Cheng, Cheng, Liu, and Shen et al. generated a humanized anti-4-1BB IgG4, HuB6, that bound with high affinity to a primate 4-1BB epitope distinct from those bound by clinically unsuccessful 4-1BB agonists, utomilumab and urelumab. HuB6 induced FcγRIA-dependent human CD8+ T, CD4+ T, and NK cell co-stimulation in vitro; dose-dependent tumor growth inhibition in humanized mouse models of syngeneic CRC, alone or combined with anti-PD-L1; and immune memory shown upon tumor rechallenge – all favorable relative to 4-1BB control agonists. Repeat dose safety studies showed HuB6 was well tolerated in humanized 4-1BB mice and cynomolgus monkeys.
Contributed by Paula Hochman
Background: Colorectal cancer (CRC) is one of the most common malignancies and the patient survival rate remains unacceptably low. The anti-programmed cell death-1 (PD-1)/programmed cell death ligand 1 (PD-L1) antibody-based immune checkpoint inhibitors have been added to CRC treatment regimens, however, only a fraction of patients benefits. As an important co-stimulatory molecule, 4-1BB/CD137 is mainly expressed on the surface of immune cells including T and natural killer (NK) cells. Several agonistic molecules targeting 4-1BB have been clinically unsuccessful due to systemic toxicity or weak antitumor effects. We generated a humanized anti-4-1BB IgG4 antibody, HuB6, directed against a unique epitope and hypothesized that it would promote antitumor immunity with high safety.
Methods: The antigen binding specificity, affinity and activity of HuB6 were determined by enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), biolayer interferometry (BLI) and flow cytometry. The antitumor effects were evaluated in humanized mice bearing syngeneic tumors, and possible toxicity was evaluated in humanized mice and cynomolgus monkeys.
Results: HuB6 showed high specificity and affinity for a binding epitope distinct from those of other known 4-1BB agonists, including utomilumab and urelumab, and induced CD8 + T, CD4 + T and NK cell stimulation dependent on Fcγ receptor (FcγR) crosslinking. HuB6 inhibited CRC tumor growth in a dose-dependent manner, and the antitumor effect was similar with urelumab and utomilumab in humanized mouse models of syngeneic CRC. Furthermore, HuB6 combined with an anti-PD-L1 antibody significantly inhibited CRC growth in vivo. Additionally, HuB6 induced antitumor immune memory in tumor model mice rechallenged with 4 × 106 tumor cells. Toxicology data for humanized 4-1BB mice and cynomolgus monkeys showed that HuB6 could be tolerated up to a 180 mg/kg dose without systemic toxicity.
Conclusions: This study demonstrated that HuB6 should be a suitable candidate for further clinical development and a potential agent for CRC immunotherapy.
Author Info: (1) Department of Geriatrics, The First Affiliated Hospital of University of Science and Technology of China, Gerontology Institute of Anhui Province, Division of Life Sciences and
Author Info: (1) Department of Geriatrics, The First Affiliated Hospital of University of Science and Technology of China, Gerontology Institute of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, Anhui, China. Hefei HankeMab Biotechnology Limited, Hefei, 230088, Anhui, China. Anhui Provincial Key Laboratory of Tumor Immunotherapy and Nutrition Therapy, Hefei, 230001, Anhui, China. (2) Department of Genetics, School of Life Science, Anhui Medical University, Hefei, 230032, Anhui, China. (3) Hefei HankeMab Biotechnology Limited, Hefei, 230088, Anhui, China. (4) Anhui Provincial Key Laboratory of Tumor Immunotherapy and Nutrition Therapy, Hefei, 230001, Anhui, China. Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, 230032, Anhui, China. (5) Hefei HankeMab Biotechnology Limited, Hefei, 230088, Anhui, China. (6) Department of Geriatrics, The First Affiliated Hospital of University of Science and Technology of China, Gerontology Institute of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, Anhui, China. Anhui Provincial Key Laboratory of Tumor Immunotherapy and Nutrition Therapy, Hefei, 230001, Anhui, China. (7) Department of Geriatrics, The First Affiliated Hospital of University of Science and Technology of China, Gerontology Institute of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, Anhui, China. Anhui Provincial Key Laboratory of Tumor Immunotherapy and Nutrition Therapy, Hefei, 230001, Anhui, China. (8) Department of Geriatrics, The First Affiliated Hospital of University of Science and Technology of China, Gerontology Institute of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, Anhui, China. Anhui Provincial Key Laboratory of Tumor Immunotherapy and Nutrition Therapy, Hefei, 230001, Anhui, China. (9) Department of Thyroid and Breast Surgery, The First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, Anhui, China. xiaopengma@fsyy.ustc.edu.cn. (10) Hefei HankeMab Biotechnology Limited, Hefei, 230088, Anhui, China. (11) Hefei HankeMab Biotechnology Limited, Hefei, 230088, Anhui, China. (12) Hefei HankeMab Biotechnology Limited, Hefei, 230088, Anhui, China. (13) School of Health Service Management, Anhui Medical University, Hefei, 230032, Anhui, China. zhangymail@ahmu.edu.cn. (14) Department of Geriatrics, The First Affiliated Hospital of University of Science and Technology of China, Gerontology Institute of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, Anhui, China. gdshen@ustc.edu.cn. Anhui Provincial Key Laboratory of Tumor Immunotherapy and Nutrition Therapy, Hefei, 230001, Anhui, China. gdshen@ustc.edu.cn.
