In the latest installment of the saga to halt and then resume many US and European gene transfer and therapy clinical trials, members of the Biological Response Modifiers Advisory Committee (BRMAC) late in February recommended several measures to officials of the Food and Drug Administration (FDA; Rockville, MD) for easing restrictions on trials involving retroviral vectors. Agency officials likely will soon permit many of those recently halted trials to resume, albeit with stronger safety measures than before.
The most cautious advice from BRMAC applies specifically to a handful of trials involving patients with X-linked, severe combined immunodeficiency syndrome (X-SCID). Committee members say that these trials should not resume—unless alternative treatments to save lives are no longer feasible—until new information becomes available from monitoring several additional children who are enrolled in a gene therapy clinical trial at Hôpital Necker-Enfants Malades (Paris, France). Two of the nine children with X-SCID whose immune systems responded positively to the experimental gene therapy during this trial developed leukemia last year, prompting French officials to halt addition of patients to the trial and leading both US and European officials to do the same for trials involving patients with a broader set of diseases but whose therapy also involves introducing retroviral vectors into hematopoietic cells (Nat. Biotechnol. 20, 1068, 2002).
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