Gene Therapy Shows Early Promise for Heart Failure
Those gains, however, were "modest," and need to be viewed with some caution, said Dr. Lee Goldberg, medical director of the Heart Failure and Cardiac Transplant Center at the University of Pennsylvania in Philadelphia.
Goldberg pointed out that early studies like this one are set up primarily to see if a therapy is safe, and to figure out what drug dose to use in larger trials -- not to test effectiveness.
"A major limitation of the study is that there was no placebo group," said Goldberg, who also chairs the American College of Cardiology's Heart Failure and Transplant Council. That means there's no way of knowing whether some study patients were showing a "placebo effect" -- the phenomenon where people feel or even function better simply because they believe they received an effective treatment.
Penn said his team is working on a next-stage trial of 90 patients, which will include a group that receives a placebo.
Another cardiologist agreed that the findings on the therapy's benefits have to be "taken with a grain of salt."
"But I do think this seems feasible, and worth studying further," said Dr. David Friedman, chief of heart failure services at North Shore-LIJ's Plainview Hospital, in Plainview, N.Y.
Researchers have long sought to use stem cells to repair diseased hearts, which has included taking stem cells from heart failure patients' bone marrow and infusing them into the heart.
But this new approach, Friedman said, would avoid the steps of harvesting, culturing and reintroducing stem cells into patients. And, according to Penn, it should also be less costly.
For now, though, Goldberg said, "there are many, many unanswered questions. How durable will these effects be? Are there any unintended side effects in the long term?"
It's also not certain that the gene therapy did, in fact, recruit patients' stem cells to their damaged hearts. The researchers could not measure that directly.
Even with all the uncertainties, Goldberg said it's exciting to see that this approach could be feasible. "I am cautiously optimistic," he said.
One thing everyone agreed on was that the ultimate hope is to develop heart failure therapies that somehow rehabilitate damaged heart muscle. Right now, heart failure treatment involves drugs and lifestyle changes that relieve symptoms and ease the workload on the heart. But the disease does ultimately progress, until patients eventually need implanted devices or, as a last resort, a heart transplant.
Penn is the founder of Juventas Therapeutics Inc., which is developing SDF-1-based therapies for heart failure and other diseases.
Learn more about heart failure from the U.S. National Heart, Lung, and Blood Institute.