We first used the GeoMx Digital Spatial Profiling (DSP) system in a discovery cohort of 56 NSCLC patients treated with PD-1 axis inhibitors at Yale (USA)...we assessed pre-treatment whole tissue sections from a cohort of 128 NSCLC patients treated with single-agent PD-1 axis inhibitor....Using continuous log-scaled data, we found 5 markers independently associated with progression-free survival (PFS) in the tumor compartment (including PD-L1, p = 0.002). Among the novel candidate predictors, tumor cell CD44, a marker of pluripotency and stemness, was associated with longer PFS (multivariate HR = 0.63, p= 0.002)....we orthogonally validated that CD44 expression in the tumor compartment was associated with longer PFS (p <0.001) and overall survival (OS) (p = 0.03). In the external validation cohort, CD44 expressed in the tumor compartment, but not in the immune compartment, was predictive of clinical benefit (OR 1.22, p = 0.018), and was significantly associated with longer PFS (first tertile cutpoint: HR 0.62, p = 0.03).

We initially assessed a discovery cohort of 56 patients with NSCLC treated with PD-1 axis inhibitors at Yale Cancer Center….we identified CD44 expression in the tumor compartment (pan-cytokeratin (CK)+) as a novel predictor of prolonged progression-free survival (PFS) (multivariate HR=0.68, p=0.043) in the discovery set.