Clinical Edge

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Gene therapy restored immunity in newly diagnosed SCID-X1

Key clinical point: Gene therapy combined with low-dose busulfan appears to successfully treat X-linked severe combined immunodeficiency.

Major finding: Seven infants had normal immune cells 3-4 months after treatment, while the eighth infant responded after a gene therapy boost.

Study details: A dual-center, phase 1/2 study of eight consecutive infants with newly diagnosed X-linked severe combined immunodeficiency.

Disclosures: Study funders included the American Lebanese Syrian Associated Charities, the National Institutes of Health, the California Institute of Regenerative Medicine, and the Assisi Foundation of Memphis. St. Jude Children’s Research Hospital has licensed the gene therapy and partnered with Mustang Bio to develop and commercialize it. Dr. Mamcarz reported receiving grant support from the study funders.


Mamcarz E et al. N Engl J Med. 2019; 380:1525-34.