Preclinical Characterization Of A Novel Fully Human Igg1 Anti-Pd-L1 Mab Ck-301

Antibodies targeting Programmed Death-1 (PD-1), or its ligand, PD-L1, have demonstrated remarkable efficacy in subsets of cancer patients, with inhibition of the interaction between PD-1 on T-cells and PD-L1 on tumor cells leading to the recovery of anti-tumor immune response and immune-mediated eradication of tumors. However, not all patients respond to existing PD-1 and PD-L1 targeting agents and relapses to therapy still occur. Therefore, there exists a need to identify additional therapeutics and approaches to engage the immune system to enhance the efficacy of current anticancer therapies. Using phage and yeast display approaches, we have discovered and optimized a novel, fully human, PD-L1 specific IgG1 antibody, CK-301, which exhibits subnanomolar binding affinity for PD-L1. CK-301 blocks binding of PD-L1 to both PD-1 and B7-1 in enzyme-linked immunosorbent assays (ELISA) and cell-based competition assays. Using an assay measuring inhibition of a nuclear factor of activated T-cells (NFAT) reporter caused by PD-L1 binding to PD-1, we demonstrate that CK-301 completely reverses reporter inhibition at concentration of less than 1 µg/ml, IC50 of the dose response curve is 80ng/ml. CK-301 enhances IFN-gamma secretion in allogeneic mixed lymphocyte reaction (MLR) using primary human T-cells and immature dendritic cells. CK-301 can also trigger antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) mediated killing of PD-L1+ cell lines, including lymphoma cells. CK-301 has similar subnanomolar affinity for cynomolgus monkey PD-L1 as for human PD-L1, hence we chose Macaca fascicularis for pre-clinical toxicology and safety pharmacology studies. Single-dose administration of CK-301 to monkeys up to the highest tested dose of 100 mg/kg was shown to be safe and demonstrated linear dose-dependent pharmacokinetic (PK) properties over the dose range from 1 to 100 mg/kg with a half-life of 15 days at 100 mg/kg. A first-in-human Phase 1 study of CK-301 is planned to commence in mid-2017. Citation Format: Leonid Gorelik, George Avgerinos, Yune Kunes, Wayne A. Marasco. Preclinical characterization of a novel fully human IgG1 anti-PD-L1 mAb CK-301 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4606. doi:10.1158/1538-7445.AM2017-4606