Last month, researchers from the St. Jude Children’s Research Hospital in Memphis, TN, and the University College London (UCL) reported the results from a hemophilia B gene therapy trial that focused primarily on safety. The lead investigators of the study were Amit Nathwani, MD, PhD, UCL Department of Hematology, and National Health Service Blood and Transplant, United Kingdom, and Andrew Davidoff, MD, chair of the St. Jude Department of Surgery. The study data were presented at the 52nd Annual Meeting of the American Society of Hematology (ASH) in Orlando, FL, on December 6, 2010.
Investigators reported no evidence of toxicity in the four patients with severe hemophilia B patients enrolled in the phase I/II trial, all of whom were recruited by the UCL/Royal Free Hospital. St. Jude’s and UCL used low and intermediate doses of the therapy, which has been in development for more than 10 years.
The gene therapy technique for the trial employs adeno-associated viruses (AAV). AAVs, small viruses that do not cause disease and produce mild immune responses, were used as vectors (delivery vehicles) to introduce a functioning factor IX (FIX) gene into the liver cells of subjects with hemophilia B. The goal of the trial is to trigger viable, long-term FIX protein production through a single administration of the therapy. This could reduce or even eliminate bleeding episodes in hemophilia B patients.
The early results suggest that the experimental vector does not trigger the development of inhibitors, as in a previous hemophilia B gene therapy trial. The next step will be to increase the dosage yet again. The third and highest dose of the novel gene-vector combination is scheduled to be infused into the fifth and sixth study participants by mid-January 2011. Investigators will then decide whether to expand the trial to include four more adults with severe hemophilia B. The study will proceed cautiously, using small numbers of subjects, until researchers are sure the treatment is safe.
“Early Clinical Trial Results Following Administration of a Low Dose of a Novel Self-Complementary Adeno-Associated Viral Vector Encoding Human Factor IX in Two Subjects with Severe Hemophilia B” was presented at the ASH meeting as Oral and Poster Abstract #248.
Source: PR Newswire, December 6, 2010