Retroviral-mediated gene transfer has permitted the development of cli
nical protocols for the study and treatment of genetic diseases and ca
ncer. These protocols can be divided into proposals either for gene la
belling (transfer) or for gene therapy. Labelling studies include the
tracking of gene-modified cells (e.g., tumor-infiltrating lymphocytes,
bone marrow tumor cells) infused into the patient. Most gene therapy
protocols are designed to deliver a therapeutic protein using a mature
differentiated cell population (e.g., fibroblasts). A number of proto
cols to treat genetic diseases and cancer have been recently initiated
. The approval process for the clinical studies requires a multi-agenc
y review due to the safety and ethical concerns. While safety issues o
f the procedure still exist, gene therapy holds much promise as an eff
ective treatment modality.