Gelsinger, investigators say, should not have been given the experimental treatment, not only because of dangerously high levels of ammonia in his blood, but also because of the adverse side effects suffered by others in the trial.

"The entry levels for ammonia (readings) were not met," said Kathryn Zoon, an FDA investigator. Gelsinger is considered the first person to die while undergoing gene therapy.

Zoon said the Pennsylvania researchers failed to notify the agency of two other patients who suffered liver damage severe enough to stop the trial. But Rebecca Harmon, a University of Pennsylvania spokeswoman, said the FDA was properly informed as required.

Doctor defends therapy trial

At a meeting reviewing this and other gene therapy trials at the National Institutes of Health, Dr. Jim Wilson, one of the doctors treating Gelsinger, said the patient's ammonia levels were being controlled medically.

VIDEO
CNN's Eileen O'Connor reports
on the FDA gene therapy finding.

Wilson also said the FDA was kept informed. "Our interpretation of the data made available to the FDA eight months prior to Jesse's therapy and death did not suggest to us that the trial should be modified at that point or halted," Wilson said.

Researchers at the university, where the experiment was part of a series of gene therapy trials, are to present their findings when the NIH hearing resumes Thursday.

Gelsinger, of Arizona, was a participant in the clinical trial conducted to study gene therapy for a rare disorder called ornithine transcarbamylase deficiency (OTC), an inherited liver disease that causes life-threatening levels of ammonia to build up in the blood.

Virus carried corrective gene

As part of that trial, his liver was injected with a virus carrying a corrective gene.

The virus used in the trial usually causes flu-like symptoms, but in Gelsinger the symptoms escalated into respiratory distress. He died of multiorgan failure in September.

The FDA approved the trial with certain parameters, including that the trial be stopped if patients had serious side effects.

Harmon said the FDA was informed about the two other patients, as was Gelsinger's father.

Paul Gelsinger said he does not blame the doctors for his son's death, but the FDA, for failing to act on the information of adverse side effects from earlier trials.

The elder Gelsinger said his son's doctors told him about the other two patients but indicated one may have had complications which would have caused the side effects.

The FDA says these are preliminary results, and the investigation is not complete.

Medical Correspondent Eileen O'Connor and The Associated Press contributed to this report.

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