Prospective study of blood-based tumor mutational burden as a biomarker for atezolizumab in NSCLC

Tumor mutational burden in circulating tumor DNA has shown promise in predicting benefit from PD-(L)1 inhibitors in retrospective studies. The multicenter phase 2 B-F1RST trial in the US evaluated blood tumor mutational burden (bTMB) as a predictive biomarker for first-line atezolizumab monotherapy for locally advanced or metastatic non-small cell lung cancer. The study showed that bTMB ≥ 16 (14.5 mut/Mb) was associated with higher ORR, and that ORR improved as bTMB cutoffs increased. At 36.5-month follow-up, an exploratory analysis of OS found that bTMB ≥ 16 was associated longer OS than bTMB < 16.