e20556 Background: The subsequent therapy of elderly non-small cell lung cancer (NSCLC) without driver oncogene has always been a challenge due to the poor performance status and multiple comorbidities, especially in those who acquired resistance to programmed cell death protein 1/programmed death-ligand 1 [PD-(L)1] blockade. Metronomic chemotherapy (MCT) is the frequent administration of chemotherapy drugs at lower doses each time which shows a better safety profile, antitumor angiogenesis, and immune modulatory effects compared with traditional chemotherapy. Here we designed an observational study to evaluate the efficacy and safety of PD-1 inhibitors plus metronomic oral vinorelbine(mOV) in elderly pre-treated metastatic NSCLC. Methods: Patients aged 65 years and above who had been histologically or cytologically confirmed unresectable stage III and IV NSCLC were recruited for this study. All the pts had no EGFR mutation, ALK fusions, or ROS1 fusions and received at least one systematic treatment. Pts received PD-1 inhibitors combined with mOV (30mg, TIW1, day 1-3-5 per week) for 6 cycles, followed by PD-1 inhibitors maintenance until disease progression or intolerable toxicities. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), objective response rate (ORR), disease control rate (DCR), and safety. Results: From May 2020 to June 2023, 23 pts were enrolled in the study. The median age was 70 with 18(78%) males. Median follow-up time was 22.8 months (range 3.9months-41.9months). The median PFS was 5.13 months (95%Cl: 3.1 months-7.1 months) and the median OS was 28.1 months (95%Cl: (15.2 months-NA). The ORR and DCR were 13% (95%C1: 1.44%-27.6%) and 69.6% (95%Cl: 49.2%-89.9%), respectively. The PFS (p = 0.459, HR = 0.671 95%CI 0.233-1.932) and OS (p = 0.483, HR = 1.607 95%CI 0.426-6.056) were similar between those pts who previously received immunotherapy (N = 16, 69.5%) and not. PD-L1 TPS didn’t affect the patient’s PFS (<1% vs≥1%, p = 0.078, HR = 2.648 95%CI 0.895-7.835 ) and OS(<1% vs≥1%, p = 0.306, HR = 2.202 95%CI 0.485-9.989). Adverse events (AEs) of any grade were observed in 20(86.9%) pts of which grade III-IV AEs occurred in 4 (17.4%) pts. These grade III-IV events consisted of interstitial pneumonia, pulmonary infection, leukopenia, and neutropenia. Immune-related adverse events (irAEs) occurred in 4 (17.4%) pts, of which grade III irAEs occurred in 2 (8.7%) patients with interstitial pneumonia. No grade 4 irAEs and grade 5 adverse events even occurred. Conclusions: The regimen of PD-1 inhibitors plus mOV for the subsequent therapy showed good overall survival benefits and safety in elderly patients with metastatic NSCLC without driver oncogene which suggests it is worth further exploration.
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