Single-fraction or multi-fraction stereotactic ablative body radiotherapy followed by atezolizumab in advanced triple-negative breast cancer: a randomized phase II trial

Abstract

Pre-clinical evidence suggests that stereotactic ablative body radiotherapy (SABR) can enhance systemic anti-tumor responses when combined with immune checkpoint inhibition, although optimal fractionation remains uncertain. Here we conducted a phase II multi-center randomized trial (AZTEC trial; ClinicalTrials.gov identifier NCT03464942) to investigate the efficacy and safety of single-fraction (SF: 20 Gy; n = 27) or multi-fraction (MF: 24 Gy in three fractions; n = 27) SABR followed by anti-PD-L1 atezolizumab in 54 women with advanced triple-negative breast cancer (TNBC) as first or second-line treatment. The primary endpoint was progression free survival (PFS). Secondary endpoints included..