Ablynx says blood disorder drug estimates conservative BRUSSELS (Reuters) - Belgian biotech company Ablynx believes its sales estimate for its drug for the rare blood disease TTP is conservative, after tests showed it had potential to treat more than just acute cases. Ablynx recently raised its estimate for peak annual sales for the TTP candidate drug caplacizumab to 300-400 million euros ($373-497 million), from up to 250 million euros previously. "You might still be being conservative around there," Chief Executive Edwin Moses told Reuters in an interview. There is potential for indication expansion beyond the target group of patients. TTP is a rare disorder in which microscopic clots form in small blood vessels throughout the body. Ablynx says there are about 10,000 episodes per year in the United States and Europe. Moses said trial results published in June had not just shown statistical significance in terms of initial treatment, but also protection from relapses. He said the revised sales target was based on improved pricing assumptions. Health insurers, he said, would be willing to pay a lot for patients spending less time in hospital, but also for fewer relapses, which can lead to neurological or tissue damage. He said Ablynx's latest assumptions did not include the drug's potential as a first-line treatment or preventative tool for the 30-40 percent of cases that relapsed, or occasional use for the 10 percent of cases in which TTP is chronic. Ablynx expects to talk with health regulators in Europe and the United States early next year to see if it can secure approval for the drug before the end of phase III trials, which it plans to start in 2015. Moses said he saw a greater chance of success on that front in Europe, meaning caplacizumab could eventually be launched at the end of 2017, or early 2018. Without such conditional approval, the drug launch would likely be some two years later. Ablynx, a specialist in nanobodies -- antibody-derived proteins targeting disease -- has a large number of experimental drugs, many in partnership with big pharmaceutical companies, but none has yet reached the market. It is also starting a Phase II trial on infants of its own candidate drug to counter RSV, a virus causing acute respiratory infections, particularly during early childhood. It eventually could come to market by about 2021.