Table 1.

Summary of Gene Therapy Outcomes and Current Status for Primary Immune Deficiencies.

Primary Immunodeficiency	Overall Outcomes and Current Status
ADA-SCID	100% survival with most achieving protective immune function No complications due to viral vector with over 70 patients treated thus far. Becoming standard of care for patients without matched sibling donors
X-linked SCID	In initial trials utilizing gammaretroviral vectors, 5 of 20 patients developed acute T cell leukemia due to viral integration near proto- oncogenes. Subsequent trials utilizing self-inactivating gamma-retroviral or lentiviral vectors demonstrate stable engraftment without leukemic events thus far.
Chronic Granulomatous Disease (CGD)	Early trials were not able to achieve sustained gene correction or resulted in insertional oncogenesis Parallel clinical trials in Europe and the US are utilizing lentiviral vectors with a myeloid-specific promoter driving expression of the transgene.
Wiskott Aldrich Syndrome (WAS)	Permanent correction of immunodeficiency was achieved in the majority of patients treated in the initial trial. However, leukemia occurred in 7 of 10 patients due to the retroviral vector. Trials using self-inactivating lentiviral vectors are open in Europe and the US without evidence of genotoxicity thus far.