Medical Information

While the survival rate for children with acute lymphoblastic leukemia (ALL)—the most common cancer in children—is more than 80%, survival among children whose cancer recurs is less favorable. A new monitoring protocol could detect disease recurrence sooner, according to a study published in The Journal of Molecular Diagnostics.

Personalized mediator probe polymerase chain reaction (MP PCR) for minimal residual disease (MRD) monitoring of ALL could be the new standard in personalized MRD monitoring, according to the authors.

Since MRD markers can disappear during treatment, false-negative results can occur and lead to wrong decision-making in personalized treatments, but the MP PCR “can precisely quantify more MRD markers in less sample material,” the authors explained. “Therefore, clinical outcomes will be less affected by clonal tumor evolution,” which causes MRD markers to disappear.

The personalized MP PCR is an iterative workflow and guidelines to design multiplex real-time PCRs to monitor up to 4 MRD markers for ALL simultaneously in 1 assay. The researchers tested the personalized MP PCR in bone marrow samples from patients with ALL and found it met the EuroMRD gold standard guidelines and level of sensitivity for clinical decision-making.

“Multiplexing can significantly improve personalized MRD monitoring of patients, because a higher number of MRD markers per patient can be analyzed at the same time,” co-investigator Michael Lehnert, PhD, of Hahn-Schickard Freiburg, said in a statement. “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 researchers designed 4 personalized MP PCRs for 3 MRD markers: Ig/TCR gene rearrangements, gene fusions, and gene deletions. The new assay was applied in a patient case, and 2 samples taken during treatment were assessed for MRD. They found the personalized MP PCR fulfilled the EuroMRD guidelines.

It was also compared with the gold standard in MRD monitoring: singleplex hydrolysis probe PCR. “It can be concluded that here the multiplex MP PCR approach is at least as good as the gold standard,” the authors wrote. “Both fulfill the EuroMRD guidelines and lead to a similar quantitative range and sensitivity for the two detected gene rearrangements.”

They suggested that multiplex MP PCR could also be useful for detecting other DNA markers, such as in neuroblastoma.

Although there is the potential for MP PCR to be the new standard in personalized MRD monitoring, it still needs to be clinically validated in a diagnostic study of a representative cohort before it can be used routinely in the clinical environment, they noted.

"Cancer is a fatal disease from which not every patient can be cured," Eckert said. "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."

Reference

Kipf E, Schlenker F, Borst N, et al. Advanced minimal residual disease monitoring for acute lymphoblastic leukemia with multiplex mediator probe PCR. J Mol Diagn. 2022;24(1):57-68. doi:10.1016/j.jmoldx.2021.10.001

https://www.ajmc.com/view/test-could-provide-earlier-identification-of-relapse-in-all