Target population
The target population for this prospective study comprised children and adolescents referred to our institution with relapsed/refractory (r/r) AL (ALL or AML including sAML), who were aged > 1 and ≤ 21 years at the time of enrollment. For both ALL and AML, refractoriness was defined as chemoresistant isolated or combined bone marrow relapse, relapse > 6 months after allogeneic HSCT, or primary induction failure. Patients relapsing after allogeneic HSCT could be recruited directly. Patients relapsing after conventional treatment were to have at least one failed remission induction attempt before enrollment. Disease status was mandatory for inclusion and was assessed by both morphological examination and immunophenotyping prior enrollment. The following additional eligibility criteria were necessary for enrollment: cardiac output SF ≥ 25%; adequate renal function indicated by calculated creatinine clearance ≥ 90 ml/min/1.73 m2 (calculated by the Schwartz formula for estimated glomerular filtration rate [GFR]); adequate liver function indicated by serum bilirubin ≤ 1.5 × upper limit of normal (ULN); aspartate transaminase/alanine transaminase; alkaline phosphatase ≤ 2.5× ULN; Lansky or Karnofsky performance status of ≥ 70%; a suitable adult haploidentical family member available for stem cell donation and fulfilling institutional criteria for blood and marrow donation. Informed consent and assent (adjusted to different age categories) from patients/parents were required for enrollment. The study was approved by the Swedish Ethical Review Authority (File no. 2009/83) and registered at clinicval.trials.gov (NCT01025778) and the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT number 2009-012437-30), and it was conducted in accordance with the principles of the Helsinki Declaration.