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

Abstract

Background: Numerous studies have demonstrated that brain metastases 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).

Methods: 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 median overall survival (mOS), median progression-free survival (mPFS), and intracranial progression-free survival (iPFS) were analyzed.

Results: A total of 109 patients were enrolled, of which 60 received WBRT and 49 received WBRT-ICI. Compared to the WBRT alone cohort, the WBRT-ICI cohort showed longer mOS (20.4 months vs. 29.3 months, p = 0.021), mPFS (7.9 months vs. 15.1 months, p < 0.001), and iPFS (8.3 months vs. 16.5 months, p < 0.001). Furthermore, WBRT-ICI cohort had a better response rate for both BMs. (p = 0.035) and extracranial diseases (p < 0.001) compared to those receiving WBRT alone. Notably, the use of WBRT before ICI was associated with longer mOS compared to the use of WBRT after ICI (23.3 months for the ICI-WBRT group vs. 34.8 months for the WBRT-ICI group, p = 0.020).

Conclusion: Our results indicated that WBRT combined with immunotherapy improved survival in SCLC-BMs patients compared to WBRT monotherapy. Administering WBRT prior to ICI treatment is associated with improved survival outcomes compared to WBRT following ICI treatment, for patients with SCLC-BMs. These findings highlight the significance of conducting further prospective researches on combination strategies of intracranial radiotherapy and ICI in SCLC-BMs patients.

Keywords: extensive small cell lung cancer; immunotherapy; intracranial metastasis; radiotherapy.