The term "detectable signal" is a signal derived from non-invasive imaging techniques such as, but not limited to, positron emission tomography (PET). The term "therapeutically effective amount" refers to at least the minimal dose, but less than a toxic dose, of an agent which is necessary to impart a therapeutic benefit to a subject. The term "epitope" or "antigenic determinant" refers to a site on an antigen (e.g., huCD40) to which an immunoglobulin or antibody specifically binds. For example, a CD40 agonist and one or more additional antibodies (e.g., CTLA-4 and/or PD-1 and/or (...)