CD200, CD56 Expression Predict Poor Prognosis in Pediatric B-ALL

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Children with B-cell acute lymphoblastic leukemia (B-ALL) who were positive for CD200 and/or CD56 expression had significantly poorer overall survival (OS) and disease-free survival (DFS), according to findings from a small study.

After follow-up of 24 months, cumulative OS (P = .032) and DFS (P = .049) was significantly longer for CD200-negative patients compared with those expressing CD200. Similarly, CD56-expressing patients had poor OS (P = .01) and shorter DFS (P = .01) compared with CD-56 negative patients.

Pediatric ALL is the most common childhood cancer and worldwide incidence is increasing by 1.4% every year. The disease is most often diagnosed in children aged 1 to 4 years and is slightly more common in boys. In Egypt, where the study was conducted, the annual incidence is approximately 4 Cases per 100,000 children per year according to the National Cancer Institute and Cairo University.

Researchers analyzed pretreatment bone marrow and peripheral blood specimens obtained from 43 patients treated at Mansoura University Oncology Center at Mansoura University in Mansoura, Egypt. All patients received 5 weeks of induction chemotherapy followed by an 8-week consolidation phase, and a 2-year maintenance phase.

Twenty-eight patients (65%) were positive for CD200 expression. Five (11.6%) expressed CD56 and 2 patients expressed both. Platelets count was lower in CD200-positive patients compared with negative expressers in all cases. However, CD56 expression was associated with a higher median platelet count compared with CD56-negative patients. Investigators also observed significant association between CD200 positivity and CD34 positivity (57.1%).

Patients were classified as low- (58.8%), intermediate- (35.3%), or high-risk (5.9%). Average age was 4.5 years (range, 2-18) for CD200-negative patients and 5.9 years (range, 2-18) for CD200-positive patients. Eleven CD200-negative patients were male and 4 were female, compared with 14 for both among CD200-positive patients.

Among CD56-negative patients, the average age was 5.1 years (range, 2-18). Twenty-two patients were boys and 16 were girls. Average age was 8 years (range, 2-18) among CD56-positive patients. Three patients were boys and 2 were girls.

Induction remission (IR) rate was significantly higher in CD200-negative patients compared with CD200-positive (93.3% vs 67.8%). Similarly, IR was significantly lower in CD56-positive versus CD56-negative patients (43% vs 88.8%). The two patients who showed combined expression of CD200 and CD56 did not respond to chemotherapy and died during induction. These 2 patients also experienced more pain and increased frequency of splenomegaly, and displayed the lowest platelet count.

Investigators performed Cox regression analysis for prediction of survival times in all studied ALL patients, using age, sex, BM blasts, cytogenetic abnormalities, induction remission response (CR), CNS infiltration, LDH, and CD200 and CD56 expression as covariates. CD200 and CD56 positive expression, cytogenetic abnormalities, and CR were significantly associated with OS in pediatric ALL multivariate analyses. Only CD200 and CD56 expression were considered independent predictors for poor prognosis in DFS.

Investigators noted that CD200 expression was not significantly associated with age, sex, male gender, splenomegaly, or lower hemoglobin, but was significantly associated with lower platelet count.

Aref S, Azmy E, El-bakry K, et al. Prognostic impact of CD200 and CD56 expression in pediatric B-cell acute lymphoblastic leukemia patients [published online November 16, 2017. Pediatr Hematol Oncol. doi: 10.1080/08880018.2017.1363836.