Somatic Gene Therapy

Gene therapies are currently being studied in more than 50 clinical trials. This method holds considerable promise for many inborn errors of metabolism. Gene therapy for inborn errors of metabolism requires the development of biologically sound strategies for correcting metabolic defects, vectors for controlling the expression of therapeutic genes, and methods for delivering vectors safely to patients.

The efficacy of gene therapy will ultimately need to be assessed and demonstrated relative to conventional therapeutics. While it is widely believed that many inborn errors of metabolism may come to be best treated by gene therapy, these will also be significant advances in the development of conventional pharmaceutical products, biological products such as enzyme replacement, and transplantation, including the potential for inducing tolerance to allogeneic or xenogeneic grafts.

The question “Why gene therapy?”

The intense social discourse conserning the propriety and etical implications of gene therapy has been largely resolved with the realization that somatic gene therapy is in principle no different than replacing deficient functions with enzyme replacement therapy or organ transplantation. Because of intense social concern generated by gene therapy, clinical trials in the United States are reviewed in public by the Recombinant Advisory Committee (RAC) of the National Institute of Health as well as by the Food and Drug Administration (FDA) through the traditional IND (Investigational Drug) process. A similar review process has been established by many European countries and the European Union,

The first clinical trials using retroviral vectors demonstrated the feasibility and social and regulatory acceptance of gene transfer into human subject. The initial trials have greatly expanded interest in gene therapy and led to a more focused analysis of the potential clinical indications for gene therapy.

To date, the number of patients treated is still too small to fully assess the safety or efficacy of either retroviral vectors or any specific gene therapy.

Since the commencement of the first clinical trial involving gene transfer into human subjects in 1989, more than 100 patients have been treated and more than 100 patients have been treated and more than 70 clinical trials are underway.

Many of the ongoing clinical trials are gene marking trials, in which genes are introduced into cells prior to transplantation to study their fate and function. The majority of current clinical trials are aimed at gene therapy for cancer.