April 10, 2014 | Celladon today became the first company to receive breakthrough status for a gene therapy treatment in development. The treatment, MYDICAR, is intended to reduce the risk of heart failure in patients with a deficiency of the enzyme SERCA2a.
The FDA made its decision to grant breakthrough status to MYDICAR on the basis of Celladon's Phase 1 trial of 39 systolic dysfunction patients. The study reported that subjects receiving high doses of MYDICAR experienced fewer heart failure events than subjects given a placebo, by a factor of more than 80%, and that this reduction was sustained for three years after treatment. No safety issues were reported in this initial trial. Breakthrough status, which is reserved for treatments targeting life-threatening diseases that show significant improvements over the standard of care, allows closer communication with the FDA and potentially an accelerated approval process.
The FDA has never approved a gene therapy product, although the European Commission has approved one such treatment, UniQure's Glybera, for sale in Europe. Regulators have traditionally been wary of the technology after a number of dramatic clinical trial fatalities in the late '90s and early 2000s. However, safety has continually improved in recent years and the freeze on gene therapy may be nearing its end, as a number of companies like Amgen and Bluebird Bio have brought treatments into late-stage clinical trials. MYDICAR, like most gene therapies now in active development, uses a modified adeno-associated virus as a delivery vehicle, inserting a healthy copy of the SERCA2a gene into patients' cardiac muscle cells.