Objective: Peripheral blood progenitor cells (PBPC) have been established as an alternative source of hematopoietic stem cells for allogeneic transplantation, but an increased incidence of both acute and chronic graft-vs-host disease (GVHD) has become apparent. We performed a prospective randomized trial comparing bone marrow transplantation (BMT) vs PBPC transplantation (PBPCT) using CD34(+) selection for T-cell depletion (TCD) in both study arms.
Patients and methods: Between January 1996 and October 2000, 120 patients with a diagnosis of acute leukemia, myelodysplasia, multiple myeloma, or lymphoma were randomized to receive either filgrastim-mobilized PBPC or BM from HLA-identical sibling donors after standard high-dose chemoradiotherapy. Patient characteristics did not differ between study arms.
Results: Recipients of PBPC received more CD3(+) T cells (median: 3.0 vs 2.0 x 10(5)/kg, p<0.0001) and more CD34(+) cells (median: 3.6 vs 0.9 x 10(6)/kg, p<0.0001). Neutrophil and platelet recoveries occurred significantly faster after PBPCT. The cumulative incidence of acute GVHD grades II-IV was 37% after BMT vs 52% after PBPCT and was most significantly (p=0.007) affected by the number of CD3(+) T cells in the graft. Acute GVHD appeared strongly associated with increased treatment-related mortality (TRM) in a time-dependent analysis. Higher numbers of CD34(+) cells were associated with less TRM. With a median follow-up of 37 months (range: 12-75), overall survival at 4 years from transplantation was 60% after BMT and 34% for recipients of PBPCT (p=0.04), which difference was largely due to increased GVHD and TRM in PBPC recipients receiving T-cell dosages greater than 2 x 10(5)/kg.
Conclusion: Outcome following T cell-depleted PBPCT critically depends on the number of CD3(+) T cells, whereby high T-cell numbers may blunt a favorable effect of higher CD34(+) cell numbers.