Contrast-enhanced CT parameters predict short-term tumor response in patients with hepatocellular carcinoma who received sequential combined anti-angiogenesis and immune checkpoint inhibitor treatment.

Purpose: To evaluate whether relative Hounsfield unit attenuation index (rHUAI) on contrast-enhanced computed tomography (CECT) can predict tumor response in advanced hepatocellular carcinoma (HCC) patients who received sequential combined treatment of immune checkpoint inhibitor (ICI) and anti-angiogenesis therapy.

Method: One hundred seventeen advanced HCC patients who underwent the sequential combined treatment in a tertiary hospital between March 2020 and December 2021 were allocated to prediction and validation cohorts (with a ratio of 2:1) based on the time of initial ICI treatment. rHUAI from the arterial to the portal-venous phase (rHU_ap) and from the portal-venous to the delayed phase (rHU_pd) was calculated. The optimal cut-off values (COVs) of rHU_ap and rHU_pd for predicting tumor response were identified using Youden's index. Univariate and multivariable analyses were performed to assess the relationship between the COVs and tumor response. The validity of COVs was verified in the validation cohort using the chi-square test and Cramer's V coefficient (V).

Results: The optimal COVs of the two observers were 0.5316 and 0.3265 for rHU_ap, and -0.0208 and -0.0048 for rHU_pd, respectively. Multivariable analysis suggested that the COVs were independently associated with tumor response in the prediction cohort (rHU_ap, Odds ratio: 7.727 and 7.808, 95 % CI: 2.516-23.728 and 2.399-25.410, p value < 0.001 and 0.001; rHU_pd, Odds ratio: 0.034 and 0.011, 95 % CI: 0.002-0.600 and 0.001-0.209, p value of 0.021 and 0.003). In the validation cohort, the optimal COVs of rHU_ap had a moderate to a strong association with tumor response (V = 0.362-0.545, p < 0.05). The association between COVs of rHU_pd and tumor response was slight to strong (V = 0.24-0.545, p = 0.001 to 0.134).

Conclusion: rHUAI obtained from CECT has the potential as a non-invasive tool for predicting tumor response in advanced HCC patients who have received combined ICI and anti-angiogenesis treatment.