Two years ago, Jesse Gelsinger, 18, died in a gene therapy trial at the University of Pennsylvania.
Another gene therapy trial treated an immune deficiency but caused cancer in some patients.
In 1999 American teenager Jesse Gelsinger died after having taken part in a gene therapy trial.
A separate convalescent plasma therapy trial that started in Liberia before moving to Sierra Leone did not attract the numbers required for the trial and was abandoned.
The gene therapy trial, halted when the risk was first noticed, has been allowed to resume, even though the possibility of risk has not yet been dispelled.
The study, known as the Hormone Replacement Therapy trial of the Women's Health Initiative, is the first large-scale controlled clinical trial asking whether the therapy prevents heart disease in healthy post-menopausal women.
The promising result of their research comes in the wake of gene therapy's long record of failures and the recent death of a patient, Jesse Gelsinger, 18, in a gene therapy trial at the University of Pennsylvania.
Kgalalelo weighed 48 kilos, had a CD4 count of 220 and a viral load approaching 14,000 before she joined an ARV therapy trial managed by the Harvard-Botswana partnership in August 2001.
The disconcerting finding on heart disease arose in a study, known as the Hormone Replacement Therapy Trial of the Women's Health Initiative, that involves about 25,000 healthy postmenopausal women.
That is the highest level ever seen in a gene therapy trial, high enough to virtually eliminate the need for routine infusions of clotting factor, doctors reported yesterday to the American Society of Hematology in Philadelphia.
While he waited for a tumor sample from Mr. Bucksbaum's neck for B-RAF screening, Dr. Flaherty secured him a spot on an immune therapy trial.
