The present disclosure describes anti-B7H3 antibody agents and uses relating thereto. Among other things, the present disclosure demonstrates particular immunomodulatory effectiveness of certain such antibodies. The present disclosure further describes particularly high-affinity or otherwise useful antibodies and antibody agents based thereon, including particularly certain humanized and/or affinity matured versions of an 8H9 antibody. In some embodiments, provided antibody agents are useful, for example, in the treatment of cancer. In some embodiments, provided antibody agents are useful in relieving immunosuppression, for example mediated by B7H3-positive cells.
