On Friday, shares of biopharmaceutical company Juno Therapeutics Inc. are plunging, down around 31% as of 10:36 AM EST after three patients died in a trial for its leading cancer therapy. The U.S. Food and Drug Administration has put the study on hold.

The study was a Phase II clinical trial of JCAR015, otherwise known as the “ROCKET” trial, in adult patients with relapsed or refractory B cell acute lymphoblastic leukemia (r/r ALL), a cancer that affects the immune system. Two patients died last week after fludarabine, a chemotherapy drug, was added to the treatment. Another patient, who received the same fludarabine additive, died at the end of May.

In response, Juno has suggested to the FDA that the ROCKET trial should continue, using only the cyclophosphamide pre-conditioning with JCAR015. The FDA, however, wants Juno to submit a revised patient informed consent form, a revised investigator brochure, a revised trial protocol, and a presentation copy made to the agency yesterday.

Juno is expected to submit these revised documents this week.

The news has not been kind to other biopharmaceutical companies.

Kite Pharma Inc. , a clinical-stage biopharmaceutical company that focuses on development of cancer immunotherapy products, saw its stock fall over 8% in morning trading, and Bluebird Bio Inc. (BLUE Quick QuoteBLUE - Free Report) , a biotech company that develops therapies for severe genetic disorders, dropped 2% in morning trading, but has recovered slightly.

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