Treatment plan
Re-induction CloEC chemotherapy consisted of clofarabine 40
mg/m2/day, etoposide 100 mg/m2/day,
and cyclophosphamide 340 mg/m2/day, and it was given
on five consecutive days. Children responding to the first course of
CloEC received the second course and proceeded to transplantation.
Children not responding to the first course were given the second
course, and if that did result in fulfillment of the transplant
criteria, an additional (third) course of CloEC was administered pending
transplantation. Children not responding to the second course entered
the palliative care program. Those with > 5% blasts on day
21 after the beginning of the first course were immediately started on
the second course. Those with ≤ 5% blasts in hypoplastic bone marrow
(BM) were re-evaluated once a week until regeneration occurred or the
blasts increased, and then proceeded to the second course. The minimum
interval between CloEC courses was 21 days.
The conditioning regimen consisted of clofarabine 200
mg/m2 or fludarabine 150 mg/m2,
thiotepa 10 mg/kg, and melphalan 120 mg/m2, and it was
given between days –8 and –1 prior to grafting. Serotherapy with ATG
(Fresenius) at a total dose of 30 mg/kg was administered from day –12
to day –10 before grafting. For patients with ALL, the preferred donor
was always the mother if there was no medical contraindication for
donation. For AML patients, donor selection was based on KIR mismatch:
if mismatch was observed, the mother was the first choice and the father
second choice; if no mismatch was present, the mother was chosen. The
donors were screened, evaluated, and accepted by an independent team of
adult hematologists.
Peripheral blood stem cells were mobilized with G-CSF, and all donors
were harvested twice. The collected cells were processed with the
CliniMACS system for immunomagnetic cell separation (Miltenyi Biotec,
Gladbach, Germany). The first harvest entailed selection of CD34+ cells,
whereas the second harvest was for depletion of T cells expressing the
αβ chains of T cell receptor (TCR). Maximum allowed dose of TCR αβ+
cells was set at 5 x 105 cells/kg. A single dose (375
mg/m2) of anti-CD20 antibody (Rituximab) was
administered on day +1 after grafting instead of performing B-cell
depletion in vivo. Graft-versus-host prophylaxis included the
above-mentioned serotherapy, graft processing, and a short course of MMF
600 mg/m2 tid given from day –1 to day +28 if the
number of residual αβ TCR positive cells in the graft exceeded
2.5x104/kg of donor’s body weight.