Are contemporary methods for somatic gene therapy suitable for clinical applications?

Clinical trials involving the introduction of recombinant genes into human subjects began in 1989 after a decade of earnest debate concerning the technical, social, and ethical implications of somatic gene therapy. The initial trials involved the introduction of recombinant genes into peripheral blood lymphocytes to study the characteristics of tumor infiltrating lymphocytes, enhance immunotherapy for cancer, and treat severe combined immunodeficiency due to adenosine deaminase deficiency. Additional clinical trials involving the introduction of genes into bone marrow, hepatocytes, and tumor cells are underway. Are these clinical trials premature? This article reviews basic methods for somatic gene therapy and the clinical trials which have been proposed or performed to date. This clinical experience suggests that gene therapy can be performed in select clinical trials safely and with public acceptance. Clinical trials have provided essential data concerning the feasibility and safety of gene transfer in human subjects. These trials have also brought a clinical focus to the assessment of technologies currently being used in experimental models. While there will certainly be significant advances in somatic gene therapy in the future, existing methods may be employed fairly in clinical trials.