Prognostic value of monitoring a candidate immunophenotypic leukaemic stem/progenitor cell population in patients allografted for acute myeloid leukaemia

It is postulated that disease relapse in patients with acute myeloid leukemia (AML) is consequent upon chemoresistance within leukemic stem/progenitor cell (LSC) populations from which bulk blasts arise1. In adults with high risk AML, allogeneic hematopoietic cell transplantation (HCT) has become a central component of the treatment algorithm to overcome this chemoresistance as it delivers maximal anti-leukemic activity through both dose intensification and by the genesis of a potent graft-versus-leukemia (GVL) effect2-4. However relapse still occurs in a significant proportion of allografted patients and now represents the major cause of treatment failure particularly with reduced intensity conditioning (RIC) regimens5. Whilst minimal residual disease (MRD) from the bulk leukemic population is known to be prognostic, more accurate predictors of relapse risk might be developed from detection of putative LSC populations pre- or post-transplant. However, to date an association between LSC and transplant outcome remains uncertain.