Outcomes of First-Line Anti-PD-L1 Blockades Combined with Brain Radiotherapy (BRT) for Extensive-Stage Small-Cell Lung Cancer (ES-SCLC) with Brain Metastases (BM)

Abstract

<h3>Purpose/Objective(s)</h3> SCLC has a high incidence of BM and approximately 40%-50% of patients with SCLC will develop BM throughout disease course. BRT plays an important role in the management of BM. But whether the addition of anti-PD-L1 blockades brings additional benefits remains uncertain. The aim of the retrospective study is to investigate the clinical efficacy of the first-line anti-PD-L1 blockades combined with BRT in ES-SCLC with BM and further compare the incidence of leukoencephalopathy related to BRT. <h3>Materials/Methods</h3> Patients with newly diagnosed ES-SCLC and baseline BM confirmed by CT or MRI at Shandong Cancer Hospital and Research Institute between 2017 and 2021 were enrolled. Patients were assigned to the anti-PD-L1+BRT group and BRT group based on whether combined with anti-PD-L1 blockades (atezolizumab or durvalumab) or not. Responses were assessed according to RECIST 1.1. Survival analyses were performed using Kaplan-Meier and log-rank tests. Leukoencephalopathy was estimated by Fazekas grade. <h3>Results</h3> A total of 46 patients were enrolled in this study. Fifteen were assigned to anti-PD-L1+BRT group and 31 to BRT group. The median follow-up time was 18.23 months. Overall response rate (ORR) in the two groups was 73.33% vs 77.42% (<i>P</i> = 0.949) and disease control rate (DCR) was both 100%. Intracranial ORR and DCR were 53.33% vs 70.97% (<i>P</i> = 0.239) and 73.33% vs 80.65% (P = 0.855), respectively. Progression-free survival (PFS) was numerically prolonged with anti-PD-L1 blockades, but the significance was not reached (median: 9.40m vs 7.40m, <i>P</i> =0.362, HR=0.73 (95%CI, 0.38-1.40)). The median intracranial PFS was 8.23m vs 8.90m (<i>P</i>=0.620, HR=1.20 (0.57-2.55)). Overall survival (OS) was not improved, neither (median: NR vs 15.90m, <i>P</i>=0.17, HR=0.45 (0.18-1.10)). There was no significant difference in leukoencephalopathy between the two groups. The incidence of any grade and grade ≥3 leukoencephalopathy was 55.56% vs 54.55% (<i>P</i>=0.999) and 22.22% vs 27.27% (<i>P</i>=0.999) in the two groups, respectively. <h3>Conclusion</h3> For ES-SCLC with BM, without increasing cranial neurotoxicity, the combination of first-line anti-PD-L1 blockades with BRT did not confer a significant survival benefit compared with BRT alone.