Targeted sequencing of plasma cell-free DNA to predict response to PD1 inhibitors in advanced non-small cell lung cancer.

OBJECTIVES: Tumor mutational burden is an emerging biomarker of response to immune checkpoint inhibitors (ICI), whose clinical adoption is challenging. We hypothesized that targeting limited but relevant genetic alterations in plasma cell-free DNA along with early monitoring may non-invasively predict response to ICI in advanced non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: Plasma samples from patients with progressive NSCLC collected before ICI initiation and at 1 month were profiled from responders (R: PFS > 6 months) and non-responders (NR: progressive disease at first evaluation) using amplicon sequencing of hotspots and coding regions from 36 genes. The molecular profile of ctDNA, and its early kinetics were analyzed. RESULTS: 97 patients were analyzed, of which 86 (39 R, 47 NR) were evaluable. Alterations in ctDNA were detectable in 67/86 baseline samples (78%). The detection of a targetable oncogenic driver was associated with a 2 months PFS. The presence of a PTEN or STK11 mutation was correlated with early progression (HR 8.9, p = 0.09 for PTEN, HR 4.7, p = 0.003 for STK11), while transversion mutations (Tv) in KRAS and TP53 predicted better outcomes (HR 0.36, p = 0.011 for TP53 Tv; HR 0.46, p = 0.11 for KRAS Tv). Patients with a low "immune score" (driver and/or PTEN or STK11 mutation and/or without KRAS or TP53 Tv) derived poor outcomes (median PFS 2 months), compared with patients with a high immune score (no driver, no PTEN or STK11 and with KRAS or TP53 Tv (median PFS 14 months, p = 0.0001, HR 2.96). Early changes in the ctDNA allele fraction (AF) of 65 specimens were correlated with clinical outcomes (14 months PFS if AF decreases vs. 2 months if AF increases, p < 0.0001). CONCLUSION: Targeted sequencing of plasma ctDNA and monitoring its early variations can predict response to ICI.

Survival of patients with non-small cell lung cancer having leptomeningeal metastases treated with immune checkpoint inhibitors.

INTRODUCTION: Patients with non-small cell lung cancer (NSCLC) experience leptomeningeal metastases (LM) in 3-9% of cases. Because overall survival (OS) and performance status are very poor, they are mostly excluded from clinical trials. Here, we evaluated survival of patients with NSCLC having LM treated with immune checkpoint inhibitors (ICIs). METHODS: A prospectively collected list of patients with advanced NSCLC treated with ICIs between November 2012 and July 2018 in 7 European centres was merged. All patients with LM before ICI start were selected, data were retrospectively added and patients were classified according to the National Comprehensive Cancer Network (NCCN) LM prognostic classification (good/poor). Progression-free survival (PFS) and OS on ICIs were evaluated. RESULTS: Nineteen of 1288 (1.5%) patients had LM; 73.7% had synchronous brain metastases; 73.7% had neurological symptoms at the start of ICIs and 52.6% were in the NCCN LM good prognosis group. Programmed death ligand-1 (PD-L1) expression was known for 42.1% of patients (87.5% positive). Median follow-up was 13 months from the start of ICIs, and median (95% confidence interval [CI]) PFS on ICIs was 2.0 (1.8-2.2) months. Six-month PFS rate was 21.0% and was significantly higher in the NCCN good versus poor prognostic group: 40% vs 0% (p = 0.05). Twelve-month PFS rate was 0%. Median (95% CI) OS from the start of ICIs was 3.7 (0.9-6.6) months. Six-month OS rate was 36.8%, and 12-month OS rate was 21.1%; both were not statistically significantly different for the good versus poor NCCN prognostic group (p = 0.40 and p = 0.56, respectively). CONCLUSION: Some patients with NSCLC having LM do benefit from ICI treatment; specifically, those in the NCCN LM good prognosis group can obtain a long survival.

PD-L1 expression in circulating tumor cells of advanced non-small cell lung cancer patients treated with nivolumab.

BACKGROUND: Inhibitors of the PD-1/PD-L1 immune checkpoint have become a standard of care in non-small cell lung cancer (NSCLC). Patient selection, currently based on PD-L1 expression on tumor tissue, is limited by its temporal and spatial heterogeneity. We hypothesized that liquid biopsy with PD-L1 analysis on circulating tumor cells (CTCs) might overcome this limitation. METHODS: Blood samples were prospectively collected from patients with advanced NSCLC before nivolumab treatment and at the time of progression. CTCs were isolated using a cell size-based technology. PD-L1 expression was assessed by immunofluorescence on CTCs and immunohistochemistry on tissue biopsies. RESULTS: 113 specimens from 96 patients were collected. Baseline PD-L1 expression could be assessed on 72% and 93% of tissue and CTC, respectively. CTCs were more frequently found to be PD-L1 positive than tissue (83% vs. 41%) and no correlation was observed between tissue and CTC PD-L1 expression (r = 0.04, p = 0.77). Pre-treatment high CTC number was associated with increased risk of death and progression (HR1.06, p = 0.03 for OS; HR1.05, p = 0.02 for PFS). The presence of pre-treatment PD-L1+CTC was not significantly correlated with outcomes but a higher baseline PD-L1+ CTC number (≥1%) was observed in the "non-responders" group (PFS <6 months) (p = 0.04) and PD-L1+CTC were seen in all patients at progression. CONCLUSION: Assessment of PD-L1 expression in CTCs is feasible and CTCs are more often positive than in tissue. Pre-treatment PD-L1+CTCs are associated with bad prognosis in patients treated with PD-1 inhibitors.