1057P Baseline circulating immature neutrophils anticipate hyperprogressive disease (HPD) upon 1st-line PD-1/PD-L1 inhibitors (ICI) in non-small cell lung cancer (NSCLC) patients (pts) and are reduced by platinum-based chemotherapy (PCT) and ICI combinations

HPD has been described in ≃14-26% of pretreated NSCLC pts upon single-agent (SA) ICI and not reported PCT-ICI. So far, no predictive biomarkers are available for early detection. treated with 1st line SA-ICI or PCT-ICI were assessed circulating neutrophils. required 3 radiological scans was defined as delta tumor growth rate (TGR) [TGR – TGR prior ICI) >50% and/or ratio (TGR ICI/ ≥2. Circulating low density neutrophils (LDNs) by flow cytometry on peripheral blood mononuclear cells (PMBCs). LDNs CD66b+CD15+ among CD11b+ PBMCs immature subtypes % CD10- LDNs. The association between outcome the role non parametric penalized model-based tests. LDNs’ sensitivity to cisplatin induced cell death tested in-vitro. 141 included: 75 66 In cohort, PD occurred 31 (41%) 6 (8%) pts. significantly higher (p=0.011) [median (Me): 43.55, interquartile range (IQR): 46.5] vs [Me: 9.44, IQR: 15.44]. associated [odds (OR): 2.88, 90% CI: 1.61; 5.16] showing a good prediction capability [cross-validated ROC AUC: 0.77, 0.51;1.00]. A 29.5% cut-off value identified Youden index discriminate from others. 10 had >29.5% being at high risk, however none them experienced it. 5 these high-risk dynamic evaluation PCT-ICI, 52.2% decrease median occurred, while SA-ICI, only 2.8% observed, suggesting that PCT prevents reducing vitro experiments also showed increased necrotic preferentially mature CD10+ Baseline is simple cost-effective predictor could select be addressed