Juno Therapeutics voluntarily placed a hold its clinical study of a leukemia candidate after two patients died.

The hold affects the Phase II clinical trial of a CAR-T immunotherapy candidate for adults with relapsed or refractory B cell acute lymphoblastic leukemia. Juno will work with the FDA and a Data and Safety Monitoring Board to further assess data from the trial and evaluate its options.

In July, Juno informed the Securities and Exchange Commission that it experienced four patient deaths in a leukemia trial. As a result of the deaths, the FDA had put a hold on the company’s study, which was lifted less than a week later.