The clinical outcome and risk factors analysis of immune checkpoint inhibitor-based treatment in lung adenocarcinoma patients with brain metastases.

Background: The data about efficacy of immunotherapy for non-small cell lung cancer with brain metastases (BMs) from real-word settings are controversial. This real-word study is aimed to evaluate the clinical outcome of immune checkpoint inhibitor (ICI)-based treatment in lung adenocarcinoma patients with brain metastases (BMs) and explore potential risk factors, with a focus on the spatial distribution of BMs as previous studies suggested spatial heterogeneity on the brain immune microenvironment.

Methods: Advanced lung adenocarcinoma patients with non-oncogene-addicted, who received ICI monotherapy or plus chemotherapy, were enrolled. Efficacy was assessed by Response Evaluation Criteria in Solid Tumors version 1.1. Intergroup comparisons were performed using Pearson's χ or Fisher's exact tests for categorical variables. The progression-free survival (PFS) was estimated using Kaplan-Meier method and compared using log-rank test. Cox proportional hazards model was used for multivariate analyses. Peripheral blood was collected from 15 patients with BMs. Tumor-derived exosomes in plasma were isolated by size exclusion chromatography and the cDNA library preparations for miRNA were sequenced on an Illumina Hiseq platform. Differentially expressed genes in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed.

Results: A total of 198 patients were enrolled and brain metastasis occurred in 20.7% patients (N=41). Compared with patients without BMs, those with BMs had a comparable objective response rate (ORR; 29.3% 43.9%; P=0.089), a lower disease control rate (DCR; 58.5% 78.3%; P=0.01), and a shorter PFS (3.6 8.6 months; P=0.069). For patients with BMs, factors, including the presence of neurological symptoms, the treatment of intracranial radiotherapy, and the combination of ICI with chemotherapy, had no impact on PFS, whereas cerebellum metastasis was significantly associated with shorter PFS (2.8 13.8 months, P=0.007). Six upregulated miRNAs were identified in patients with cerebellum metastases (N=8) compared with those without (N=7). The enrichment of differentially expression genes in the KEGG pathways indicated upregulated sulfur metabolism pathway in patients with cerebellum metastases.

Conclusions: For lung adenocarcinoma patients, those with BMs have inferior response to ICI-based treatment, but not significantly, and cerebellum metastasis is an independent risk factor with poor outcome for such patients, might attributing to the upregulated sulfur metabolism.