Phase I Study of APX005M in Pediatric Central Nervous System Tumors

This is a multicenter phase I trial of APX005M in patients with recurrent or refractory primary malignant central nervous system tumor, or newly diagnosed diffuse intrinsic pontine glioma. APX005M is a humanized IgG1κ mAb that binds to CD40. APX005M binds to both human and cynomolgus monkey CD40 with high affinity, triggering activation of B cells, monocytes, and dendritic cells and stimulating cytokine release from both human and monkey lymphocytes and monocytes. APX005M does not bind to mouse or rat CD40. CD40 is also expressed on many human tumor cells, and APX005M can mediate a direct cytotoxic effect on CD40+ tumor cells. Activation of CD40 on tumor cells results in tumor cell apoptosis and inhibition of tumor growth. CD40 agonistic antibodies have demonstrated potent antitumor immune response stimulation in both animal models and cancer patients. Due to its action on both immune and tumor cells, CD40 has been studied as a target for novel cancer immunotherapy. Apexigen has declared the adult recommended phase 2 dose to be 0.3 mg/kg because no dose limiting toxicities were encountered at that dose and the pharmacodynamic profile was similar to the 1 mg/kg maximally tolerated dose. This phase 1 clinical trial is to study APX005M in children with central nervous system tumors.