ImmunoGen, Inc. develops pharmaceuticals, primarily for the treatment of cancer. The company's product candidates are called tumor-activated prodrugs and are based on its proprietary immunoconjugate technology platform. Unlike conventional chemotherapeutic agents, tumor-activated prodrugs are intended to deliver potent chemotherapy specifically to a tumor. Each tumor-activated drug immunoconjugate comprises a small-molecule drug which has been chemically linked to a monoclonal antibody.