Abstract
Abstract Introduction: Immune checkpoint blocking antibodies achieved great clinical success, yet a large fraction of cancer patients receive minimum benefit from current immunotherapies targeted PD-1 and CTLA-4. As a new multifunctional immune checkpoint molecule, TIGIT holds promise to become an important cancer immune therapy target. AK127 is a novel humanized immunoglobulin (Ig) G1 monoclonal antibody (mAb) targeting T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT). AK127 binds to TIGIT specifically and blocks the interaction of TIGIT with its ligands, thus relieves immune suppression and promotes anti-tumor immune response. Method: The effect of AK127 on secretion of IL-2 in mixed culture of Jurkat-TIGIT and HT1080-aCD3scFv cells (ELISA) was determined in cellular assays. Binding kinetics of AK127 to C1q, FcγR were measured by Fortebio. ADCC, ADCP and CDC activities were determined in cellular assays. In preclinical in-vivo pharmacology studies, synergistic anti-tumor activity of AK127 and a bi-specific anti-PD1/CTLA4 antibody Cadonilimab (AK104) was investigated in BALB/c-hPD-1/hTIGIT transgenic mice with CT26.WT tumor model. Result: AK127 blocked the immune inhibitory signal mediated by TIGIT, resulting in enhanced IL-2 secretion. AK127 exhibited binding to FcγIa, FcγRIIIa and C1q, and eliciting ADCC, ADCP and CDC. In animal models, both AK104 (0.5 mg/kg) and AK127 (4 mg/kg) significantly inhibited tumor growth. The combination of AK127 and AK104 produced a significantly enhanced anti-tumor effect than either monotherapy, demonstrating the synergistic anti-tumor activity of AK127 combined with AK104. Conclusion: AK127 binds to human TIGIT with high affinity, competitively blocks the binding of TIGIT with its ligand CD155 and CD112, relieves immune suppression in both cellular and animal model systems, and promotes anti-tumor immune response. Citation Format: Zhaoliang Huang, Xinghua Pang, Tingting Zhong, Chunshan Jin, Na Chen, Dennis Xia, Peng Zhang, Max Wang, Michelle Xia, Baiyong Li. AK127, a novel monoclonal antibody (mAb) targeting T cell immunoreceptor (TIGIT) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5524.
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