Gene therapy represents an exciting new avenue to find cures for many diseases. Hemophilia A is an ideal choice for this type of treatment because the mutations that influence factor VIII production are limited to a specific gene, the mechanism and genetics are well known, improvement is easily measured, and the potential benefit is large. Previous gene therapy trials have been conducted for hemophilia A, but due to transient low-level factor VIII expression and lack of therapeutic efficacy, none of the trials were continued. At Expression Therapeutics, we plan to overcome this problem by using our bioengineered factor VIII transgene, which has demonstrated the necessary increased production rates in preclinical gene therapy animal studies.