THERAPEUTIC FUTURE: Company seeks cure for pulmonary arterial hypertension

Mar. 03, 2013 @ 06:45 PM

In a new lab building constructed on the site of the iconic Elion-Hitchings Building in the Research Triangle Park, United Therapeutics scientists want to search for a cure to hypertension.

In an annual report filed Tuesday with the U.S. Securities and Exchange Commission, the company described its plans for a research facility to work on engineered lungs and lung tissues that could be transplanted into patients with pulmonary arterial hypertension or other lung diseases.

“The reason we're interested in this project is our company's mission is to develop better therapies and, if possible, cure pulmonary arterial hypertension,” said Martine Rothblatt, chairman and CEO of the Maryland-based company.

United Therapeutics currently offers three commercialized treatments for the condition. Last year, the company reported $916 million in revenues. It expects those revenues to climb to about $1 billion this year.

In 2011, the company acquired Revivicor in Virginia, which focused on genetically engineered pigs to provide, among other things, diabetes treatment and organs and tissues for use in transplant surgery known as “xenografts.” The company has also licenses several regenerative medicine technologies, according to the annual report.

For xenografts to succeed, Revivicor's website indicates, the first line of the body's immune response to transplantation from another species must be stopped. So researchers want to neutralize the gene in pigs that creates an enzyme that would trigger am immune response in people.

Few natural lungs are available for transplant, Rothblatt said. Demand is high for transplantable lungs for patients with pulmonary arterial hypertension and other pulmonary diseases.

Daniel Kreisel, an associate professor of surgery, pathology and immunology at Washington University at St. Louis, said that there are many more patients on the waiting list for lung donors than there are donors available.

“For solid organs, there's no programs for it now that would use animal organs, but, obviously, that's been an avenue of research for a long time in an effort to expand the donor pool,” said Kriesel, a surgeon ad a member of the American Society of Transplant Surgeons. He also runs a lung transplantation research laboratory.

Lung transplants from other species to human have never been done before, Rothblatt said, although cells and tissues have been transplanted. Pig heart valves are now used routinely, as well.

Work is expected to start on the new RTP research facility in 2015, with clinical testing possibly kicking off in 2017, Rothblatt said.

She said the company also is working on a project that involves growing a human lung using stem cells taken from a patient's blood and using the template of a pig lung.

Both projects fall under the category of regenerative medicine.

“I'm fairly confident that one of our attempts at regenerative medicine will succeed, but I have no idea which particular one will succeed,” Rothblatt said. “That's why I'm doing several.”

Kriesel didn't seem sold on the idea of lung transplantation from donors as a “cure,” however. The five-year survival rate for patients falls between 50 and 60 percent, he said, because the body rejects the donated organ over time.

“It's not a great cure, per se,” he said, “but it means these patients would otherwise face certain death.”

However, he acknowledged that if transplantation of lungs from animals became possible, it would be an exciting development.

“But how close that is, I can't comment on, because I'm not in that specific research arena,” Kriesel said.