Abstract: A therapeutic composition comprising a chemical conjugatge including a first moiety, other than an immunoglobulin or fragment thereof, such as epidermal growth factor, which preferentially binds to a tumor cell, and is internalized by the cell, and a second moiety linked to the first moiety, and comprising a biodegradable polymeric carrier, such as polyglutamic acid, to which one or more cytotoxic molecules, for instance, daunomycin, are attached. The degradation of the carrier by intracellular enzymes releases a cytotoxic agent, resulting in selective destruction of the tumor cells.