[Review of cancer gene therapy]

Since the first introduction of gene-marking technology to the clinical field in 1989 by Rosenberg et al, more than 4,000 patients have participated gene therapy clinical trials worldwide. Most of those patients had malignancies. Nearly 90% of clinical trials, however, are still in phase I-II stage, and only 3 protocols are in the phase III stage in early 2000. As current clinical gene therapy protocols are intended essentially to examine the safety and feasibility of the new strategy, more careful and steady steps may be required before these clinical trials really produce clinical benefits. Focused on cancer gene therapy, direct and indirect approaches are undertaken. In the direct approach, HSV-TK, HLA-B7, or p53 tumor suppressor gene therapies are the three major approaches historically. In for the indirect approach, cytokine or adhesion molecule gene-transferred tumor cells or immunocompetent cells are considered to be promising to enhance patients' antitumor immunity. In particular, we have concentrated on developing immuno gene therapy using GM-CSF-transduced autologous tumor cells. We have already recruited three patients with stage IV renal cell cancer. In all patients, peripheral blood T cells were mobilized after vaccination with GM-CSF-transduced tumor cells, and two of the three patients showed the persistence of cytotoxic T cells against autologous tumor cells. Clinically, one patient has been followed up with stable disease for more than one year since the start of vaccination. Further clinical studies are required to obtain conclusive results.