Immunoglobulin G (IgG) antibodies have been used to treat cancer for many years (1). Another class of antibodies—immunoglobulin M (IgM)—has been overlooked in spite of offering unique advantages that make them highly desirable as cancer therapeutics. Serving a valuable function in our innate immune system, IgM antibodies are the first to be secreted when an abnormal cell is present (2). These antibodies play a critical role in recognition and elimination of infectious particles (3,4), in removal of intracellular…