Hepatocellular carcinoma (HCC) is the predominant form of primary liver cancer. It ranks the third leading cause of cancer-related death globally, with high incidence and mortality in Southeast Asia. Unfortunately, majority of HCC patients are diagnosed at intermediate to advanced stages when treatment options are limited and the chance of tumor recurrence is high. Our previous studies demonstrate that endogenous and circulating annexin A3 (ANXA3) promotes self-renewal, tumor growth, and resistance to standard chemotherapy and targeted therapy in HCC, thus potentially offering a new target for HCC treatment. The use of humanized antibodies is more clinically relevant than non-humanized counterparts because of their reduced risk of triggering immune responses in human patients. In the era of precision medicine, there is a growing emphasis on tailor-made treatment considers personal genetic differences or environmental conditions. With advances in technology enabling the rapid detection of ANXA3 expression in an individual, the potential use of a humanized anti-ANXA3 antibody alone or in combination with other approved therapeutics represents a meaningful step forward to improving therapeutic outcomes of HCC patients with ANXA3 upregulation.

Herein, a humanized anti-ANXA3 monoclonal antibody was developed and extensively characterized for its therapeutic efficacy utilizing both in vitro and in vivo HCC models.

In vitro, our humanized anti-ANXA3 mAb in combination use with standard chemotherapy cisplatin or targeted therapy sorafenib or lenvatinib demonstrated synergistic effects in suppressing cell proliferation, inducing apoptosis, reducing tumor-initiating cell frequency, and re-sensitizing therapy-resistant cells to their respective treatments. In vivo, the combinational treatments similarly showed maximal tumor shrinkage, tumor-initiating frequency reduction, and therapy-resistant tumor re-sensitizing effects. Importantly, the humanized anti-ANXA3 mAb administration did not elicit any toxicity on a humanized peripheral blood lymphocyte (Hu-PBL) mouse model with respect to animal body weight and tissue weight changes and plasma biochemistry panel readouts. Animal behavioural tests also showed no significant difference in animal muscle strength, locomotor ability, and anxiety level.

Findings of this study also explored the potential of expanding the use of the humanized anti-ANXA3 mAb to multiple malignancies with ANXA3 overexpression.