P1.16-10 Real-World Efficacy of First-Line Pembrolizumab in Patients with Advanced PD-L1 High Non-Small Cell Lung Cancer in Argentina

Abstract

Pembrolizumab monotherapy is a standard first-line (1L) treatment regimen for patients (pts) with non-small cell lung cancer (NSCLC) and a PD-L1 tumor proportion score (TPS) ≥ 50%. We aimed to study the clinical efficacy and toxicity of this approach in the real-world setting in Argentina. We conducted a retrospective, multicenter study. Patients with metastatic NSCLC and a PD-L1 TPS ≥ 50% treated in 1L with at least one dose of pembrolizumab monotherapy, from December 2016 to February 2019, were included. Data was collected from clinical records, overall response rate (ORR), progression-free survival (PFS) and overall survival (OS) were estimated. Cox regression model was performed for uni- and multivariate analysis. A total of 53 pts were included. Median age (range) was 68 years (35-88), 33 (62.3%) were male, and 46 pts (86.7%) were smokers. Most tumors were lung adenocarcinoma (N=47, 88.7%), median (IQR) PD-L1 TPS was 79% (60-87.5) and 22 tumors (41.5%) had a TPS ≥75%. EGFR/ALK/ROS1 mutations/fusions were not detected. Brain (N=10; 18.9%), liver (N=5 (9.4%) and bone (N=15; 28.3%) metastasis were present at baseline. Performance status (PS) score was 0-1 in 46 pts (86.8%) and 7 pts (13.2%) had PS 2. Six pts received baseline corticosteroid treatment. The ORR with pembrolizumab was 41.5% (95% CI: 28.1-55.8), median PD-L1 TPS (mTPS) was significantly higher in responders (mTPS 74% vs 67%, P = 0.04). Grade ≥3 immune-related adverse events occurred in 7 pts (13.2%) and 10 (18.9%) required systemic therapy with steroids. With a median-follow up of 12.9 months (95% CI: 8.4-17.6), median PFS and median OS were not reached. The estimated percentage of patients alive and without progression at 6 and 12 months was 64.8% and 55.8%. The estimated percentage of patients alive at 6 and 12 months was 77.5% and 69.4%. Median PFS and OS for patients with PS 2 was 2.4 months (95% CI: 1.7-3.1) and 4.5 months (95% CI: 3.1-6.0), respectively. After adjusting for PS, a PDL1 TPS score ≥75% was independently associated with improved PFS in multivariate analysis [HR 0.28 (95% CI: 0.09-0.92); P = 0.03) but not with OS. PS score equal to 2 was independently associated with decreased OS [HR 4.52 (95% CI: 1.06-19.28); P = 0.04] in multivariate analysis. Pembrolizumab monotherapy is tolerable and confers durable clinical benefit for patients with tumors expressing high levels of PD-L1 in the real world clinical setting. The optimal first-line immunotherapy approach for patients with PS 2 in this setting warrants further studies.