Abstract
Lack of tumor-reactive cytotoxic T lymphocytes (CTLs) limits the antitumor efficacy of immune checkpoint inhibitors (ICIs). CD40 agonists have been expected to overcome this limitation by generating tumor-reactive CTLs. However, the clinical efficacy of CD40 agonistic antibodies is not as good as in non-clinical studies. The novel human CD40 (hCD40) agonist KHK2840 is a fully human anti-CD40 IgG2 agonistic antibody that is Fc-engineered to minimize complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity. Compared to other hCD40 agonists, KHK2840 exhibited the most potent hCD40 agonistic signal in tumor-bearing hCD40 transgenic mice and human peripheral blood B cells. Moreover, KHK2840 enhanced the antitumor efficacy of the antiprogrammed cell death 1 antibody and paclitaxel. Comprehensive immune profiling revealed that the antitumor immune response of the triple combination involved tumor-draining lymph nodes in addition to tumor microenvironments. This suggests that a coordinated antitumor immune response between tumors and lymph nodes may underlie the synergistic antitumor efficacy of the triple combination therapy. Finally, a toxicology study in cynomolgus monkeys demonstrated that KHK2840 activated the CD40 signal with tolerable toxicological properties. These results indicate that KHK2840 is a novel and potent hCD40 agonistic antibody for cancer immunotherapy, which is expected to augment the antitumor efficacy of ICIs and chemotherapy.