ABSTRACT
Gene therapy is a rapidly evolving field in which a wide variety of therapeutic approaches are being considered and tested. Approaches to treatment of various lung diseases include study and use of adenovirus vectors (Rosenfeld et al., 1991, 1992; Engelhardt et al., 1993; Crystal et al., 1994), adeno-associated virus vectors (Flotte et al., 1992, 1993), and DNA/liposome vectors (Canonico et al., 1994; Malone et al., 1989) for delivery of therapeutic genes. Retroviral vectors have also been studied (Drumm et al., 1990). In regulating product development in such an area, it is important to be flexible and attentive to practical limitations. If the barrier to starting exploratory clinical trials is too high, then only a few therapies will be tried and the ones that might have succeeded may be missed. On the other hand, the public should be protected from unnecessary or unreasonable risk, and also from the raising of unrealistic hopes. In its oversight of biological products for gene therapy, the Center for Biologies Evaluation and Research (CBER) of FDA seeks a balance between these considerations. As time goes on and a longer track record accumulates, it will likely be possible to relax recommendations for some 90types of testing which pioneering investigators had to perform. Sponsors should be aware that change in regulatory policy occurs more quickly now than in the past, especially in an area like gene therapy with rapidly evolving technology. However, when products reach later stages of development, standards for approval call for demonstration of efficacy, as with any other product.
