2004P PD-L1 Inhibitors combined with whole brain radiotherapy in patients with small cell lung cancer brain metastases: Real-world evidence

Numerous studies have demonstrated that brain metastases (BMs) patients may benefit from intracranial radiotherapy combined with immune checkpoint inhibitors (ICIs). However, it is unclear whether this treatment is effective for patients with small cell lung cancer brain metastases (SCLC-BMs). We conducted a retrospective study by analyzing medical records of patients with SCLC-BMs from January 1, 2017 to June 1, 2022. Data related to overall survival (OS), progression-free survival (PFS), and intracranial progression-free survival (iPFS) were analyzed. There were 109 patients enrolled, of whom 60 received WBRT and 49 received WBRT-ICI. Compared to the WBRT alone cohort, the WBRT-ICI cohort showed longer OS (20.4 months vs 29.3 months, P=0.021), PFS (7.9 months vs 15.1 months, P<0.001), and iPFS (8.3 months vs 16.5 months, P<0.001). Patients receiving WBRT-ICI regimen had a better response rate for both brain metastases (p=0.035) and extracranial diseases (p=0.000) compared to those on WBRT alone. Using WBRT before ICI was associated with superior OS compared to that obtained after ICI (23.3 months for the before group vs 34.8 months for the after group, P=0.020). Our results indicated that WBRT combined with immunotherapy can improve survival in SCLC-BMs patients. The most optimal timing of WBRT is applying it before ICI, which can help improve OS. These findings highlight the significance of further prospective studies on intracranial radiotherapy and ICI combining strategies in SCLC-BM patients.