A phase II trial that was stopped because of unexpected deaths, and then restarted in July this year, has been suspended again following the death of more patients.

The trial of an experimental chimeric antigen receptor T-Cell (CAR-T) therapy JCAR015 by Juno Therapeutics involved adult patients with relapsed or refractory B cell acute lymphoblastic leukaemia.

The two patients who died had cerebral oedema like the three patients who died when the trial was put on clinical hold the first time.

The FDA allowed the trial to resume after Juno postulated that the three earlier deaths were potentially due to the addition of fludarabine to the treatment, which the company then substituted with cyclophosphamide.

“The clinical course with these two cerebral oedema patients was very similar to what we saw in July,” said Mark Gilbert, the company’s chief medical officer was reported to have said in a conference call with industry analysts.

“We did not expect the removal of fludarabine to eliminate entirely the risk of neurotoxicity or cerebral oedema.”

The company has put the trial on voluntary hold and the FDA has as yet declined to comment.