Use of nonmyeloablative preparative regimens for allogeneic blood stem cell transplantation: induction of graft-vs.-malignancy as treatment for malignant diseases

Antiviral responses following L-leucyl-L-leucine methyl esther (LLME)-treated lymphocyte infusions: graft-versus-infection without graft-versus-host disease

Although allogeneic hematopoietic progenitor cell transplant (HPCT) is curative therapy for many disorders, it is associated with significant morbidity and mortality, which can be related to graft-versus-host disease (GVHD) and the immunosuppressive measures required for its prevention and/or treatment. Whether the immunosuppression is pharmacologic or secondary to graft manipulation, the graft recipient is left at increased risk of the threatening opportunistic infection. Refractory viral diseases in the immunocompromised host have been treated by infusion of virus-specific lymphotyces and by unmanipulated donor lymphocyte infusion (DLI) therapy. L-leucyl-L-leucine methyl ester (LLME) is a compound that induces programmed cell death of natural killer (NK) cells, monocytes, granulocytes, most CD8(+) T cells, and a small fraction of CD4(+) T cells. We have undertaken a study of the use of LLME-treated DLI following T cell-depleted allogeneic HPCT, specifically to aid with immune reconstitution. In this ongoing clinical trial, we have demonstrated the rapid emergence of virus-specific responses following LLME DLI with minimal associated GVHD. This paper examines the pace of immune recovery and the rapid development of antiviral responses in 6 patients who developed viral infections during the time period immediately preceding or coincident with the administration of the LLME DLI.

Mobilization of allogeneic peripheral blood progenitor cells

It is possible to reliably obtain sufficient PBSC from most normal donors to perform allogeneic transplantation. The mobilization regimen, usually administration of a single daily dose of G-CSF at 7.5 to 10 micrograms/kg subcutaneously for 4 to 6 days, is tolerable with acceptable side effects. However, there is wide variability among individuals with respect to the extent of mobilization achieved by the regimen and the optimal timing of apheresis. Studies suggest that the likelihood of obtaining an adequate harvest of CD34+ cells, as defined locally may be enhanced by employing higher doses or different schedules of G-CSF, monitoring the mobilization and/or collection of PBPC, and using apheresis procedures processing 2 or more times blood volume. However, an optimal regimen for mobilization and harvesting for all donors has not yet been identified and a small percentage of donors may not mobilize adequately with G-CSF. Alternative regimens employing combinations of G-CSF and GM-CSF are available that may prove useful in such cases and novel cytokines that are even more effective than G-CSF in mobilizing stem cells are eagerly awaited. Based on currently available experience with normal donors, the short-term safety of G-CSF appears to be acceptable, however there exist several scenarios in which marrow harvesting may be preferable to G-CSF mobilization and apheresis collection of PBPC.

Allogeneic stem cell transplantation for acute lymphocytic leukemia in adults

Acute lymphocytic leukemia remains a difficult disease to treat in adults. Allogeneic bone marrow transplantation can cure some patients with ALL, but GVHD transplant-related mortality and disease relapse remain problematic. Immunotherapeutic approaches aimed at eliminating minimal residual disease and enhancing the GVL effect may decrease relapse rates and improve overall survival. Because of the rarity of this disease in adults, every new patient should be entered in well-designed, peer-reviewed, investigational trial.

Therapy for childhood acute myeloid leukemia: role of allogeneic bone marrow transplantation

Acute myeloid leukemia (AML) has one of the lowest survival rates of childhood cancers. The first significant improvement in AML therapy started with the introduction of the now standard regimen of 3 days of anthracyclines and 7 days of cytarabine (Ara-C), the so-called 3+7 combinations. Several different therapeutic approaches have been taken in attempts to improve the outcome, including intensification of therapy both for remission induction and in the postremission phase. Intensification of postremission therapy included multiple courses of high-dose chemotherapy and/or myeloablative therapy followed by stem- cell rescue from either allogeneic or autologous sources. Furthermore, risk-tailored therapy is now possible, by cytogenetic risk stratification, promptness of remission induction, and identification of distinct clinical subgroups such as children with Down syndrome. This approach is rapidly changing potential therapeutic strategies for children with AML. It is in this changing mileu that we address the proper role of stem-cell transplantation, a modality that is changing (like chemotherapy) with expanding stem-cell sources and approaches to decrease transplant-related toxicity.