Several studies have reported that chronic myeloid leukaemia (CML) patients expressing e14a2 BCR::ABL1 have a faster molecular response to therapy compared to patients expressing e13a2. To explore the reason for this difference we undertook a detailed technical comparison of the commonly used Europe Against Cancer (EAC) BCR::ABL1 reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) assay in European Treatment and Outcome Study (EUTOS) reference laboratories (n = 10). We found the amplification ratio of the e13a2 amplicon was 38% greater than e14a2 (p = 0.015), and the amplification efficiency was 2% greater (P = 0.17). This subtle difference led to measurable transcript-type dependent variation in estimates of residual disease which could be corrected by (i) taking the qPCR amplification efficiency into account, (ii) using alternative RT-qPCR approaches or (iii) droplet digital PCR (ddPCR), a technique which is relatively insensitive to differences in amplification kinetics. In CML patients, higher levels of BCR::ABL1/GUSB were identified at diagnosis for patients expressing e13a2 (n = 67) compared to e14a2 (n = 78) when analysed by RT-qPCR (P = 0.0005) but not ddPCR (P = 0.5). These data indicate that widely used RT-qPCR assays result in subtly different estimates of disease depending on BCR::ABL1 transcript type; these differences are small but may need to be considered for optimal patient management.

几项研究报道，与表达 e13a2 的患者相比，表达 e14a2 BCR::ABL1的慢性髓性白血病 (CML) 患者对治疗的分子反应更快。为了探索这种差异的原因，我们对欧洲治疗和结果研究 (EUTOS) 参考实验室中常用的欧洲抗癌 (EAC) BCR::ABL1逆转录酶定量聚合酶链反应 (RT-qPCR) 测定进行了详细的技术比较( n  = 10)。我们发现 e13a2 扩增子的扩增率比 e14a2 高 38% ( p  = 0.015)，扩增效率高出 2% ( P = 0.17)。这种细微的差异导致残留疾病估计中可测量的转录类型依赖性变异，这可以通过 (i) 考虑 qPCR 扩增效率来纠正，(ii) 使用替代 RT-qPCR 方法或 (iii) 液滴数字 PCR (ddPCR) )，一种对放大动力学差异相对不敏感的技术。在 CML 患者中，与 通过 RT-qPCR（P = 0.0005） 而非ddPCR （P = 0.5)。这些数据表明，根据BCR::ABL1转录物类型，广泛使用的 RT-qPCR 分析导致对疾病的估计略有不同；这些差异很小，但可能需要考虑到最佳患者管理。