Acute lymphoblastic leukemia (ALL) is the most common children’s cancer. A study by the School of Medicine at CUHK confirmed that a protein called CD9 is closely related to the prognosis of children with ALL and can be used as an independent biomarker to predict the risk of recurrence, helping to identify high-risk patients and find appropriate treatment options as early as possible to reduce the risk of recurrence and improve survival rate.
According to CUHK, ALL accounts for about 30 percent of all children’s cancers, 90 percent of which are B-cell leukemia (B-ALL), and 10 percent are T-cell leukemia (T-ALL). Currently, there are about 50 new cases in Hong Kong every year.
Doctors will adjust the intensity of chemotherapy according to the patient’s disease risk to balance drug efficacy and toxicity. Although the overall cure rate of ALL has reached 90 percent, the treatment effects of patients still vary greatly. Therefore, the CUHK team hopes to find reliable biomarkers to provide prognostic judgment and formulate more appropriate treatment plans.
In 2020, the CUHK team discovered that a protein called CD9 may become a biomarker that reveals the prognosis of children with ALL. CUHK, together with teams from Shanghai Children’s Medical Center and St. Jude Children’s Research Hospital, collected 3,781 ALL cases that received unified treatment from 20 hospitals and medical centers across the country from 2015 to 2019, and analyzed their CD9 expression, and clinical and pathological data. A retrospective study analysis was conducted to understand how CD9 affects ALL prognoses.
The results showed that 5 percent of B-ALL patients showed widespread high CD9 expression, while only 27.9 percent of T-ALL patients were CD9 positive; among B-ALL patients, those who were CD9 positive had a worse prognosis than those who were CD9 negative. The incident survival rate is lower, and the cumulative relapse rate is twice as high, but the same situation has not been seen in T-ALL patients.
The team analyzed the patients’ disease risk levels and found that B-ALL patients with moderate to high disease risk and CD9-positive were in the most dangerous situation, with a cumulative recurrence rate of as high as 23.1 percent within five years, while CD9-negative patients were only 10.5 percent. Patients with minimal residual disease after chemotherapy or with BCR-ABL1 mutations will have a significantly increased recurrence rate if they are also CD9 positive.
Assistant Professor Leung Kam-tong from the Department of Pediatrics, Faculty of Medicine, CUHK, said that detecting whether CD9 is carried on the surface of cancer cells can help identify children with ALL who are at the highest risk of recurrence. He suggested that CD9 be included in routine children’s cancer testing projects to provide new guidelines for risk stratification and treatment of children with ALL.
