Cowen analyst Yaron Werber said Bluebird Bio reported data at the EHA meeting that was "highly encouraging" for Zynteglo and announced EU pricing that was higher than he expected. However, the comapny also unexpectedly said the EMA has requested amendments that will delay the launch of the drug in the EU out to early 2020, according to Werber. Additionally, the manufacturing process changes requested add some new risk, said the analyst. In afternoon trading, Bluebird Bio shares have slid to their worst levels of the session, down $7.06, or 5.7%, to $116.88.