Preclinical development of complex processing systems for ex vivo culture-expanded lymphohematopoietic cells, with subsequent immunologic and/or genetic manipulation, have been carried out in collaboration with a number of NIH institute investigators, as follows: Preparation of allogeneic donor lymphocytes selectively depleted for alloreactive T-cells using an anti-CD25 immunotoxin (collaboration with NHLBI, Stem Cell Transplant Program): In FY2001, we completed development and scale up of this complex process, and in September 2001, initiated a phase I clinical trial of DLI selectively depleted of donor-specific alloreactivity in the setting of allogeneic hematopoietic transplantation. In FY2002, 3 patients were entered on the clinical trial and received their transplants plus SD cells. This year, we also made plans to evaluate 2 cell manipulation strategies as alternatives to the immunotoxin: one, an immunomagnetic separation method and the other, UV light-activated killing of cells after incubation with a photosensitizing agent. Preparation of donor Th2 T cells for clinical trials (collaboration with NCI): Development of this process incorporated CD8/CD20 depletion and CD3/CD28 bead stimulation, which produces a lymphocyte product that is 95% CD4+ and < 1% CD8+. The clinical trial was initiated in March 2001, and 27 patients have been treated to date through FY2002. Fibronectin transduction: A method for improved gene transduction using fibronectin-coated bags was previously developed and incorporated into the clinical trial of gene therapy for chronic granulomatous disease; that study was completed in 2001. At the end of FY2001, this method was adapted to a new clinical trial of gene therapy in ADA deficiency that takes advantage of new vectors. To date, very high transduction efficiencies (>80%) have been observed, and 2 patients have been treated. In FY2002, methods were improved (with new cytokines) and validated for gene transduction of autologous PBSC and bone marrow of patients with X-linked SCID, and this clinical trial will begin pending resolution of scientific and FDA investigation of the child with apparent vector-induced oncogenesis.
