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production of an enzyme known as SERCA2a that plays a key role in recycling calcium in the heart’s muscle cells. Heart muscle cells need calcium to contract and relax, and a variety of conditions—such as coronary artery disease, diabetes, and alcoholism and drug abuse—can contribute to progressive heart failure. Regardless of the cause, heart failure typically leads to a loss of enzyme function. As a result, the heart cannot pump blood forcefully enough to keep fluid out of the tissues and lungs. Patients’ legs and arms swell, they feel a constant shortness of breath, and occasionally experience acute episodes that feel like drowning—requiring emergency room treatment or hospitalization.
Celladon is developing a treatment that uses a small, benign virus to deliver a fresh supply of SERCA2a enzymes into the muscle cells of the heart. The company says Mydicar is intended for patients who have been diagnosed with advanced chronic heart failure and who are suitable for this particular type of gene therapy. The company estimates that about 350,000 patients with systolic heart failure fit this criteria in the United States.
Current treatment options for such patients are usually expensive and involve a heart transplant or the surgical implantation of a pump known as a left ventricle assist device.
In general, over 6 million people are currently diagnosed with heart failure in the United States. There are more than 1 million heart failure-related hospitalizations and about 280,000 deaths each year.
A treatment that reduces heart failure-related hospitalizations by more than 80 percent could have a dramatic impact on healthcare costs. By one recent estimate, the direct costs of heart failure in the United States is $60 billion a year—with heart failure-related hospitalizations pegged at $37 billion.
“That’s why reducing hospitalizations by 88 percent is such a big deal,” Zsebo said.
The FDA’s breakthrough therapy designation was enacted as part of the FDA Safety and Innovation Act in mid-2012. It means the FDA has determined that an experimental therapy addresses a serious or life-threatening condition, and preliminary clinical data indicates the drug may “demonstrate substantial improvement over existing therapies.”
While FDA regulators have granted the designation to 40 small-molecule compounds over the past two and a half years, only two biologics were designated as breakthrough therapies as of March 31, according to the FDA. Mydicar would be the third, and the first gene therapy to win the designation.
[Updated to show AGTC completed IPO, instead of pending] Although initial forays into gene therapy were stymied in the 1990s, the field has rebounded in recent years. Forbes recently reported that 11 different companies have raised at least $668 million from venture capitalists and the public markets since the beginning of 2013, and one more, Florida-based AGTC, completed a $50 million initial public offering earlier this month.
Once the FDA has designated a drug development program as a breakthrough therapy, the agency says, it will work closely with the company developing the drug to ensure that the clinical trials can be conducted as efficiently as practicable.