Response to platinum-based therapies in second-line after immunotherapy in advanced or metastatic non-small-cell lung cancer PD-L1 ≥50.

Background: Platinum-based therapies for patients with advanced non-small-cell lung cancer (NSCLC) have classically provided overall survival (OS) rates of six to nine months and objective response rates (ORRs) of 20-30%. Whether prior immunotherapy determines a different response to platinum is currently unknown. This study aimed to analyse the current response characteristics to platinum as a second-line treatment for advanced NSCLC (PD-L1 ≥50%) after first-line immunotherapy.

Methods: This retrospective study was conducted at the University Hospital of Salamanca (CAUSA) between 2016 and 2023 with patients who had advanced NSCLC (PD-L1 ≥50%) treated with second-line platinum-based therapies after immunotherapy (without mutations in EGFR, ALK or ROS1 and with Eastern Cooperative Oncology Group (ECOG) ≤1 during the first- and second-line treatments). Survival and response correlation analyses (Kaplan-Meier and log rank tests in SPSS v. 25) were performed. Subsequently, the results were compared with historical cohorts (PubMed, COCHRANE, ScienceDirect, Embase, and the clinical trial registry) who had received platinum-based therapies for advanced NSCLC.

Results: Seventeen patients were analysed (11 male and 6 female). Their median age was 67 years (interquartile range, 50-77 years). Fifteen patients (88.2%) were smokers or former smokers. The patients' main histology was adenocarcinoma (9 patients, 52.9%). All first-line treatments applied pembrolizumab (median dose: 12 cycles). Second-line platinum-based therapy achieved OS of 25 months (95% CI: 7-45 months) and progression-free survival (PFS) of 6 months (95% CI: 2.5-95 months). The ORR was 47.1% [seven patients with a partial response (PR) and one patient with a complete response (CR)]. Of the patients with PRs or CRs, 75% were treated with platinum plus pemetrexed. The one-year survival rate was 58.8%. The historical OS for first-line platinum-based doublets is 7 to 12 months, with PFS of three to five months and an ORR of 17-30%.

Conclusions: The current response to second-line platinum-based therapies for patients with advanced NSCLC after immunotherapy appears to achieve favourable response rates and be an optimal treatment after progression to immunotherapy. Prior immunotherapy appears to enhance these patients' platinum response, though future confirmatory studies are necessary.