Personalized Treatment Targeting 'Residual Cancer Cells' in Pediatric Leukemia Raises Survival Rate Fourfold

Adjusting Chemotherapy Intensity Based on Minimal Residual Disease Levels
Five-Year Event-Free Survival Rate Improves from 19% to 90%
Hyeri Kim: "Survival Rates Can Be Increased Even for High-Risk Patients"

Pediatric acute lymphoblastic leukemia (ALL), the most common blood cancer in children, is characterized by the excessive proliferation of abnormal lymphoid precursor cells in the bone marrow, which suppresses the production of normal blood cells and leads to symptoms such as anemia and bleeding. Advances in treatments like chemotherapy have significantly improved survival rates. However, some patients, despite appearing to be cured, still have a small number of cancer cells remaining in their bodies, putting them at high risk of relapse. The effectiveness of personalized treatment that adjusts the intensity of chemotherapy based on the measurement of this 'minimal residual disease (MRD)' has now been confirmed.

Hyeri Kim, Professor, Department of Pediatric Hematology-Oncology, Asan Medical Center, Seoul

Asan Medical Center announced on September 1 that the research team led by Professor Hyeri Kim from the Department of Pediatric Hematology-Oncology analyzed around 200 patients treated for pediatric acute lymphoblastic leukemia over the past 10 years. They found that in patients with high MRD levels, increasing the intensity of treatment raised the five-year event-free survival rate from the previous 19% to 90%, more than a fourfold improvement.

At each stage of treatment for pediatric acute lymphoblastic leukemia, including the first-line remission induction therapy and the second-line consolidation therapy, MRD levels were checked. If the MRD level was 0.1% or higher, the treatment was intensified by using more potent drugs or adding additional chemotherapy cycles, thereby improving the survival rate of patients at high risk of relapse.

Professor Kim's team conducted the study on 212 pediatric acute lymphoblastic leukemia patients treated at Asan Medical Center from January 2013 to June 2023. All patients had their MRD levels measured at each stage of treatment, and if the result was positive at 0.1% or higher, they were switched to more intensive chemotherapy.

After the first-line remission induction therapy, 21 patients tested positive for MRD, and 12 of them received intensified treatment. As a result, the five-year event-free survival rate was 19% for those who did not receive intensified therapy, but 90% for those who did, indicating a more than fourfold increase in survival.

Similarly, among patients who tested positive for MRD after the second-line consolidation therapy, those who did not receive intensified treatment had a survival rate of 75.4%, while those who received intensified treatment had a survival rate of 95.2%. Furthermore, no severe side effects, other than the usual side effects of chemotherapy, were observed in the group receiving intensified therapy.

Since 2021, Asan Medical Center has introduced next-generation sequencing (NGS)-based MRD testing, which is over 100 times more sensitive than conventional flow cytometry. This advancement has made it possible to detect even minute quantities of leukemia cells that previous tests might have missed, enabling the development of more precise treatment plans based on MRD levels. As a result, the cure rate for pediatric acute lymphoblastic leukemia patients treated at Asan Medical Center since 2015 has surpassed 97%.

Professor Kim stated, "Through this study, we confirmed that adjusting treatment intensity based on MRD levels can significantly improve the survival rate of pediatric leukemia patients at high risk of relapse. We will continue to closely monitor treatment responses and strive to further increase the cure rate for pediatric leukemia."

The results of this study were recently published in the international journal 'Blood Research'.