OBJECTIVECompare the correlation and the concordance of simultaneous bone marrow cytogenetic and peripheral blood molecular responses in patients with chronic myeloid leukemia (CML) during tyrosine kinase inhibitor (TKI) treatment.

METHODSA total of 1 030 pairs of simultaneous bone marrow and peripheral blood samples from 419 patients with CML during TKI treatment were analyzed with standard G-banding techniques and real-time quantitative reverse transcriptase PCR (Q-PCR).

RESULTSThe Spearman correlation coefficient for the paired analysis of the percentage of Ph- positive metaphases versus Q-PCR (BCR-ABL/ABL) values was 0.655 (n=1 030, P<0.01). There was a significant difference in terms of BCR-ABL values among all three cytogenetic response groups of no partial cytogenetic (no PCyR), partial cytogenetic (PCyR) and complete cytogenetic responses(CCyR) (P<0.01). 93.8% of the patients in CCyR had BCR-ABL≤1% [International Scale (IS)], and 97.5% of those with BCR-ABL≤0.1% (IS) were in CCyR. There was good concordance of 86.2% (888 of 1 030 samples) when BCR-ABL values according to cutoffs of BCR-ABL>10%(IS), ≤10%->1%(IS)and ≤1%(IS) were coupled with cytogenetic responses including no PCyR, PCyR and CCyR. Furthermore, 497 pairs of samples from 279 patients with newly diagnosed CML in chronic phase during the first year on TKI as first-line therapy were analyzed. Concordances between major cytogenetic response and BCR-ABL≤10%(IS) at 3 months, CCyR and BCR-ABL≤1%(IS) at 6 months and 12 months were 89%, 83.5% and 92.1%, respectively.

CONCLUSIONThere were significant correlation and concordance between cytogenetic and molecular responses, and some differences in assessment of early responses between using cytogenetic and molecular analyses in CML patients during TKI treatment.