NanoPro was able to detect and distinguish human Erk1 isoform from mouse Erk1 based on their pI difference, and clearly demonstrated that erlotinib effectively inhibited Erk phosphorylation in human xenograft cancer cells but not in surrounding mouse stromal cells. We further demonstrated that Nanopro could monitor erlotinib and AZD2644 response in a KrasG12C NSCLC patient (NCT01229150) by profiling 18 signaling molecules with as little as 4ug tumor material. Conclusions: NanoPro provides a valuable platform to monitor signaling response to targeted therapy. Nanopro assesses protein phosphorylation both qualitatively and quantitatively using small sample size, thus creates new opportunities for pharmacodynamic biomarker assessment in clinical studies.