Acute Leukemia in Down Syndrome Children in Hong Kong: Retrospective Review.

BACKGROUND: Children with Down syndrome (DS) are at higher risk of developing acute leukemia. Treatment continues to evolve as we accumulate better understanding of the distinctive clinical and biological features of acute leukemia in DS patients. PROCEDURE: A retrospective review of the clinical features, treatment outcomes, and survival of DS children with acute leukemia in Hong Kong from 1993 to 2013 was conducted. Patients were identified from the registry of the Hong Kong Pediatric Hematology and Oncology study group. RESULTS: This cohort included a total of 29 patients with DS. Ten were diagnosed with acute lymphoblastic leukemia and 19 had acute myeloid leukemia (AML). The mean follow-up duration was 8.3 years (range, 0.6 mo to 18.1 y). The 5-year overall survival and event-free survival for DS-acute lymphoblastic leukemia and DS-AML were 65.6%, 54.9%, 89.5%, and 89.5%, respectively. CONCLUSIONS: The clinical characteristics and treatment outcomes of DS patients with acute leukemia in Hong Kong were comparable with results from other international study groups. Patients with DS-AML had a better prognosis.

The incidence, risk factors, and outcomes of symptomatic avascular necrosis of bone among Chinese pediatric patients with acute lymphoblastic leukemia.

BACKGROUND: Avascular necrosis (AVN) of bone is a debilitating complication of pediatric patients with acute lymphoblastic leukemia (ALL). While it is extensively studied and reported in Western population, studies focused on Orientals are limited. This study aims to evaluate the incidence, risk factors, and clinical outcomes of AVN among Chinese children with ALL. METHODS: This study is a retrospective, territory-wide population-based cohort study of pediatric patients with ALL enrolled on one of the three consecutive ALL study protocols (ALL-IC-BFM 2002, CCLG-ALL 2008, and CCCG-ALL 2015). RESULTS: A total of 24 out of 533 pediatric subjects with ALL (4.5%) had symptomatic AVN. Age was the single most important risk factor associated with the development of AVN. Only three patients were below age of 10 at the time of diagnosis of ALL. The incidences of AVN in patients aged above and below 10 years were 18.2% ± 3.6% and 0.8% ± 0.5%, respectively, and were significantly different (p < 0.005). Treatment protocol, immunophenotype, and gender were not predictive of AVN. Among the 24 patients, five required orthopedic interventions in view of progressive and severe disease. For subjects with hip joints involvement, follow-up assessments showed 12 of 22 hip joints had radiological progression over a median duration of 3.63 years. Seventeen of them did not have pain at the latest follow-up and among patients with pain (n = 7), five did not experience any limitation on activities of daily living while two required use of walking aids or wheelchair. CONCLUSION: The incidence of symptomatic AVN in Chinese ALL patients was comparable to other studies in Western population. Adolescent age more than 10 years old was recognized to be the most important factor for development of AVN. Significant proportion of patients had radiological progression over time with a small percentage of subjects had daily activities affected.

Pharmacogenomic Profiling of Pediatric Acute Myeloid Leukemia to Identify Therapeutic Vulnerabilities and Inform Functional Precision Medicine.

Despite the expanding portfolio of targeted therapies for adults with acute myeloid leukemia (AML), direct implementation in children is challenging due to inherent differences in underlying genetics. Here we established the pharmacologic profile of pediatric AML by screening myeloblast sensitivity to approved and investigational agents, revealing candidates of immediate clinical relevance. Drug responses ex vivo correlated with patient characteristics, exhibited age-specific alterations, and concorded with activities in xenograft models. Integration with genomic data uncovered new gene-drug associations, suggesting actionable therapeutic vulnerabilities. Transcriptome profiling further identified gene-expression signatures associated with on- and off-target drug responses. We also demonstrated the feasibility of drug screening-guided treatment for children with high-risk AML, with two evaluable cases achieving remission. Collectively, this study offers a high-dimensional gene-drug clinical data set that could be leveraged to research the unique biology of pediatric AML and sets the stage for realizing functional precision medicine for the clinical management of the disease. SIGNIFICANCE: We conducted integrated drug and genomic profiling of patient biopsies to build the functional genomic landscape of pediatric AML. Age-specific differences in drug response and new gene-drug interactions were identified. The feasibility of functional precision medicine-guided management of children with high-risk AML was successfully demonstrated in two evaluable clinical cases. This article is highlighted in the In This Issue feature, p. 476.

CD9 blockade suppresses disease progression of high-risk pediatric B-cell precursor acute lymphoblastic leukemia and enhances chemosensitivity.

CD9 has been implicated in cancer progression but its prognostic relevance and therapeutic potential in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are largely unknown. In a cohort of pediatric BCP-ALL patients, we found that CD9+ cases had a significantly lower 5-year relapse-free survival rate than CD9- cases. Multivariate analysis demonstrated that CD9 positivity independently predicted inferior survival outcomes, and could be applied with established prognostic features, including prednisone response and cytogenetic status, to refine patient stratification. Administration of CD9 antibody substantially suppressed disease progression in NOD/SCID mice xenografted with CD9+ cell lines and primary leukemic blasts from patients with high-risk and refractory BCP-ALL, without compromising hematopoietic stem cell engraftment. Combination of anti-CD9 with conventional chemotherapy further reduced leukemic burden and prolonged animal survival. Mechanistically, CD9 blockade inhibited leukemic cell proliferation, induced G0/G1 cell cycle arrest, activated p38, and enhanced chemotherapeutic agent-induced apoptosis. Further, CD9 physically interacted with integrin very late antigen-4, regulated affinity to vascular cell adhesion molecule-1, and was involved in leukemia-stroma interaction. Collectively, our study established CD9 as a new prognostic marker, validated the preclinical efficacy of CD9 antibody, and laid the foundation for clinical development of CD9-targeted therapy for high-risk and refractory pediatric BCP-ALL.