Continuous immunotherapy beyond progression in clinical practice for small cell lung cancer

In non-small-cell lung cancer, continuous immune-checkpoint inhibitors (ICIs) beyond progression are often used in clinical practice. On the other hand, there is almost no data on whether the concept of continuous ICIs beyond progression can be adopted in small-cell lung cancer (SCLC). We describe the effectiveness of continuous ICIs beyond progression in SCLC. Medical courses of SCLC patients treated with chemo-immunotherapy were retrospectively reviewed at our hospital. The study included 36 patients with a median age of 73 years (range 46-83 years) who introduced chemo-immunotherapy between September 2019 and December 2022. Atezolizumab and durvalumab in combination with platinum plus etoposide were administered in 24 and 12 patients, respectively. The overall response rate was 67% and the disease control rate was 86%. The median progression-free survival and time to treatment failure (TTF) were 5.1 and 10.3 months, respectively. The median cycle of ICIs was 5 (range 1-42). The median overall survival was 13.6 months. ICIs were administered beyond progression in 14 (39%) patients: five were treated again with chemo-immunotherapy and local ablative radiotherapy, four with local ablative radiotherapy and continuous ICIs, three with chemo-immunotherapy, and two with continuous ICIs alone. TTF exceeded 12 months in 12 (86%) of the 14 cases, six of which were still on ICIs. Adverse events ≥grade 3 were observed in 21 (58%) patients. A notable TTF suggested a benefit of continuous ICIs beyond progression. The concept could be suitably adopted and provide a favorable prognosis in selected cases of SCLC that were previously regarded as an aggressive malignancy.