1299P - The role of radiotherapy in extensive-stage small cell lung cancer after durvalumab-based immunochemotherapy: A retrospective study

Background

The purpose of this study was to evaluate the safety and efficacy of subsequent radiotherapy after first-line durvalumab plus chemotherapy in extensive-stage small cell lung cancer (ES-SCLC).

Methods

A total of 122 patients with ES-SCLC from three hospitals during July 2019 to December 2021 were retrospectively analyzed. Inverse probability of treatment weighting (IPTW) analysis was performed to address potential confounding factors. We primarily evaluated the progression-free survival (PFS) and overall survival (OS) in association with radiotherapy.

Results

After IPTW analysis, 49 patients received durvalumab plus chemotherapy with subsequent radiotherapy (Durva+EP+RT) and 72 patients received immunochemotherapy (Durva+EP). The median OS was 17.2 vs 12.3 months (hazard ratio (HR): 0.38; P=0.020), respectively, and the median PFS was 8.9 vs 5.9 months (HR: 0.56; P=0.030), respectively. Thoracic radiation therapy (TRT) resulted in longer OS (17.2 vs 14.7 months) and PFS (9.1 vs 7.2 months) compared to radiotherapy directed to other metastatic sites. Among patients with oligo-metastasis, radiotherapy also showed significant benefits, with a median OS of 17.4 vs 13.7 months and median PFS of 9.8 vs 5.9 months compared to no radiotherapy. Continuous durvalumab treatment beyond progression (TBP) prolonged OS compared to patients without TBP, in both the Durva+EP+RT (NA vs 15.8 months, HR: 0.48) and Durva+EP groups (12.3 vs 4.3 months, HR: 0.29). Grade 3 or 4 adverse events occurred in 13 (26.5%) and 13 (18.1%) patients, respectively, in the two groups; pneumonitis was mostly low-grade.

Conclusions

Addition of radiotherapy after first-line immunochemotherapy significantly improved survival outcomes with manageable toxicity in ES-SCLC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Bethune-Cancer Radiotherapy Translational Medicine Research Fund of China.

Disclosure

All authors have declared no conflicts of interest.