▲ Professor Hyery Kim from the Division of Pediatric Hematology and Oncology at Asan Medical Center

Acute lymphoblastic leukemia (ALL) is the most common type of blood cancer in children. Advances in treatment have significantly improved survival rates, but in some cases, even when patients appear to be cured, a small number of cancer cells remain in the body, putting them at high risk of relapse. This condition is called minimal residual disease (MRD). Recently, bone marrow tests have been used to measure MRD levels and adjust the intensity of chemotherapy accordingly.

A research team led by Professor Hyery Kim from the Division of Pediatric Hematology and Oncology at Asan Medical Center recently reported that, among 212 pediatric acute lymphoblastic leukemia patients treated at our hospital between January 2013 and June 2023, those with high MRD levels showed a significantly improved five-year event-free survival rate when treatment intensity was increased.

The research team measured MRD levels at each stage of treatment and switched to stronger chemotherapy if the level was more than 0.1%. Among 21 patients who tested MRD-positive after induction therapy (the first phase), 12 received intensified treatment. Their five-year event-free survival rate was 90%, compared with only 19% in those who did not receive intensified therapy, which is more than a four-fold difference. Similarly, after consolidation therapy (the second phase), MRD-positive patients who continued with standard treatment had a 75.4% survival rate, whereas those who received intensified treatment achieved a 95.2% survival rate. Importantly, no severe complications were observed beyond what is typically expected with chemotherapy.

In 2021, Asan Medical Center introduced next-generation sequencing (NGS)-based on MRD testing, which is more than 100 times more sensitive than conventional flow cytometry and enables more precise treatment planning. As a result, since 2015, the cure rate for pediatric acute lymphoblastic leukemia patients at our hospital has exceeded 97%.

These findings were recently published in the international journal ‘Blood Research.’