Robust and cost effective expansion of human regulatory T cells highly functional in a xenograft model of graft-versus-host disease.

The low frequency of naturally occurring regulatory T cells (nTregs) in peripheral blood and the suboptimal protocols available for their ex vivo expansion limit the development of clinical trials based on the adoptive transfer of these cells. We have, therefore, generated a simplified, robust and cost-effective platform for the large-scale expansion of nTregs using a gas permeable static culture flask (G-Rex) in compliance with Good Manufacturing Practice. More than 10(9) putative Tregs co-expressing CD25 and CD4 molecules (92 ± 5%) and FoxP3 (69 ± 19%) were obtained within 21 days of culture. Expanded Tregs showed potent regulatory activity in vitro (80 ± 13% inhibition of CD8(+) cell division) and in vivo (suppression or delay of graft-versus-host disease in a xenograft mouse model) indicating that the cost-effective and simplified production of nTregs we propose will facilitate the implementation of clinical trials based on their adoptive transfer.

The costs and cost-effectiveness of allogeneic peripheral blood stem cell transplantation versus bone marrow transplantation in pediatric patients with acute leukemia.

In a retrospective study, we evaluated the cost and cost-effectiveness of allogeneic peripheral blood stem cell transplantation (PBSCT) (n = 30) compared with bone marrow transplantation (BMT) (n = 110) in children with acute leukemia after 1 year of follow-up. Treatment success was defined as disease-free survival at 1 year posttransplantation. For patients at standard risk for disease, the treatment success rate was 57.1% for PBSCT recipients and 80.3% for BMT recipients (P = not significant [NS]). The average total cost per treatment success at 1 year in the standard-risk disease group was $512,294 for PBSCT recipients and $352,885 for BMT recipients (P = NS). For patients with high-risk disease, the treatment success rate was 18.8% for PBSCT recipients and 23.5% for BMT recipients (P = NS). The cumulative average cost was $457,078 in BMT recipients and $377,316 in PBSCT recipients (P = NS). Point estimates of the incremental cost-effectiveness ratio (ICER) indicate that in patients with standard-risk disease, allogeneic BMT had lower costs and greater effectiveness than PBSCT (ICER, -$687,108; 95% confidence interval [CI], $2.4 million to dominated). For patients with high-risk disease, BMT was more effective and more costly, and it had an ICER of $1.69 million (95% CI, $29.7 million to dominated) per additional treatment success. The comparative economic evaluation provides support for BMT in standard-risk patients, but much uncertainty precludes a clear advantage of either treatment option in patients with high-risk disease. More studies using larger and randomized controlled trials are needed to confirm the long-term cost-effectiveness of each procedure.

Preparing for growth: current capacity and challenges in hematopoietic stem cell transplantation programs.

During the past decade, the demand for hematopoietic stem cell transplantation has grown dramatically, and there are expectations that this will continue or even accelerate over the next decade. This prompts a variety of questions about the ability of the health care system to accommodate the increased demands on transplantation centers; for example, what is the current patient capacity of transplantation programs, and how much elasticity do they have to accept a larger volume of patients? An informal survey of a sample of medical directors of transplantation programs found that existing facilities might be able to increase their patient volume by about 7%. Expanding much beyond that limit will require an infusion of resources to enlarge current programs and/or establish new programs.

Long-term outcome of EBV-specific T-cell infusions to prevent or treat EBV-related lymphoproliferative disease in transplant recipients.

T-cell immunotherapy that takes advantage of Epstein-Barr virus (EBV)-stimulated immunity has the potential to fill an important niche in targeted therapy for EBV-related cancers. To address questions of long-term efficacy, safety, and practicality, we studied 114 patients who had received infusions of EBV-specific cytotoxic T lymphocytes (CTLs) at 3 different centers to prevent or treat EBV(+) lymphoproliferative disease (LPD) arising after hematopoietic stem cell transplantation. Toxicity was minimal, consisting mainly of localized swelling at sites of responsive disease. None of the 101 patients who received CTL prophylaxis developed EBV(+) LPD, whereas 11 of 13 patients treated with CTLs for biopsy-proven or probable LPD achieved sustained complete remissions. The gene-marking component of this study enabled us to demonstrate the persistence of functional CTLs for up to 9 years. A preliminary analysis indicated that a patient-specific CTL line can be manufactured, tested, and infused for $6095, a cost that compares favorably with other modalities used in the treatment of LPD. We conclude that the CTL lines described here provide safe and effective prophylaxis or treatment for lymphoproliferative disease in transplantation recipients, and the manufacturing methodology is robust and can be transferred readily from one institution to another without loss of reproducibility.