An IgG1 chimeric monoclonal antibody agonist of the cell surface receptor CD40 with potential immunostimulatory and antineoplastic activities. Upon intravenous administration, anti-CD40 monoclonal antibody Chi Lob 7/4 binds to CD40 on a variety of immune cell types, triggering the cellular proliferation and activation of antigen-presenting cells (APCs), activating B cells and T cells, and enhancing the immune response; in addition, this agent binds to the CD40 antigen present on the surfaces of some solid tumor cells, resulting in complement-dependent cytotoxicity (CDC) and antibody-dependent cytotoxicity (ADCC) eventually resulting in decreased tumor growth. CD40, a member of the tumor necrosis factor (TNF) receptor superfamily, is expressed on various immune cells, many B-cell malignancies, and many solid tumors, mediating both indirect tumor cell death through the activation of the immune system and direct tumor cell apoptosis.