Case Presentation and Overview of IMpower133 in ES-SCLC

Patients with ES-SCLC face a challenging diagnosis, as illustrated by a typical case of a 63-year-old man with a 40-pack-year smoking history who developed a cough, chest tightness, and unintentional weight loss. His condition progressed to extensive stage disease with bilateral pulmonary nodules and liver metastases, representing the aggressive nature of this cancer type that affects thousands of patients annually.

The IMpower133 trial revolutionized treatment for patients with ES-SCLC by demonstrating that adding atezolizumab (a PD-L1 inhibitor) to standard carboplatin and etoposide chemotherapy significantly improves patient outcomes. Patients receiving this combination followed by maintenance atezolizumab lived longer, with median survival increasing from 10.3 months to 12.3 months compared with chemotherapy alone. This landmark achievement, published in 2018, marked the first improvement in survival for patients with this cancer type in nearly 40 years.

While atezolizumab plus chemotherapy became standard care for patients with ES-SCLC, the reality remains sobering: Most patients do not achieve long-term survival despite this advancement. Only a small subset of patients experiences durable benefit, with 5-year survival rates around 12%. Real-world studies confirm that these trial results apply broadly to patients with varying performance statuses and comorbidities such as chronic obstructive pulmonary disease, though identifying which patients will benefit most remains challenging due to a lack of reliable biomarkers.