Gene therapy for haemophilia.
Progress toward the development of a gene therapy protocol for the treatment of haemophilia has been substantial. Recent achievements include high level clotting factor expression in mice, dogs, and monkeys as well as phenotypic correction in both mouse and canine models of haemophilia. Studies using adenoviral vectors have contributed to much of the recent success. However, the repertoire of gene transfer vehicles being applied to the development of gene therapy strategies for haemophilia has expanded. In particular, encouraging data has been generated from studies using recombinant adeno-associated virus vectors. Progress toward human clinical trials has been inhibited by host immune responses to treatment which can limit the duration of therapy and prevent readministration. Several strategies have demonstrated the feasibility of circumventing host immune responses, but more effective, clinically applicable procedures remain to be developed. While direct in vivo gene therapy strategies have generated significant progress, the results from ex vivo strategies have not been as encouraging.
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Genetic Therapy, Inc., 19 Firstfield Road, Gaithersburg, Maryland 20878, USA.