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.

Human CLEC18 Gene Cluster Contains C-type Lectins with Differential Glycan-binding Specificity.

The human C-type lectin 18 (clec18) gene cluster, which contains three clec18a, clec18b, and clec18c loci, is located in human chromosome 16q22. Although the amino acid sequences of CLEC18A, CLEC18B, and CLEC18C are almost identical, several amino acid residues located in the C-type lectin-like domain (CTLD) and the sperm-coating protein/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS) domain, also known as the cysteine-rich secretory proteins/antigen 5/pathogenesis-related 1 proteins (CAP) domain, are distinct from each other. Genotyping by real-time PCR and sequencing further shows the presence of multiple alleles in clec18a/b/c loci. Flow cytometry analysis demonstrates that CLEC18 (CLEC18A, -B, and -C) are expressed abundantly in human peripheral blood cells. Moreover, CLEC18 expression is further up-regulated when monocytes differentiate into macrophages and dendritic cells. Immunofluorescence staining reveals that CLEC18 are localized in the endoplasmic reticulum, Golgi apparatus, and endosome. Interestingly, CLEC18 are also detectable in human sera and culture supernatants from primary cells and 293T cells overexpressing CLEC18. Moreover, CLEC18 bind polysaccharide in Ca(2+)-independent manner, and amino acid residues Ser/Arg(339) and Asp/Asn(421) in CTLD domain contribute to their differential binding abilities to polysaccharides isolated from Ganoderma lucidum (GLPS-F3). The Ser(339) (CLEC18A) → Arg(339) (CLEC18A-1) mutation completely abolishes CLEC18A-1 binding to GLPS-F3, and a sugar competition assay shows that CLEC18 preferentially binds to fucoidan, ß-glucans, and galactans. Because proteins with the SCP/TAPS/CAP domain are able to bind sterol and acidic glycolipid, and are involved in sterol transport and ß-amyloid aggregation, it would be interesting to investigate whether CLEC18 modulates host immunity via binding to glycolipids, and are also involved in glycolipid transportation and protein aggregation in the future.