Evaluation Of Blood-Based Proteomic Biomarkers Associated With Response To Anti-Pd-1 Treatment In Nsclc.

e21531 Background: Immune checkpoint inhibitors have remarkably improved the natural history of patients with non-small cell lung cancer (NSCLC), with improved clinical responses and overall survival compared to standard therapy. However, most unselected NSCLC patients do not respond, highlighting the need of theranostic biomarker discovery. In a cohort of NCSLC patients treated with anti-PD-1-blockade, we investigate baseline blood-based parameters with a high-throughput quantitative proteomics workflow, based on data independent acquisition mass spectrometry (DIA-MS). Quantified proteins are evaluated as potential circulating biomarkers for predicting the response to therapy. Methods: Plasma samples from 49 NSCLC subjects treated with anti-PD-1-blockade were prepared for mass spectrometry. All samples were analyzed on a Thermo Scientific Q Exactive HF-X operated in a DIA mode using capillary flow liquid chromatography with separation over a 40 min gradient. DIA data was extracted with Spectronaut to quantify expressed proteins. Results: Across all samples, 605 proteins were quantified and 17 were significantly associated (log2 fold change > 0.58 and q-value < 0.05) with Responders (SD + PR) vs Non-Responder (PD) groups. Functional mapping and unsupervised clustering of regulated proteins identifies three major subject groups based on protein expression profiles: Group A is characterized by high expression of acute phase proteins (e.g. SAA1/2, CRP), Group B has low overall protein expression, and Group C has high expression glycolysis related enzymes (ALDOA, GAPDH) and focal adhesion proteins (VCL). Consistent with previous studies the Group A, with high levels of acute phase proteins, had poor overall survival relative to the other two families (HR = 2.2 [1.2-4.2], p = 0.003). Notably, Group C is comprised largely of Non-Responders (8/12) yet had improved overall survival relative to Group A (HR = 2.5 [1.2-5.0], p = 0.004). Conclusions: Plasma proteomic profiling with capillary flow DIA-MS enables quantification protein profiles in a hypothesis free manner. Poor outcomes on anti-PD-1 therapy was confirmed for subjects with elevated acute phase proteins. However, a subgroup with high focal adhesion and glycolysis proteins had improved survival despite containing non-responder subjects, requiring further investigation.