The Boston, US-based biotech announced the death in a US SEC filing on July 15, explaining that the patient died 15 days after starting on a 30-mg dose of the gene therapy.
The patient is the third to die during the study. However, unlike the first two deaths which Ziopharma attributed to the “medically fragile” state of the subjects rather the study drug, the root cause has yet to be determined.
“The cause of death is intracranial hemorrhage, which occurred some time after the patient had been discharged from the treating center” the firm said, adding that “we are collecting and analyzing information in order to properly and timely report it to the FDA.”
The study is examining a combination of Ad-RTS-hIL-12 – an adenovirus vector engineered to a make a protein called IL-12 that improves the immune system’s ability to kill tumours – and an oral activator ligand called veledimex that controls expression.
The activator ligand was developed by privately-owned Intrexon Corporation using its RheoSwitch DNA activation platform.
News of the third death saw Ziopharm’s share price fall 17% in trading on the NASDAQ on Friday.
The Ph I study, which is being conducted at Cedars-Sinai Medical centre in California and Northwestern, the University of Chicago and Brigham & Women's in Massachusetts, is still enrolling patients.
Ziopharm did not respond to a request for comment.