A groundbreaking stem cell-based test has demonstrated superior accuracy in predicting acute myeloid leukemia (AML) relapse following stem cell transplantation, potentially transforming post-transplant monitoring and early intervention strategies for patients with this aggressive blood cancer.
Enhanced Predictive Power Over Traditional Methods
Research involving 360 AML patients who underwent allogeneic transplants between July 2018 and November 2019 revealed that a leukemia stem cell (LSC)-based test significantly outperformed conventional measurable residual disease (MRD) detection methods. The LSC-based approach, which identifies CD34+CD38− leukemia stem cells, demonstrated 52.4% sensitivity compared to 33.3% for traditional multiparameter flow cytometry (MFC) assays.
Patients with MRD detected by the LSC assay faced dramatically different outcomes. Those with detectable leukemia stem cells had a 49.7% five-year cumulative incidence of relapse compared to just 8.5% for patients without detectable LSCs. The survival disparities were equally striking, with five-year leukemia-free survival rates of 48.2% versus 84.4%, and overall survival rates of 59.7% versus 82.8%.
Superior Predictive Metrics and Earlier Detection
The LSC-based method demonstrated stronger predictive power across multiple statistical measures, achieving a higher concordance index (0.72 vs. 0.65) and Youden index (0.44 vs. 0.27) compared to traditional MFC-MRD testing. Perhaps most significantly for clinical intervention, the LSC assay predicted relapse substantially earlier, with a median lead time of 144 days versus 65 days for conventional flow cytometry.
LSC17 Score: From Discovery to Clinical Implementation
The development of this approach centers on the LSC17 score, a biomarker derived from leukemia stem cells that drive disease progression and relapse. These dormant stem cells possess properties that allow them to resist standard chemotherapy designed to target rapidly dividing cancer cells, explaining why cancer returns in patients despite achieving remission following treatment.
Dr. Jean Wang, Affiliate Scientist at the Princess Margaret, University Health Network and co-principal investigator, explains that the LSC17 score represents "the most powerful predictive and prognostic biomarker currently available for AML, and is the first stem cell-based biomarker developed in this way for any human cancer."
Rapid Clinical Translation
The research team identified the LSC17 score by analyzing leukemia stem cell properties from blood or bone marrow samples of 78 AML patients, combined with molecular profiling technology measuring gene expression. Stanley W. K. Ng, senior PhD candidate at the University of Toronto and co-lead author, used rigorous statistical approaches to develop the "stemness score" using patient data from multiple international collaborators.
The test has been successfully adapted to the NanoString technology platform, enabling rapid clinical implementation. Dr. Wang emphasizes that the fast turnaround time for measuring the LSC17 score on the NanoString system will be crucial for clinical adoption, potentially providing results within one to two days of diagnosis.
Clinical Impact and Future Applications
For AML, one of the most deadly types of leukemia and the most common acute leukemia in adults, these findings offer significant clinical promise. With more than 1,200 new cases annually in Canada and five-year survival rates ranging between 20-30%, the ability to rapidly identify high-risk patients could fundamentally change treatment approaches.
The study authors note that using the LSC17 score to identify high-risk patients with predicted resistant disease "provides clinicians with a rapid and powerful tool to identify AML patients who are less likely to be cured by standard therapy and who could be enrolled in trials evaluating novel upfront or post-remission strategies."
Plans are underway to test the score in clinical trials at the Princess Margaret, which has implemented the NanoString system in its molecular diagnostic laboratory. The findings suggest that incorporating LSC-based MRD testing into post-transplant care could enable earlier clinical intervention and improved long-term outcomes for AML patients.
