PERSONALISED testing protocol in acute lymphoblastic leukaemia (ALL) has been developed to allow for earlier and more accurate prediction of relapse. These assays can precisely quantify more minimal residual disease (MRD) markers in less sample material, which can lead to improved clinical outcomes by closely observing clonal tumour evolution.
ALL is the most common malignancy in children and, while the 5-year event-free survival rate has increased to 80% over the past decades, cancer recurrence still leads to poor clinical outcomes. The most important prognostic parameter in both adult and paediatric ALL is MRD, which refers to the number of cancer cells that remain in the patient during or after treatment.
Although the current MRD monitoring protocol employs highly sensitive technologies, there is still a risk of false-negative results due to the nature of the MRD markers that are currently in use. Consequently, the authors of the study developed a quantitative, multiplex, patient-specific quantitative real-time PCR assay based on the mediator probe (MP) PCR for monitoring up to four MRD markers. Study Co-investigator Michael Lehnert, Hahn-Schickard, Freiburg, Germany, elucidated the discovery: “Multiplexing can significantly improve personalised MRD monitoring of patients, because a higher number of MRD markers per patient can be analysed at the same time. Even though these patient-specific sequences of cancer cells only differ in a few DNA nucleotides from healthy cells, our multiplex assay can still distinguish between these DNA sequences. Therefore, a broader range of patient-specific sequences can be included in the assay.”
The authors demonstrated the potential of personalised multiplex MP PCRs by demonstrating that in a direct comparison duplex MP PCR was as effective as the gold standard singleplex real-time PCR quantification. Additionally, the authors presented simple MRD-MP guidelines for the design of primers and mediator probes, which are easy to implement and allow standardisation of MRD analysis. Commenting on the relevance of these findings, the study’s Principal Investigator, Cornelia Eckert, Department of Pediatric Oncology/Hematology, Charité – Universitätsmedizin Berlin, Germany; German Cancer Consortium (DKTK), Heidelberg, Germany; and German Cancer Research Center (DKFZ), Heidelberg, Germany, noted: “After successful clinical validation, patients could benefit from extended MRD monitoring, leading to more precise predictions of therapy response and better patient stratification and outcomes.”