Clinical Impact Of Post-Transplant Chimerism Monitoring In CD33/34 Bone Marrow Subpopulations and Whole Blood In Pediatric AML: Prospective Comparison Of Highly Sensitive Real Time Sequence Polymorphism PCR Versus Gold-Standard Conventional STR-PCR

CD33/34 lineage specific chimerism analysis (CD33/34 LCA) can improve the predictive value of chimerism monitoring after allo-SCT in AML. Recently, real time PCR (qPCR) has been proposed for highly sensitive and accurate quantitation of chimerism. However, data to compare clinical impact of qPCR versus gold standard conventional STR-PCR was not available. In 2011, we reported on the impact of STR chimerism monitoring in a pediatric AML multicenter study (Rettinger, Willasch et al., Blood 2011;118(20):5681-88). Hereby, we present a prospective analysis on CD33/34 LCA in bone marrow (BM) and mononuclear cell (MNC) chimerism in peripheral blood (PB) by qPCR in the pediatric AML cohort mentioned above. Pre-existing STR-PCR data were used for comparison. This analysis for the first time refers to the clinical impact of a combination of CD33/34 LCA and qPCR technology. Monitoring of 75 transplantations, performed in 72 patients at 11 German pediatric transplant centers between 05/2005 and 04/2009, included 26 (0-84) PB and 5 (0-21) BM samples per patient and covered 1.5 (0.1-4.3) years (median). PB was analyzed weekly and BM at days 30, 60, 100 and 6, 9, 12, 15 and 18 months post-transplant. Lowering the quantifiable limit by qPCR (here CD33/34 subpopulations increased the sensitivity of chimerism monitoring. Early and sensitive detection of impending relapse was possible by qPCR. However, the substantial proportion of false positives had to be kept in mind. Disclosures: No relevant conflicts of interest to declare. [1]: /embed/inline-graphic-1.gif [2]: /embed/inline-graphic-2.gif [3]: /embed/inline-graphic-3.gif