[Inter-laboratory comparison of international standardized BCR::ABL1 (P210) mRNA of chronic myeloid leukemia patients...

Objective: To evaluate the capability of digital PCR (dPCR) in detecting the internationally standardized BCR::ABL1 (P210) mRNA (BCR::ABL1(IS)) of patients with chronic myeloid leukemia through inter-laboratory sample distribution and comparison. Methods: This was a multi-center compatative trial study. A total of 37 samples with different BCR::ABL1(IS) levels were uniformly prepared from patient bone marrow or peripheral blood to be discarded for comparison. Among them, 22 samples were used for real-time reverse transcription quantitative PCR (RQ-PCR) detection to revalidate the conversion factor (CF), whereas another 15 samples, along with 6 samples used in RQ-PCR, were used for dPCR comparison. Peking University People's Hospital determined the validity of its own dPCR and RQ-PCR CFs by detecting World Health Organization international standards. Bland-Altman analysis was conducted to validate the CFs of participating laboratories. If no validated CF was available, the new CF was calculated using the current comparison samples, and its validity was assessed. Results: Among the 14 laboratories participating in the dPCR comparison, 13 detected BCR::ABL1 in all samples. Among the 13 laboratories participating in the RQ-PCR comparison, 5 had validated CFs, whereas the other 8 had validated CFs after recalculating. In the dPCR comparison, 11 laboratories used the same commercial kit, and 10 of them were qualified. Further, 1 laboratory used a laboratory-developed testing reagent and obtained a CF using the standard sample from the National Clinical Laboratory Center, which was also qualified, whereas the 2 laboratories with no CFs both had qualified CFs after calculating. Comparison of results from samples simultaneously performing dPCR and RQ-PCR demonstrated that the BCR::ABL1(IS) results derived from their respective qualified CFs showed no significant difference for each laboratory (all P≥0.1). However, among the 6 laboratories with unqualified original CFs in RQ-PCR, 2 showed significant differences between dPCR results and RQ-PCR results derived from the original CFs (P<0.05), and 3 demonstrated tendencies toward significant differences (P>0.05 to <0.1) . Conclusion: dPCR detection of BCR::ABL1(IS) shows high sensitivity and accuracy and has high consistency with RQ-PCR results.