A retrospective study of induction immunochemotherapy followed by definitive chemoradiotherapy and consolidation immunotherapy in unresectable locally advanced non-small cell lung cancer.

8076 Background: The standard treatment for patients with unresectable stage III non-small cell lung cancer (NSCLC) involves concurrent chemoradiotherapy (cCRT) followed by one year of durvalumab consolidation therapy. Numerous clinical studies have sought to optimize this treatment paradigm to enhance clinical outcomes. In this retrospective real-world study, we evaluated the efficacy and safety of the addition of induction chemoimmunotherapy prior to the PACIFIC regimen compared with the standard PACIFIC regimen. The aim was to determine whether introducing immunotherapy earlier into the treatment strategy for unresectable stage III NSCLC could improve disease control rates. Methods: This study included patients with unresectable stage III NSCLC. Patients received either induction chemoimmunotherapy followed by cCRT or sequential chemoradiotherapy (sCRT) with consolidation immunotherapy, or cCRT/sCRT directly followed by consolidation immunotherapy. The primary endpoint was progression-free survival (PFS), defined as the time from the initiation of consolidation immunotherapy to disease progression or death. The incidence of radiation-induced immune pneumonitis was also assessed between the two groups. Results: A total of 210 patients with unresectable stage III NSCLC were included in this study, enrolled between July 2019 and April 2023. Among them, 76 patients received induction chemoimmunotherapy, and 134 patients were treated without induction chemoimmunotherapy. Baseline characteristics between the two groups showed no significant differences. The proportion of patients receiving cCRT in the induction chemoimmunotherapy group and the non-induction chemoimmunotherapy group was 29/76 (38.1%) and 110/134 (82.1%), respectively. Within each group, there was no statistically significant difference in progression-free survival (PFS) between patients treated with cCRT or sCRT. The induction chemoimmunotherapy group demonstrated superior median PFS (mPFS) compared to the non-induction chemoimmunotherapy group (not reached vs. 17.2 months, P=0.01). Overall survival (OS) data remain immature for analysis. The incidence of pneumonitis was observed in 52/76 (68.4%) patients in the induction chemoimmunotherapy group, with ≥Grade 2 pneumonitis occurring in 18/76 (23.7%) patients. In the non-induction chemoimmunotherapy group, pneumonitis occurred in 86/134 (64.2%) patients, with ≥Grade 2 pneumonitis in 30/134 (22.4%) patients. No significant differences in pneumonitis incidence or severity were observed between the two groups. Conclusions: The addition of induction chemoimmunotherapy prior to the PACIFIC regimen demonstrated improved disease control rates compared to the standard approach, with no increased risk of pneumonitis.