Minimal GVHD following in-vitro T cell-depleted allogeneic stem cell transplantation with reduced-intensity conditioning allowing subsequent infusions of donor lymphocytes in patients with hematological malignancies and solid tumors.

OBJECTIVE: Allogeneic stem cell transplantation (alloSCT) following reduced-intensity conditioning offers a relatively nontoxic regimen while preserving rapid and sustained engraftment. Acute and chronic graft-vs-host disease (GVHD) is, however, a significant cause of severe morbidity. To reduce the incidence of GVHD, we treated a group of high-risk patients with a reduced-intensity conditioning regimen followed by in vitro T-cell-depleted alloSCT using Campath 1-H incubation. PATIENTS AND METHODS: Eighteen patients were treated with fludarabine (6 x 30 mg/m(2)), busulphan (2 x 3.2 mg/kg), and ATG (4 x 10 mg/kg) followed by the infusion of high-dose T-cell-depleted peripheral stem cells from sibling donors. No posttransplant GVHD prophylaxis was administered. At 6 months after alloSCT, low-dose donor lymphocyte infusion (DLI) was administered.
RESULTS: All patients had sustained engraftment of donor cells with a median of 95% donor cells at 3 months after alloSCT. Minimal acute and no chronic GVHD was observed after alloSCT. A high incidence of cytomegalovirus (CMV) reactivation but no CMV disease was observed. Eleven patients received DLI at a median of 6.5 months after alloSCT. Acute GVHD grade II-III developed in 6 patients. All patients showed improvement of donor chimerism after DLI. With a median follow-up of 211 days, 11 patients are alive. Particular in patients with chronic lymphocytic leukemia and acute myeloid leukemia, a significant graft-vs-tumor effect was observed.
CONCLUSIONS: In vitro T-cell-depleted alloSCT following reduced-intensity conditioning leads to durable donor engraftment without GVHD. The high levels of donor chimerism allow the subsequent use of cellular immunotherapy to treat residual disease.