(Reuters) - Global Blood Therapeutics Inc’s sickle cell disease treatment met the main goal of a late-stage trial, but scepticism over whether the drug would get an accelerated review from health regulators pushed its shares down 12 percent.

The U.S. biotech company said it would seek accelerated approval for the drug, voxelotor, on the basis of its effectiveness against hemolytic anemia, a condition where red blood cells are destroyed and removed from the bloodstream.

“Investors are likely digesting the potential risks associated with the company’s aggressive regulatory strategy to gain approval on hemolytic markers,” said William Blair analyst Raju Prasad.

Global Blood also said it would not use a tool it had designed for the trial to measure clinical benefit in the patient’s daily lives as a secondary goal of the study, as this data was difficult to interpret.

“They apparently plan to move ahead with accelerated review without it (the secondary goal),” said Wedbush analyst Liana Moussatos, noting that this could cause volatility in the stock.

The company said it plans to present results from the trial at a medical meeting later this year. Data from a later phase of the study is expected in the first half of 2019.

The data on Wednesday showed that a statistically significant number of patients on the treatment, voxelotor, experienced a rise in levels of hemoglobin - a protein in red blood cells that carries oxygen throughout the body - compared to a placebo.

“There is well-documented correlation of organ loss and premature death with hemoglobin,” company executives said on a call with analysts, noting that the company’s discussions with the Food and Drug Administration revolved around the rise in hemoglobin levels.

Sickle cell disease is a potentially life-threatening disorder that can lead to failure of the organs. The disease affects about 100,000 Americans and in 1 in 13 black or African-American babies are born with the trait, the Centers for Disease Control and Prevention estimates.

The company’s shares, which touched a low of $33.80 in early trading, eased to trade down 5.2 percent at $26.70.