Atezolizumab in the first-line treatment of small cell lung cancer: Toxicity and safety in real-world clinical practice

Introduction . Small cell lung cancer (SCLC) accounts for approximately 15–20% of all lung cancer cases. The addition of PD-L1 inhibitors to platinum-etoposide chemotherapy has become the standard of care first-line treatment of SCLC. IMpower133 study revealed that immune-related adverse events (irAEs) were observed in 33.3% of patients, with only 4% of cases discontinuing treatment owing to irAEs, which indicates an acceptable safety profile. Aim . To analyse the toxicity profile of atezolizumab in combination with chemotherapy in the first-line treatment of patients with small cell lung cancer in real-world clinical practice. Materials and methods . This prospective/retrospective, non-randomized, single-site study included 157 patients aged 32 to 84 years with advanced SCLC, who received atezolizumab + carboplatin/cisplatin + etoposide as first-line chemoimmunotherapy over the 2019 to 2025 period at the S. S. Yudin City Clinical Hospital. 101 (65.6%) patients showed a satisfactory ECOG performance status (ECOG 0-1), whereas 54 (34.4%) patients showed ECOG PS of 2-3. Results . Grade 3-4 irAEs were diagnosed in 8 patients (5.1%). 14 patients (8.92%) were assigned to receive systemic glucocorticosteroid therapy. Five (3.18%) patients required complete discontinuation of immunotherapy due to immune-related toxicity. Conclusions . In real-world clinical practice, the combination of atezolizumab and chemotherapy demonstrated an acceptable and manageable toxicity profile, even when used in patients with a baseline reduced performance status and aggravated medical history.