ctDNA-adjusted bTMB as a predictive biomarker for patients with NSCLC treated with PD-(L)1 inhibitors
Wei Nie, Zhijie Wang, Kai Zhang, Bing Li, Yiran Cai, Fengcai Wen, Ding Zhang, Yuezong Bai, Xueyan Zhang, Shuyuan Wang, Lei Cheng, Hua Zhong, Li Liu, Jie Wang, Baohui Han
Abstract
BACKGROUND: In non-small cell lung cancer (NSCLC) patients receiving immune checkpoint inhibitors (ICIs), higher blood tumor mutational burden (bTMB) was usually associated with better progression-free survival (PFS) and objective response rate (ORR). However, the association between bTMB and overall survival (OS) benefit remains undefined. It has been reported that patients harboring a high level of circulating tumor DNA (ctDNA) had poor survival. We hypothesized that ctDNA-adjusted bTMB might predict OS benefit in NSCLC patients receiving ICIs. METHODS: Our study was retrospectively performed in three cohorts, including OAK and POPLAR cohort (n = 853), Shanghai and Wuhan (SH&WH) cohort (n = 44), and National Cancer Center (NCC) cohort (n = 47). Durable clinical benefit (DCB) was defined as PFS lasting ≥ 6 months. The cutoff value of ctDNA-adjusted bTMB for DCB prediction was calculated based on a receiver operating characteristic curve. Interaction between treatments and ctDNA-adjusted bTMB was assessed. RESULTS: The bTMB score was significantly associated with tumor burden, while no association was observed between ctDNA-adjusted bTMB with tumor burden. In the OAK and POPLAR cohort, significantly higher ORR (P = 0.020) and DCB (P < 0.001) were observed in patients with high ctDNA-adjusted bTMB than those with low ctDNA-adjusted bTMB. Importantly, the interactions between ctDNA-adjusted bTMB and treatments were significant for OS (interaction P = 0.019) and PFS (interaction P = 0.002). In the SH&WH cohort, the interactions between ctDNA-adjusted bTMB and treatment were marginally significant for OS (interaction P = 0.081) and PFS (interaction P = 0.062). Similar result was demonstrated in the NCC cohort. CONCLUSIONS: Our study indicated that ctDNA-adjusted bTMB might predict OS benefit in NSCLC patients receiving ICIs. The potential of ctDNA-adjusted bTMB as a noninvasive predictor for immunotherapy should be confirmed in future studies.