Efficacy and safety of durvalumab + chemotherapy vs. atezolizumab + chemotherapy in the treatment of small­cell lung cancer: a retrospective comparative cohort study.

Background: Durvalumab and atezolizumab have recently been approved in extensive small cell lung cancer (SCLC) with moderate median overall survival (OS) improvements. However, only limited data exist regarding the impact of immunotherapy in real-world SCLC patients. This study sought to assess the efficacy and safety of atezolizumab plus chemotherapy and durvalumab plus chemotherapy in the treatment of SCLC in a real-world setting. Methods: A retrospective cohort study of all patients treated for SCLC with chemotherapy with PD-L1 inhibitor, at 3 centers in China between February 1, 2020 and April 30, 2022. Patient characteristics, adverse-events and survival analyses were conducted. Results: A total of 143 patients were enrolled in this study, 100 were treated with durvalumab and the remainder with atezolizumab. The baseline characteristics of the two groups were fundamentally balanced before using PD-L1 inhibitors (P>0.05). The median OS (mOS) of the patients who received durvalumab or atezolizumab as the first-line treatment were 22.0 and 10.0 months, respectively (P=0.03). Survival analysis of patients with brain metastasis (BM) revealed that the median progression-free survival (mPFS) of patients without BM treated with durvalumab plus chemotherapy (5.5 months) was longer than that of those with BM (4.0 months) (P=0.03). In contrast, in the atezolizumab plus chemotherapy regimen, BM did not affect survival. In addition, the addition of radiotherapy to treatment with PD-L1 inhibitors in combination with chemotherapy has a tendency to improve long-term survival. As for safety analysis, there was no significant difference in the incidence of immune-related adverse events (IRAEs) during PD-L1 inhibitor therapy between the 2 groups (P>0.05). And during treatment with immunochemotherapy, radiotherapy was not associated with the development of IRAE (P=0.42) but increased the risk of immune-related pneumonitis (P=0.026). Conclusions: The implication of this study for clinical practice is a preference for durvalumab in first-line immunotherapy for SCLC. In addition, appropriate radiotherapy during treatment with PD-L1 inhibitors in combination with chemotherapy may prolong long-term survival, but the occurrence of immune-related pneumonitis should be vigilant. Data from this study are limited and the baseline characteristics of the two populations still need to be more finely classified.