Effectiveness and Safety of Immune Checkpoint Inhibitors Alone or in Combination With Chemotherapy in Pulmonary Sarcomatoid Carcinoma.

Introduction: Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of lung cancer associated with poor prognosis and resistance to conventional chemotherapy. Immune checkpoint inhibitors (ICIs), alone or in combination with chemotherapy, were found to have clinical benefits in PSC in recent studies. Nevertheless, because these studies included a small number of patients owing to disease rarity, larger studies are needed to evaluate the effectiveness and safety of ICI-based therapy for PSC. Methods: This multicenter retrospective study evaluated patients with ICI-naive advanced or metastatic PSC who were treated with ICI-based therapy at 25 hospitals in Japan. Results: A total of 124 patients were evaluated. The overall response rate, median progression-free survival (PFS), and median overall survival (OS) were 59.0%, 10.5 months, and 32.8 months, respectively. The PFS and OS rates at 24 months were 35.3% and 51.5%, respectively. Programmed death-ligand 1 expression, concomitant chemotherapy, and the treatment line were not significantly associated with PFS or OS. Immune-related adverse events (irAEs) were observed in 70 patients (56.5%), including 30 (24.2%) with grade 3 to 5 events. Patients with mild irAEs (grades 1-2) had longer PFS and OS than did those with severe (grades 3-5) or no irAEs. In a multivariate analysis, any-grade irAEs and the absence of liver metastases were independently associated with PFS, whereas any-grade irAEs and Eastern Cooperative Oncology Group performance status less than or equal to 1 were independently associated with OS. Conclusions: ICI-based therapy was found to have promising effectiveness in patients with advanced or metastatic PSC, regardless of programmed death-ligand 1 expression, concomitant chemotherapy, or treatment line.