Gene therapy rises from the dead

Gene therapy--the idea of replacing a patient's defective genes with healthy ones--was hyped in the 1990s as the next big leap forward in drug development. But a series of high-profile setbacks left the entire gene therapy field on death's doorstep. Yet today, 189 companies are developing gene therapies, and 354 U.S. studies are being conducted as developers continue to pursue game-changing treatments for some of the most difficult-to-treat diseases.

Gene therapy was first used to treat a small group of children with severe combined immunodeficiency disorder, also known as "bubble boy" syndrome. In that trial, gene therapy experience the first of what would be many setbacks in the field, when five children in the trial developed leukemia, and another died of a massive immune response. More recently, a woman died in 2007 after participating in a Phase I trial of Targeted Genetics' gene therapy tgAAC94. "Gene therapy was dead as a doornail," Axel Polack, a general partner in TVM Capital, tells Bloomberg. "No one was investing anymore. People were fed up with big promises and not seeing any results."

But now drug developers big and small are investing heavily in the field, which has experience a rebirth as drugmakers refine their approach to replacing imperfect genes with healthy ones. "Gene therapy has matured," says Weill Cornell Medical College researcher Ronald Crystal, as quoted by Bloomberg. "Now the real challenge is to choose the right targets, which diseases and, from a commercial point of view, which markets make sense."

A laundry list of Big Pharma companies are jumping into gene therapy. Genzyme, a leader in the rare disease space, has poured upwards of $200 million in the last decade into developing gene therapies. Novartis recently inked a $213 million deal with GenVec to collaborate on a preclinical program for hearing loss and balance disorders. Pfizer struck a $145 million deal with Tacere Therapeutics, giving the drug giant access to Tacere's preclinical hepatitis C drug. And that's just the tip of the iceberg. Gene therapy is being explored for common diseases like Parkinson's and Alzheimer's, as well as rare genetic diseases. "Despite earlier negative publicity and disappointment, the reality is that science has forged ahead," notes one researcher.

- read the Bloomberg report for more