Functional cure of hepatitis B in patients with cancer undergoing immune checkpoint inhibitor therapy

Background & Aims: Immune checkpoint inhibitors (ICIs) can restore exhausted T-cell immunity not only for cancer treatment but also potentially to cure chronic hepatitis B (CHB). Thus, we aimed to determine the previously unclear impact of ICIs on hepatitis B surface antigen (HBsAg) seroclearance in patients with cancer. Methods: Consecutive patients with cancer from 2016 to 2020 (cohort 1, n = 118), and hepatocellular carcinoma from 2020 to 2022 (cohort 2, n = 44, as validation) receiving ICIs and positive for HBsAg were retrospectively recruited. An additional HBV-HCC cohort (cohort 3, n = 85) not receiving ICIs served as a control group. Factors associated with HBsAg loss or a HBsAg decline >1 log were analyzed. Results: With median follow-up of 17.5 months, 8 (6.8%) patients in cohort 1 and 4 (9.1%) in cohort 2 achieved HBsAg seroclearance, and an additional four in cohort 1 and one in cohort 2 had a HBsAg decline >1 log. In multivariate analysis, HBsAg <100 IU/ml was associated with HBsAg seroclearance (hazard ratio 6.274, p = 0.028). In the validation cohort, the cumulative incidences of HBsAg loss at months 12 and 24 were 13.0% and 38.4%, respectively, for baseline HBsAg <100 IU/ml, which were significantly higher than those in the control group (p = 0.0267). No case in cohort 3 achieved HBsAg loss within 24 months. Of the 17 cases who achieved HBsAg loss or a decline >1 log, 16 (94.1%) received nucleos(t)ide analogue treatment. The median time to HBsAg loss or HBsAg decline was 16.5 (range 9.6 to 27.5) months. Conclusions: ICIs may accelerate HBsAg seroclearance in patients with cancer and baseline HBsAg <100 IU/ml. This finding provides important information for the design of future trials evaluating the ability of ICIs to induce functional cure in patients with CHB. Impact and implications: Immune checkpoint inhibitors (ICIs) can restore exhausted T-cell immunity not only for cancer treatment but also potentially to cure chronic hepatitis B. Functional cure of hepatitis B was observed in patients with cancer or HCC undergoing ICI treatment, and the cumulative incidence of HBsAg loss was higher compared with controls without ICIs. ICIs may accelerate the HBsAg loss in patients with baseline HBsAg levels <100 IU/ml. This finding provides important information for the design of future ICI trials evaluating the ability of ICIs to induce functional cure in patients with CHB.