Inhibrx, Inc. announced the administration of the first dose of INBRX-106 in a Phase 1 dose-escalation clinical study. INBRX-106 is a novel, hexavalent agonist of OX40 in development for the treatment of solid tumors. The ongoing clinical study aims to determine the safety of INBRX-106 as a single agent and in combination with Keytruda, as well as the recommended therapeutic dose level for future clinical development. INBRX-106 was engineered to bind and cluster six OX40 receptors and has been shown preclinically to significantly outperform bivalent OX40 agonist antibodies in co-stimulatory capacity and anti-tumor activity. INBRX-106 has demonstrated strong single agent activity in preclinical tumor models that do not respond to a PD-1/PD-L1 checkpoint inhibitor. This activity was improved in combination with a PD-1 blocking antibody.