Molecular monitoring is clearly an important and sensitive tool for evaluating responses as well as for predicting progression-free survival or relapse during targeted therapy for Ph+ CML. Although peripheral blood sampling is relatively easy to perform, obtaining reliable molecular monitoring data can be a challenge for clinicians not associated with institutions routinely performing these assays.
Lack of access to or unreliable molecular response data can compromise therapy for patients with Ph+ CML. Reliable and timely molecular monitoring during therapy has the potential to guide clinical decision making toward optimizing targeted therapy for Ph+ CML.
In a 2008 article that appeared in the journal Blood, Branford et al articulated the need for developing an international standard for comparing Bcr-Abl mRNA levels for the common interpretation of data provided by individual laboratories.1 The authors performed an alignment of Bcr-Abl values from which they were able to calculate the conversion factors used to make standardized interpretation possible.1 The results demonstrate that consistent interpretation of individual patient responses and response rates between clinical trials is possible (see Figures 1 and 2 below).1
Figure 1: Response differences before conversion
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Figure 2: Response differences after conversion
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Recognizing the importance of standardizing RQ-PCR testing, a network of standardized laboratories is currently emerging (see Table 1 below).2 Including local centers, there are 58 standardized labs, 26 of which are equipped to act as national reference centers for their respective countries.
With continued expansion, standardization should reach more than 200 labs across Europe in the near future. Exchange programs are well under way to educate laboratory personnel on standardized RQ-PCR testing, which will help to rapidly implement the standards in all participating European countries.
Table 1:
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Next: Guidelines and Recommendations for Monitoring CML
Note: Before prescribing, please read full European Summary of Product Characteristics.
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References
- Branford S, Fletcher L, Cross NCP, et al. Desirable performance characteristics for BCR-ABL measurement on an international reporting scale to allow consistent interpretation of individual patient response and comparison of response rates between clinical trials. Blood. 2008;112(8):3330-3338.
- Müller MC, Cross NCP, Erben P, et al. Harmonization of molecular monitoring of CML therapy in Europe. Leukemia. 2009;23:1957-1963.
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