Response to first-line therapies in metastatic lung adenocarcinoma with low PD-L1 expression: A multi-center retrospective study.

Abstract

e20574 Background: For metastatic lung adenocarcinoma with low PD-L1 expression (tumor proportion score:1-49%), chemotherapy in combination with immune checkpoint inhibitors (IC), with bevacizumab (BC), or with both (IBC) have been established as standard first-line options. However, the optimal scheme is still undetermined. Methods: This retrospective study enrolled 125 metastatic lung adenocarcinoma patients with low PD-L1 expression from four cancer centers. All the patients received IC, BC, or IBC as the first-line therapies. Propensity score matching (PSM) with a ratio of 1:1:1 was used to balance the inter-group clinical characteristics. Efficacy, including objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS), as well as safety were evaluated. Results: 35 of the 125 patients received IBC, 37 received BC, and 53 received IC. After PSM, a total of 35 pairs of patients were enrolled in the analysis. Patients receiving IBC (ORR: 57.1%, DCR:100%) or IC (ORR: 57.1%, DCR: 91.4%) obtained superior ORR and DCR in relative to those receiving BC (ORR: 45.7%, DCR: 82.9%). However, only IBC (median PFS: 20.47m; median OS: not research) rather than IC (median PFS: 10.0m; median OS: 21.36m) treatment generated significantly prolonged PFS and OS compared with BC (median PFS: 9.43m, P = 0.007; median OS: 23.2m, P = 0.048). We further analyzed the survival benefit based on different clinical and molecular features. We found patients with female gender had more significant OS benefit from IBC treatment over IC or BC treatment. In addition, non-smokers benefit more from IBC compared with IC. The occurrence of adverse events (AEs) was more frequent in IBC (74.3%) and IC (85.7%) group in relative to BC group (42.8%). Meanwhile, ≥ grade 3 AEs (22.9%) was markedly higher in IBC group compared with that in BC group (5.7%). However, leukopenia and neutropenia represent the most common ≥ grade 3 AEs, which are easy to be clinically managed. Conclusions: For metastatic lung adenocarcinoma patients with low PD-L1 expression, IBC is the preferred first-line therapy in terms of survival. However, the AEs should be carefully concerned.