A patient died in a trial for a new cancer treatment and shares of the company behind it are collapsing

Juno Therapeutics, a Seattle-based biopharmaceutical company, is tanking after another hold has been placed on their trial of a cancer fighting drug.

The company has been developing a treatment called JCAR015 that uses genetically engineered cells to go after a form of adult leukemia.

According to a release from the company, the phase two trial was put on hold after two patients suffered cerebral edema - a dangerous build up of fluid in the brain - this week. One patient has died and another is not expected to recover according to the release

The treatment was previously placed on hold in July after the death of two patients, but was eventually resumed.

"Juno has notified the Food & Drug Administration of the voluntary hold and is working with the agency and the Data and Safety Monitoring Board to determine next steps," Juno said in the press release. "The company is assessing data from the cases and the trial and is evaluating its options regarding the JCAR015 program."

The stock was halted in pre-market trading early Wednesday, and fell over 45% when trade resumed. Since that point, shares have recovered and the stock is down around 30% to $20.50 a share as of 8:40 a.m. ET.