Manufacture of Autologous CD34+ Selected Grafts in the NIAID-Sponsored HALT-MS and SCOT Multicenter Clinical Trials for Autoimmune Diseases

Abstract

To ensure comparable grafts for autologous hematopoietic cell transplantation (HCT) in the National Institute of Allergy and Infectious Diseases-sponsored Investigational New Drug protocols for multiple sclerosis (HALT-MS) and systemic sclerosis (SCOT), a Drug Master File approach to control manufacture was implemented, including a common Master Production Batch Record and site-specific standard operating procedures with "Critical Elements." We assessed comparability of flow cytometry and controlled rate cryopreservation among sites and stability of cryopreserved grafts using hematopoietic progenitor cells (HPCs) from healthy donors. Hematopoietic Progenitor Cells, Apheresis-CD34+ Enriched, for Autologous Use (Auto-CD34⁺HPC) graft specifications included ≥70% viable CD34⁺ cells before cryopreservation. For the 2 protocols, 110 apheresis collections were performed; 121 lots of Auto-CD34⁺HPC were cryopreserved, and 107 of these (88.4%) met release criteria. Grafts were infused at a median of 25 days (range, 17 to 68) post-apheresis for HALT-MS (n = 24), and 25 days (range, 14 to 78) for SCOT (n = 33). Subjects received precryopreservation doses of a median 5.1 × 10⁶ viable CD34⁺ cells/kg (range, 3.9 to 12.8) for HALT-MS and 5.6 × 10⁶ viable CD34⁺ cells/kg (range, 2.6 to 10.2) for SCOT. Recovery of granulocytes occurred at a median of 11 days (range, 9 to 15) post-HCT for HALT-MS and 10 days (range, 8 to 12) for SCOT, independent of CD34⁺ cell dose. Subjects received their last platelet transfusion at a median of 9 days (range, 6 to 16) for HALT-MS and 8 days (range, 6 to 23) for SCOT; higher CD34⁺/kg doses were associated with faster platelet recovery. Stability testing of cryopreserved healthy donor CD34⁺ HPCs over 6 months of vapor phase liquid nitrogen storage demonstrated consistent 69% to 73% recovery of viable CD34⁺ cells. Manufacturing of Auto-CD34⁺HPC for the HALT-MS and SCOT protocols was comparable across all sites and supportive for timely recovery of granulocytes and platelets.

Keywords: Autologous hematopoietic cell transplantation; CD34 selection; Clinical trial; Drug master file; Graft processing; Multiple sclerosis; Systemic sclerosis (scleroderma).