Impact of timing of immunotherapy in survival among patients with advanced lung adenocarcinoma treated with first-line immunochemotherapy: A propensity score matching.

e20560 Background: Immunochemotherapy combinations have been the mainstream first-line standard treatment of advanced non-small cell lung cancer (NSCLC), wherein concurrent chemotherapy and immunotherapy are conventionally fixed to an established dosing regimen. Few studies had suggested the remarkable impact of the timing of immunotherapy on immunochemotherapy combined therapy. However, this issue has not been addressed in advanced NSCLC cohort. Methods: This study was a retrospective analysis of 532 patients with advanced lung adenocarcinoma (LUAD) without EGFR/ALK mutations who underwent immunochemotherapy as first-line systemic treatment between June 2018 to June 2022 at 3 facilities. Patients were divided into two groups (induced and non-induced) according to the different timing of immunotherapy in combined therapy, which defined induced as receiving 1 or more cycles of full-dose chemotherapy alone before concurrent immunochemotherapy. The bias between induced and non-induced groups was minimized with Propensity Score Matching (PSM). Patients outcomes, including progression-free survival (PFS) and overall survival (OS), were compared between the two groups by Kaplan-Meier survival curves and Cox regression analyses. Results: Survival analysis showed that both PFS and OS of the induced chemotherapy group patients were significantly longer than that of non-induced group (PFS: 14.63 months vs. 10.13 months, p = 0.004; OS: Not reached vs. 20.27 months, p = 0.0013). In the COX regression, after adjusting for confounders, induction chemotherapy was found to be a remarkable favorable factor for both PFS and OS (PFS: HR = 0.73, p= 0.018; OS: HR = 0.69, p= 0.034). After pretreatment features and treatment parameters were included in PSM, 104 patients were identified in each groups with matched characteristics, and moreover, the results of survival analysis remained consistent and showed significant difference between induced and non-induced group (PFS: 14.63 months vs. 10.23 months, p = 0.029; HR = 0.71, p= 0.030. OS: Not reached vs 18.27 months, p = 0.0013; HR = 0.52, p= 0.002). Conclusions: For advanced LUAD patients treated with first-line immunochemotherapy combinations, the timing of immunotherapy had significant impact on prognosis, which suggested notable benefit of induction chemotherapy before concurrent immunochemotherapy.