Allogeneic transplantation of selected peripheral CD34+ cells with controlled CD3+ cells add-back in high-risk patients.

We evaluated the feasibility of allogeneic transplantation of CliniMACS-selected peripheral CD34+ cells from siblings (four patients: AML-M4, M2, CLL, MDS); nonoptimal related donors (two patients: AML-M4, CML); and unrelated donors (two patients: CML, ALL, both without engraftment after preceding URDBMT). All patients had high-risk of aGVHD and/or graft failure due to multiple transplantation risk factors. Conditioning treatment was myeloablative (n=7) or nonmyeloablative (n=1). Immunosuppression consisted of CsA (n=8), Mtx (n=5), ATG (n=4). Selected CD34+ cells were transplanted (average 3.91 x 10(6)/kg, range 1.29 to 7.27 x 10(6)/kg) together with 0.01 to 0.5 x 10(7) CD3+ cells/kg to assure proper engraftment. The remaining CD34-negative fraction was cryopreserved for further CD3+ cell add-back. Average recovery and purity of CD34+ cells following CliniMACS selection were 74% and 97%. No severe complications were observed in the first 100 days. Regeneration times were satisfactory in seven of eight patients (87.5%) with ANO > 0.5 g/L and Plt > 50 g/L reached on average on days +26 and +32 (range 15 to 29 and 15 to 67), respectively. In three patients (37.5%) T-lymphocytes were added-back one to three times (due to low numbers of initially transfused CD3+ cells in two patients, in one patient with PRCA caused by ABO incompatibility). One to four additional transplantations of nonselected peripheral cells were performed on days +28 to +270 in consequence of infections (CMV-two patients; parvovirus-one patient), poor regeneration and residual disease (one patient) and prolonged transfusion dependency (one patient). Severe aGVHD grade III or IV developed in three patients (37.5%) following the nonselected cells transplantation. Finally, five patients (62.5%) are alive and in remission (median follow-up 815 days). We conclude that allogeneic transplantation of selected peripheral CD34+ cells (CliniMACS) with controlled add-back of CD3+ cells is an effective, well, tolerated procedure in high-risk patients.