Induction Immune Checkpoint Inhibitors and Chemotherapy Before Definitive Chemoradiation Therapy for Patients With Bulky Unresectable Stage III Non-Small Cell Lung Cancer

Purpose In the era of immunotherapy, the treatment for bulky, locally advanced non-small cell lung cancer (LA-NSCLC) remains challenging. This study explored the feasibility of induction immune checkpoint inhibitors (ICIs) plus chemotherapy before definitive chemoradiation therapy (CRT) for bulky LA-NSCLC. Methods and Materials Patients with bulky, unresectable stage III NSCLC (primary tumor ≥5 cm in greatest dimension or metastatic lymph nodes ≥2 cm in shortest diameter) receiving ICIs and chemotherapy before CRT from 2018 to 2022 were identified. Survival outcomes and toxic effects were analyzed. Radiation therapy plans on computed tomography images before and after 2 cycles of induction chemoimmunotherapy were simulated to evaluate dosimetric outcomes. Results Seventy-five patients were included. One- and 2-year overall-survival (OS) rates were 91.5% (95% CI, 85.2%-98.3%) and 75.1% (95% CI, 64.1%-88.0%), respectively. One- and 2-year progression-free-survival (PFS) rates were 85.8% (95% CI, 78.0%-94.4%) and 64.2% (95% CI, 52.5%-78.6%), respectively. Median OS was not reached (NR). Median PFS was 30.6 months (95% CI, 25.9 months to NR). Grade 2 and ≥3 pneumonitis occurred in 26.7% and 9.3% of patients, respectively. Grade ≥3 pneumonitis was significantly associated with poorer OS (P = .003) and PFS (P = .018). Treatment discontinuation was significantly associated with shorter OS (P = .023) and PFS (P = .047). Patients with consolidation ICIs exhibited numerically better OS than those without consolidation ICIs (2-year OS, 85.8% vs 64.2%; P = .170). The objective response rate was 76.1% for induction treatment and 86.7% for induction treatment plus CRT. The disease control rate after 2 cycles of induction therapy was significantly greater than after 4 (P = .046) or more cycles (P = .025). Simulated radiation plans indicated that all target volumes, mean lung dose, and volume of lung parenchyma receiving ≥5 Gy, ≥20 Gy, and ≥30 Gy significantly decreased after 2 cycles (all P < .005). Conclusions Two cycles of induction ICIs plus chemotherapy before definitive CRT were feasible for bulky LA-NSCLC, with significant tumor reduction and normal lung protection. Further investigations on CRT combined with induction and consolidation ICIs are warranted. In the era of immunotherapy, the treatment for bulky, locally advanced non-small cell lung cancer (LA-NSCLC) remains challenging. This study explored the feasibility of induction immune checkpoint inhibitors (ICIs) plus chemotherapy before definitive chemoradiation therapy (CRT) for bulky LA-NSCLC. Patients with bulky, unresectable stage III NSCLC (primary tumor ≥5 cm in greatest dimension or metastatic lymph nodes ≥2 cm in shortest diameter) receiving ICIs and chemotherapy before CRT from 2018 to 2022 were identified. Survival outcomes and toxic effects were analyzed. Radiation therapy plans on computed tomography images before and after 2 cycles of induction chemoimmunotherapy were simulated to evaluate dosimetric outcomes. Seventy-five patients were included. One- and 2-year overall-survival (OS) rates were 91.5% (95% CI, 85.2%-98.3%) and 75.1% (95% CI, 64.1%-88.0%), respectively. One- and 2-year progression-free-survival (PFS) rates were 85.8% (95% CI, 78.0%-94.4%) and 64.2% (95% CI, 52.5%-78.6%), respectively. Median OS was not reached (NR). Median PFS was 30.6 months (95% CI, 25.9 months to NR). Grade 2 and ≥3 pneumonitis occurred in 26.7% and 9.3% of patients, respectively. Grade ≥3 pneumonitis was significantly associated with poorer OS (P = .003) and PFS (P = .018). Treatment discontinuation was significantly associated with shorter OS (P = .023) and PFS (P = .047). Patients with consolidation ICIs exhibited numerically better OS than those without consolidation ICIs (2-year OS, 85.8% vs 64.2%; P = .170). The objective response rate was 76.1% for induction treatment and 86.7% for induction treatment plus CRT. The disease control rate after 2 cycles of induction therapy was significantly greater than after 4 (P = .046) or more cycles (P = .025). Simulated radiation plans indicated that all target volumes, mean lung dose, and volume of lung parenchyma receiving ≥5 Gy, ≥20 Gy, and ≥30 Gy significantly decreased after 2 cycles (all P < .005). Two cycles of induction ICIs plus chemotherapy before definitive CRT were feasible for bulky LA-NSCLC, with significant tumor reduction and normal lung protection. Further investigations on CRT combined with induction and consolidation ICIs are warranted.