Cell targeting and immunostimulatory properties of a novel Fcγ-receptor-independent agonistic anti-CD40 antibody in rhesus macaques

Biochemical and hematological reference intervals in rhesus and cynomolgus macaques and implications for vaccine and drug development

Nonhuman primates have a key role in the evaluation of novel therapeutics including vaccine and drug development. Monitoring biochemical and hematological parameters of macaques is critical to understand toxicity and safety, but general reference intervals following standardized guidelines remain to be determined. Here we compiled multiple internal datasets to define normal ranges of classical biochemical and hematological parameters in Indian and Chinese rhesus macaques as well as cynomolgus macaques. Furthermore, the combination of hematological data with phenotypic information of cells obtained by flow cytometry enabled analyses of specific immune cell subsets. We found that vaccination generally induced transient changes at 24 h in cell frequencies accompanied by fluctuation in selected liver enzymes and metabolites. However, most parameters remained within our identified reference intervals. These deviations did not lead to noticeable side effects. Fluctuation in selected biochemical and hematological parameters was accompanied with differentiation of CD14+CD16+ intermediate monocytes and upregulation of genes associated with interleukin-1 signaling. By contrast, two animals with noticeable side effects showed sustained deviations. This study provides insights into baseline and vaccine-induced biochemical and hematological profiles of healthy macaques, facilitating the interpretation of toxicity and safety assessments in preclinical trials of novel therapies.

Fcγ-Receptor-Independent Controlled Activation of CD40 Canonical Signaling by Novel Therapeutic Antibodies for Cancer Therapy

The activation of CD40-mediated signaling in antigen-presenting cells is a promising therapeutic strategy to promote immune responses against tumors. Most agonistic anti-CD40 antibodies currently in development require the Fcγ-receptor (FcγR)-mediated crosslinking of CD40 molecules for a meaningful activation of CD40 signaling but have limitations due to dose-limiting toxicities. Here we describe the identification of CD40 antibodies which strongly stimulate antigen-presenting cells in an entirely FcγR-independent manner. These Fc-silenced anti-CD40 antibodies induce an efficient upregulation of costimulatory receptors and cytokine release by dendritic cells. Finally, the most active identified anti-CD40 antibody shows activity in humanized mice. More importantly, there are no signs of obvious toxicities. These studies thus demonstrate the potent activation of antigen-presenting cells with anti-CD40 antibodies lacking FcγR-binding activity and open the possibility for an efficacious and safe combination therapy for cancer patients.