In vivo efficacy of the CD40 agonist antibody CP-870,893 against a broad range of tumor types: Impact of tumor CD40 expression, dendritic cells, and chemotherapy

2514 Background: CP-870,893 is a fully human IgG2 CD40 agonist antibody currently in early clinical trials. In vitro studies demonstrate its ability to bind human CD40 and enhance dendritic cell costimulatory molecule expression and cytokine production. Methods: In order to assess its potential for cancer therapy, we evaluated the anti-tumor efficacy of CP-870,893 against several CD40pos and CD40neg human tumors in SCIDbeige mice. We specifically addressed the role of tumor CD40 expression, the impact of re-population with human dendritic and T cells on efficacy, and it’s potential to act in synergy with chemotherapeutic agents. Results: We demonstrate that a single i.p. injection of CP-870,893 (T1/2 ∼ 7 days) prevented the growth of several subcutaneous CD40pos tumors including two B cell lymphomas, the breast carcinoma BT-474, and the prostate tumor PC-3 (ED50 = 0.02 mg/kg; Ceff ∼100 ng/mL). Efficacy was demonstrated when CP-870,893 was administered at the time of tumor challenge, but was also observed ...