Intracranial response pattern, tolerability and biomarkers associated with brain metastases in non-small cell lung cancer treated by tislelizumab plus chemotherapy.

Background:Programmed cell death protein-1/programmed cell death protein-ligand 1 (PD-1/PD-L1) inhibitor and chemotherapy are the standard treatment for advanced non-small cell lung cancer (NSCLC) without sensitizing mutations. However, patients with untreated, symptomatic or recently-irradiated brain metastases (BMs) are mostly excluded from immunochemotherapy trials. This study aims to evaluate the intracranial response pattern, tolerability and biomarkers of tislelizumab plus chemotherapy in NSCLC with untreated, symptomatic or recently-irradiated BM. Methods:This multicenter, single-arm, phase 2 trial enrolled patients with treatment-naïve, brain-metastasized NSCLC. BM could be untreated or irradiated. Symptomatic or recently-irradiated BMs that were deemed clinically stable were allowed. Patients received tislelizumab (200 mg) plus pemetrexed (500 mg/m2) and carboplatin (AUC =5) on day 1 every 3 weeks for 4 cycles, followed by maintenance with tislelizumab plus pemetrexed. Primary endpoint was 1-year progression-free survival (PFS) rate. Secondary endpoints included intracranial efficacy and tolerability. PD-L1 expression, tumor mutational burden (TMB) and genomic alterations were evaluated as potential biomarkers. Results:A total of 36 patients were enrolled, 19.2% had prior brain radiotherapy, 8.3% had symptomatic BMs that required corticosteroids ≤10 mg/d or antiepileptics. Confirmed systemic and intracranial ORR (iORR) was 43.8% and 46.7%, respectively. One-year systematic PFS rate and One-year iPFS rate was 36.8% and 55.8%, respectively. About 41.7% patients had neurological adverse events, 90% patients had concordant intracranial-extracranial responses. No intracranial pseudoprogression or hyperprogression occurred. Patients with prior brain radiation trended towards higher systemic (83.3% vs. 34.6%) and iORR (75.0% vs. 42.3%). Similar intracranial efficacy was observed in tumors with different PD-L1 and TMB levels, while alterations in cytokine receptors pathway predicted higher iORR (P=0.081), prolonged systematic PFS [hazard ratio (HR) =0.16, P=0.021] and overall survival (OS) (HR =0.71, P=0.029). Conclusions:Untreated or irradiated BMs in NSCLC follows a conventional response and progression pattern under immunochemotherapy with altered cytokine receptors pathway being a potential biomarker for systemic and intracranial outcomes.