Bispecific antibodies increase the therapeutic window of CD40 agonists through selective dendritic cell targeting

Therapeutic use of agonistic anti-CD40 antibodies is a potentially powerful approach for activating the immune response to eradicate tumors. However, the translation of this approach to clinical practice has been significantly restricted due to the severe dose-limiting toxicities observed in multiple clinical trials. Here, we demonstrate that conventional type-1 dendritic cells are essential for triggering antitumor immunity but not toxicity by CD40 agonists, while macrophages, platelets, and monocytes lead to the toxic events. Therefore, we designed bispecific antibodies that target CD40 activation preferentially to dendritic cells. These bispecific reagents demonstrate a superior safety profile compared to their parental CD40 monospecific antibody, while triggering potent anti-tumor activity. We suggest such cell-selective bispecific agonistic antibodies as a drug platform to bypass the dose-limiting toxicities of anti-CD40, and of additional types of agonistic antibodies used for cancer immunotherapy. Overall design: 2 MARS seq experiments were done: 1) MC38 tumor bearing mice were treated with either mono specific CD40 (5 mice), bi specific CD40/CD11c (7 mice) and PBS (6 mice), and harvested 7 days post treatment for single-cell RNA seq analysis. 2) Mice were treated with mono specific CD40 (2 mice) and bi specific CD40/CD11c 92 mice). 3 hours post treatment LN and spleen were harvested and pooled together from each 2 mice for single-cell RNA seq analysis.