[Abstract]

After the surprising reports at NEJM Jun. 2012 on the phase I studies of anti-PD-L1 and PD-1 antibodies amazed the whole oncology fields, Immediately, ‘Immune checkpoint inhibitory antibodies’ have become one of the most promising drugs to treat several cancers in the clinics, of which 6 antibodies got approvals from US FDA for several solid cancers, so far. Especially, I/O drugs’ reinvigoration of immune reactivity toward cancers have been quite successful and the enhanced usage of these antibodies as a ‘backbone’ regimen of anti-cancer combination treatments are highly expected. Currently, in pursuing more potent combination I/O treatment, unprecedented number of basic, preclinical and clinical studies are in process on the globe. In search for our own I/O drug development, an anti-PD-L1 antibody, ‘KL001’ was successfully developed. The candidate antibody showed strong in vitro, ex vivo immune-modulating activities and in vivo anti-cancer efficacies. Epitope mapping analysis showed its’ uniqueness and mouse toxicity study showed safety of the candidate. Successful affinity maturation resulted in improved druggability of the candidate antibody (KL001-13) and stable cell-line development generated the cell-line with high level antibody production (~4.4 gram/liter). The further development of ‘KL001-13’, anti-PD-L1 antibody will provide good experiences for immune-oncology drug development and highly efficacious anti-cancer antibody drug candidate.