Gene therapy: Chemoprotection, immunoenhancement, and modification of tumor cells

Concepts for studies designed to introduce safety-modified retroviruses into repopulating cells of the bone marrow are reviewed here. These studies will set the stage for chemotherapy protection programs that involve insertion of drug resistance genes into the early progenitor cells of the hematopoitic system. We also describe studies under way to modify tumor cells, so as to provoke a more dramatic and decisive cytotoxic response from the effector cells of the immune system. These are new directions in therapy that may enhance and complement standard programs of therapy and lead to the control of neoplastic disease currently uncontrolled by existing modalities.