By Deena Beasley

(Reuters) - For 33-year-old video editor and hemophilia patient Travis Roop, being able to get life-saving infusions of a blood clotting agent every two weeks, instead of rushing to treat a bleeding episode, meant he could jog for the first time.

Roop was enrolled in a clinical trial testing a long-acting treatment for hemophilia B from Denmark's Novo Nordisk. The therapy is one of several new blood clotting agents in development that will help hemophilia patients cut by half, or more, the number of regular intravenous infusions they need to prevent traumatic bleeding in their daily lives.

"It was amazing actually. It was a life-changing experience," said Roop, who lives in the Los Angeles area. "I always avoided trauma to my left ankle ... With this, I knew it would take care of itself."

People with hemophilia have a fault in a gene that regulates the body's production of proteins called clotting factors. This can cause spontaneous bleeding as well as severe bleeding following injuries or surgery.

To avoid joint damage and other complications, patients with severe forms of the disease need regular infusions, lasting 30 minutes or more, of relatively short acting and very expensive clotting factors. The number of infusions and their volume depends on the medical status of each patient and their body weight.

Since the gene is carried on the X chromosome, hemophilia is almost entirely a disease of men. But women can pass the gene to their offspring. Hemophilia has often been called the "Royal Disease" since it was carried by Britain's Queen Victoria and affected many of the ruling families of Europe.

The U.S. Food and Drug Administration is due to decide by mid-year whether to approve Alprolix, a new long-lasting hemophilia B clotting factor from Biogen Idec and partner Swedish Orphan Biovitrum. Novo Nordisk expects to file next year for regulatory approval of its long-acting hemophilia B drug, N9-GP.

Some industry experts say these and other new treatments could help drive down the price of existing hemophilia products, which can total $300,000 or more a year for a single patient.

That's because Biogen does not yet market any hemophilia therapies. In the United States, Novo Nordisk sells a drug used only by patients who have developed antibodies to currently-used factors.

If new entrants to the hemophilia market decide to price their longer-lasting factors in line with the overall price of the existing shorter-acting products, the decision for patients to try out the new factors will be relatively easy, said Dr Guy Young, director of the Hemostasis and Thrombosis Center at Children's Hospital Los Angeles.

"If they come in at a similar annual price, then companies that are making recombinant drugs will be forced to drop their price," said Dr Young, who has been involved in clinical trials of long-acting factors.

$11 BILLION MARKET BY 2016

Worldwide, about one in 5,000 men is born with hemophilia A and one in 25,000 men is born with hemophilia B each year.

The global market for hemophilia drugs, led by hemophilia A products such as Baxter International's Advate and Pfizer's Xyntha, totaled $8.5 billion in 2011 and will grow to $11.4 billion by 2016, according to Morningstar.

Deutsche Bank estimates that Biogen's hemophilia products can reach annual sales of $1.2 billion by 2017.

Biogen Chief Executive Officer George Scangos said at an industry conference in January that if insurance companies and other payors view the long-lasting products as simply more convenient, they will be priced in line with existing therapies. If they are viewed as more beneficial, prices will be higher, he said.

Blood factor concentrates were not developed until the mid-20th century, and up until that time people with hemophilia had a life expectancy of less than 30 years. The last major advance in treatment of the rare disease came in the early 1990s when bioengineered clotting factors replaced factors derived from blood plasma.

Factors are numbered using Roman numerals. Hemophilia A is caused by a lack of clotting factor VIII, while hemophilia B is caused by a lack of clotting factor IX.

The new longer-lasting hemophilia B products can be given every 10 days or two weeks, offering significant advantages for patients, especially young children, who now need infusions every two or three days, said Dr Marion Koerper, medical director of the National Hemophilia Foundation and professor of hematology at the University of California at San Francisco Children's Hospital. Koerper has not been involved in clinical trials of longer-acting factors.

"Patients don't always get the doses they are supposed to get," she said, noting that mornings can be hectic and parents may wait to infuse a child at night even though factor levels should be highest when they are running around or at school.

STRONG DEMAND SEEN FOR LONG-ACTING FACTOR IX

Biogen's Alprolix extends the duration of the factor three-fold, while Novo Nordisk's version offers a five-fold increase, Dr Young said. That raises the stakes for Biogen to be first to market its product.

"There is no question that when these drugs get on the market there will be pretty massive and quick uptake," Young said. "I predict most (hemophilia B) patients will end up on one of these new drugs."

Roop, the video editor, said he will seek out Biogen's therapy if it is the first to become available, but has heard that Novo Nordisk's, which he has already tried, works better.

For hemophilia A, the advantages of the new products are less dramatic and uptake will be slower, Dr Young said.

An FDA decision on Biogen's longer-acting hemophilia A therapy, Eloctate, is expected mid-year.

Baxter expects to file by the end of this year for U.S. approval of its long-lasting hemophilia A treatment. Bayer, and CSL Behring also have long-lasting factors in advanced stages of development. Pfizer Inc's work in the field is still in the "discovery" stage.

Meanwhile, biotechnology companies like Sangamo BioSciences and BioMarin Pharmaceutical are working on methods to replace defective hemophilia genes, allowing patients to begin producing their own clotting factor.

Biogen's Scangos acknowledged that new progress is being made in gene therapy, particularly for hemophilia B, but believes that a safe, effective treatment based on this method is still at least five years away.

Roop, who has severe hemophilia B, said he was offered the option of participating in a gene therapy trial, but decided not to take a chance on "unproven science."

"If I can get some longer-lasting factor, maybe get down to just once a month or once every three weeks - I would be happy with that," he said.

Jackson Corral did not benefit during trials of the longer-lasting treatments. The five-year-old Los Angeles area resident, who has hemophilia A, took part in a clinical trial of Biogen's Eloctate.

His mother, Jackie Corral, cannot wait for something to work. She prepares and infuses Jackson and his 3-year-old brother Jameson with a factor VIII product every other morning and always stays within a 20 minute radius of both boys.

"If we did go to twice-a-week infusions that would be amazing," she said. "That would give me so much more peace."