New concepts about graft-versus-host and graft-versus-leukaemia-reactions. A summary of the 5th International Symposium held in Munich, 21 and 22 March 2002

Low-dose cyclosporin A with short-term methotrexate for graft-versus-host disease prophylaxis in allogeneic bone marrow transplantation from human leukocyte antigen-identical siblings: a prospective phase II study in Japanese patients

We hypothesized that reducing the dosage of prophylaxis for graft-versus-host disease (GVHD) would reduce the risk of relapse and toxicity after bone marrow transplantation (BMT) from human leukocyte antigen (HLA)-identical siblings. In a prospective phase II trial, 21 patients with leukemia and myelodysplastic syndrome underwent BMT from HLA-identical siblings and received GVHD prophylaxis consisting of low-dose (1.5 mg/kg per day) cyclosporin A (CSP) with short-term methotrexate (MTX) treatment. This low-dose group was compared with a group of retrospective control patients (n = 22) who received a standard CSP dosage (3.0 mg/kg per day) and MTX. One patient died of transplantation-related causes within 100 days. The regimen-related toxicity was quite tolerable. Although acute GVHD of grades II to III was more frequent in the low-dose group (47.6%) than in the control group (22.7%), the increase in acute GVHD did not significantly contribute to morbidity or mortality. There were no differences between the groups in the incidence and severity of chronic GVHD. The probabilities of relapse and survival of the groups were similar according to the risk for relapse at the time of transplantation. A prospective randomized study is required to determine whether low-dose or standard-dose CSP in combination with MTX is optimal for Japanese patients who undergo allogeneic BMT from HLA-identical siblings.

Characterization of CD20-transduced T lymphocytes as an alternative suicide gene therapy approach for the treatment of graft-versus-host disease

We have previously proposed the CD20 molecule as a novel suicide gene for T lymphocytes in the context of allogeneic bone marrow transplantation, because CD20 can be used both as a selection marker and as a killer gene after exposure to the anti-CD20 therapeutic antibody rituximab. We now report on preclinical studies using this novel system, in which the best transduction protocol, reproducibility, yield, feasibility, and functionality of the transduced T lymphocytes have been investigated with a large donor series. Wild-type human CD20 cDNA was transduced into human T lymphocytes, using a Moloney-derived retroviral vector. Alternative protocols were tested by employing either one or four spinoculations (in which cells are centrifuged in the presence of retroviral vector supernatant) and stimulating T cells with phytohemagglutinin (PHA) or anti-CD3/CD28. One spinoculation alone was sufficient to obtain approximately 30% CD20-positive cells within four experimental days. Four spinoculations significantly increased transduction to 60%. A small difference in transduction efficiency was observed between the two stimulation methods, with PHA being superior to anti-CD3/CD28. Transduced cells could be purified on immunoaffinity columns, with purity reaching 98% and yield being on average 50%. Finally, 86-97% of immunoselected T lymphocytes could be killed in vitro with rituximab and complement. More importantly, the CD20 transgene did not alter the functionality of T lymphocytes with respect to allogeneic recognition and cytotoxic response, anti-Epstein-Barr virus cytotoxic response, antigenic response to tetanus toxoid antigen, interleukin 2 (IL-2), IL-4, and interferon gamma production; chemotaxis in the presence of stromal cell-derived factor 1, phenotype for several activation markers including HLA-DR, CD25, CD69, and CD95, and T cell repertoire.