Trajectories of α-fetoprotein and Unresectable Hepatocellular Carcinoma Outcomes Receiving Atezolizumab Plus Bevacizumab: a Secondary Analysis of IMbrave150 Study

Background: α-fetoprotein (AFP) response has been demonstrated as a biomarker for unresectable hepatocellular carcinoma (uHCC) patients receiving immunotherapy, but its definition is still unclear. This exploratory study investigated the AFP trajectory and clinical outcomes of receiving atezolizumab plus bevacizumab (Atez/Bev) therapy.

Methods: This secondary analysis used the Atez/Bev arm data of phase III IMbrave150 study to distinguish potential AFP changing rate trajectories through latent class trajectory models. The multivariable Cox models were applied to calculate adjusted hazard ratios (HRs) and 95% CIs for clinical outcomes.

Results: Three distinct trajectories were identified among the uHCC patients with 7 times (range, 3 to 28) of AFP measurements: low-stable (50.0%, n = 132), sharp-falling (13.3%, n = 35), and high-rising (36.7%, n = 97). Compared with the high-rising class, HRs of disease progression were 0.52 (95% CI: 0.39, 0.70) and 0.26 (95% CI: 0.16, 0.43) for the low-stable class and sharp-falling class, respectively. In contrast, HRs of death were 0.59 (95% CI: 0.40, 0.81) and 0.30 (95% CI: 0.16, 0.57) for the two groups after propensity score adjustment. Besides, AFP trajectories had the highest relative importance of each covariate to survival.

Discussion: There are three distinct AFP trajectories in uHCC patients receiving Atez/Bev, and it is an independent biomarker for clinical outcomes.