BETHESDA, Md. -- Three months into the first attempt tocorrect a genetic disease with human gene therapy, test resultsindicated that the experiment was working, researchers at theNational Institutes of Health (NIH) reported Monday to theagency's Recombinant DNA Advisory Committee (RAC).
Also going well so far is a week-old experiment that uses genetherapy as a treatment for cancer, researchers said.
In the first experiment, now in its fifth month, gene therapyraised the adenosine deaminase (ADA) levels in a 4-year-oldpatient with inherited ADA deficiency, W. French Anderson ofthe NIH's heart, lung and blood institute told the RAC. The firstthree months of data is the most recent information releasedabout the closely followed experiment. The patient, who lacks afunctioning immune system because of her ADA deficiency, hasbeen given periodic infusions of her own white blood cellsengineered to contain an undamaged ADA gene.
Most important, Anderson said that the girl has not developedleukemia following the gene therapy treatment. This was apossible outcome suggested by the experiment's opponents,who speculated that the inserted gene could disrupt the normalgrowth genes of the patient's white blood cells, causing them toproliferate and result in leukemia. Instead, the child's whiteblood cell count declined when, for technical reasons, sheskipped a treatment.
Two patients being treated for melanoma in the more recentgene therapy experiment involving two patients have notexperienced any side effects of the therapy, said Steven A.Rosenberg of the NIH's cancer institute. The patients, a 29-year-old woman and a 42-year-old man with advancedmelanoma, were treated with cells engineered to contain tumornecrosis factor genes. The patients had not responded toprevious treatment.
An assessment of the treatment's efficacy is several moremonths away, Rosenberg said.
The RAC on Monday approved a gene transfer experiment to beconducted at the St. Jude Children's Research Hospital inMemphis, Tenn. Researchers there plan to use cells engineeredto contain marker genes to investigate the cause of bonemarrow transplant failure. The transplant is used to treat acutemyelogenous leukemia. The experiment must also be approvedby the Food and Drug Administration.
The RAC asked for additional data regarding an experimentproposed by researchers at the University of Pittsburgh. Theyseek to treat skin cancer patients with genetically markedtumor infiltrating lymphocytes (TIL) plus interleukin-2 (IL-2)and interleukin-4.
The NIH's Anderson and Rosenberg were the first to use gene-marked TIL cells with IL-2 to treat skin cancer in 1989.
-- Carol Ezzell Washington Bureau Chief
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