Table 6:

Response and relapse definitions after alloHSCT - Application of monitoring methodologies

Disease	Definition of Complete Remission	Definition of Relapse	Molecular Marker	Cytogenetics	Chimerism	Imaging	Flow Cytometry
AML/MDS	IWG	IWG	Molecular mutations	Chromosome banding analysis, FISH	PCR or VNTR/STR		4–8 color flow
Applicable	All patients	All patients	Subgroups	Subgroups	All patients	Not applicable	All patients
Comment	Well established.	Well established, but less sensitive.	Expansion of MRD marker panel for post-transplant monitoring in AML (e.g., NPM1 mutations) or MDS (e.g., RUNX1/AML1 mutations).*	No standardization for MRD monitoring, useful for specific aberrations.*	Well-established, lack of specificity: investigation of CD34+ specific chimerism*; and standardization of techniques.		Few studies.*
ALL	Less than 5% blasts in BM	More than 5% blasts in BM	TCR- and Ig- Gene rearrangement	Chromosome banding analysis, FISH	PCR or VNTR/STR		4–6 color flow
Applicable	All patients	All patients	90% of all patients	Subgroups	All patients	Not applicable	> 95% of patients
Comment			ASO primer: 80–90% of patients. Ig VDJ: Most patients. BCR-ABL1: All Ph+ ALL.	Clinical not important for MRD assessment.	Gold standard: Singleplex PCR with fluorescent labelled STR primers. Importantly: product resolution using capillary electrophoresis.		Sensitivity in B- lineage ALL is limited after SCT because of large numbers of hematogones.

ALL: acute lymphoblastic leukemia; AML: acute myeloid leukemia; Flow: multiparameter flow cytometry; MDS: myelodysplastic syndromes; qPCR: quantitative real-time PCR; STR: short tandem repeats; VNTR: variable number tandem repeat;

^*Further studies needed.