Efficacy and Safety of the Cryopreserved Formulation of OTL-101 in Subjects With ADA-SCID

This is a prospective, non-randomized, single-cohort, longitudinal, single-center, clinical study designed to assess the efficacy and safety of a cryopreserved formulation of OTL-101 (autologous CD34+ hematopoietic stem/progenitor cells transduced ex vivo with EFS (Elongation Factor 1α Short form) Lentiviral Vector (LV) encoding for the human ADA gene) administered to ADA-SCID subjects between the ages of 30 days and 17 years of age, who are not eligible for an Human Leukocyte Antigen (HLA) matched sibling/family donor and meeting the inclusion/exclusion criteria. The OTL-101 product is infused after a minimal interval of at least 24 hours following the completion of reduced intensity conditioning. For subjects who successfully receive the OTL-101 product, pegademase bovine (PEG-ADA) Enzyme Replacement Therapy (ERT) is discontinued at Day+30 (-3/+15) after the transplant. After their discharge from hospital, the subjects will be seen at regular intervals to review their history, perform examinations and draw blood samples to assess immunity and safety.