Peripheral blood late mixed chimerism in leucocyte subpopulations following allogeneic stem cell transplantation for childhood malignancies: does it matter?
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Media type:
E-Article
Title:
Peripheral blood late mixed chimerism in leucocyte subpopulations following allogeneic stem cell transplantation for childhood malignancies: does it matter?
Description:
<jats:title>Summary</jats:title><jats:p>The impact of persistent mixed chimerism (<jats:styled-content style="fixed-case">MC</jats:styled-content>) after haematopoietic stem cell transplantation (<jats:styled-content style="fixed-case">HSCT</jats:styled-content>) remains unclarified. We investigated the incidence of <jats:styled-content style="fixed-case">MC</jats:styled-content> in peripheral blood beyond day +50 after <jats:styled-content style="fixed-case">HSCT</jats:styled-content> and its impact on rejection, chronic graft‐versus‐host disease (c‐GvHD) and relapse in 161 children receiving allogeneic <jats:styled-content style="fixed-case">HSCT</jats:styled-content> for haematological malignancies. The 1‐year incidence of late <jats:styled-content style="fixed-case">MC</jats:styled-content> was 26%. Spontaneous conversion to complete donor chimerism (<jats:styled-content style="fixed-case">CC</jats:styled-content>) occurred in 43% of patients as compared to 62% after donor lymphocyte infusions. No graft rejection occurred. The 1‐year incidence of c‐GvHD was 20 ± 7% for <jats:styled-content style="fixed-case">MC</jats:styled-content>, and 18 ± 4% for <jats:styled-content style="fixed-case">CC</jats:styled-content> patients (<jats:italic>P</jats:italic> = 0·734). The 3‐year cumulative incidence of relapse (<jats:styled-content style="fixed-case">CIR</jats:styled-content>) according to chimerism status at days +50 and +100 was 22 ± 4% for <jats:styled-content style="fixed-case">CC</jats:styled-content> patients vs. 22 ± 8% for <jats:styled-content style="fixed-case">MC</jats:styled-content> patients (day +50; <jats:italic>P</jats:italic> = 0·935) and 21 ± 4% vs. 20 ± 7% (day +100; <jats:italic>P</jats:italic> = 0·907). Three‐year <jats:styled-content style="fixed-case">CIR</jats:styled-content>s in patients with persistent <jats:styled-content style="fixed-case">MC</jats:styled-content> and patients with CC/limited <jats:styled-content style="fixed-case">MC</jats:styled-content> were comparable (8 ± 7% vs. 19 ± 4%; <jats:italic>P</jats:italic> = 0·960). <jats:styled-content style="fixed-case">HSCT</jats:styled-content> for acute leukaemia or myelodysplastic syndrome as secondary malignancies (hazard ratio (<jats:styled-content style="fixed-case">HR</jats:styled-content>) 4·7; <jats:italic>P</jats:italic> = 0·008), for <jats:styled-content style="fixed-case">AML</jats:styled-content> (<jats:styled-content style="fixed-case">HR</jats:styled-content> 3·0; <jats:italic>P</jats:italic> = 0·02) and from mismatched donors (<jats:styled-content style="fixed-case">HR</jats:styled-content> 3·1; <jats:italic>P</jats:italic> = 0·03) were independent factors associated with relapse. Our data suggest that late <jats:styled-content style="fixed-case">MC</jats:styled-content> neither protects from c‐Gv<jats:styled-content style="fixed-case">HD</jats:styled-content> nor does it reliably predict impending disease relapse.</jats:p>