Hematopoietic stem cell transplantation for patients with acute lymphoblastic leukemia and Down syndrome

Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

The remarkable improvement in the prognosis of children with acute lymphoblastic leukemia (ALL) has been mainly achieved through the administration of risk-adapted therapy, including allogeneic hematopoietic stem cell transplantation (HSCT). This paper reviews the current indications to HSCT in ALL children, as well as the type of donor and conditioning regimens commonly used. Finally, it will focus on future challenges in immunotherapy.

RECENT FINDINGS

As our comprehension of disease-specific risk factors improves, indications to HSCT continue to evolve. Future studies will answer the year-old question on the best conditioning regimen to be used in this setting, while a recent randomized controlled study fixed the optimal anti-thymocyte globulin dose in unrelated donor HSCT. HSCT, the oldest immunotherapy used in clinical practice, still represents the gold standard consolidation treatment for a number of pediatric patients with high-risk/relapsed ALL. New immunotherapies hold the promise of further improving outcomes in this setting.

Acute leukemia in a patient with 15q overgrowth syndrome

Overgrowth syndromes are rare genetic conditions which present as global or segmental hyperplasia and are sometimes associated with increased risk of malignancy. Trisomy of the terminal portion of 15q which includes the IGFR1 gene, produces a rare overgrowth phenotype that has been termed 15q overgrowth syndrome (15q OGS). Upregulation of IGF1R has long been implicated in oncogenesis of multiple cancer types, including acute leukemias, and has been shown to render cells more susceptible to other transforming events. To date, too few cases of 15q OGS have been reported to identify any cancer predisposition. We present a case of a 34-year-old female with intellectual disability, macrocephaly, and subtle dysmorphic features who was diagnosed with mixed phenotype acute leukemia (lymphoid and myeloid). Prior to initiation of therapy she was referred to medical genetics for further evaluation and was identified as having a chromosomal translocation resulting in a partial trisomy of chromosome 15q, consistent with 15q OGS. A review of the literature for cases of malignancy in individuals with increased copy number of 15q revealed only one other reported patient. Given the small number of reported individuals, we cannot rule out an increased risk of cancer associated with this chromosomal overgrowth syndrome. Although concerns have been raised regarding treatment feasibility in the setting of chromosomal disorders, the reported patient underwent successful treatment with allogeneic hematopoietic stem-cell transplant.

Factors Determining the Outcome of Hematopoietic Stem Cell Transplantation in Patients With Acute Lymphoblastic Leukemia at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia

Medical records of 82 patients with acute lymphoblastic leukemia (ALL) who underwent hematopoietic cell transplantation (HCT) at our institution from 2005 to 2011 were reviewed. Forty-five patients were male (54.8%). The median age at HCT was 7.46 years (range, 0.98 to 14.31 y), the median time to HCT after diagnosis was 12.56 months. Ten patients were below the age of 1 year (12%). All patients were in complete remission at the time of HCT. In 83 transplants, 64 patients received HCT from human leukocyte antigen-identical-related donors and 19 from other donors. Stem cell source was bone marrow in 65 (78%) and cord blood in 18 (22%). Five-year overall survival was 58.8% and event-free survival was 54.3%. The cumulative incidence of acute graft versus host disease was 4.8%±2.3% and of chronic graft versus host disease was 8.9%±3.2%. The median time to absolute neutrophil count and platelet recovery was 17 days (range, 12 to 43 d) and 28 days (range, 15 to 98 d), respectively. One patient acquired CMV infection after transplant. No one developed venoocclusive disease, hemorrhagic cystitis, or other complication. Patient's age at diagnosis, sex, donor's human leukocyte antigen status and sex, source of transplant and complete remission status at HCT did not affect overall survival and event-free survival. Our results show a favorable outcome to HCT for acute lymphoblastic leukemia patients comparable to published data, and no single factor was associated with superior outcome.

Philadelphia chromosome-positive acute lymphoblastic leukemia and Down syndrome

Children with Down syndrome (DS) are at high risk of developing acute lymphoblastic leukemia (ALL), but Philadelphia chromosome-positive (Ph+) ALL is rare in DS children. We report a case of Ph+ALL with DS complicated by chronic heart failure. Complete molecular remission was obtained after imatinib-combined chemotherapy, although infectious episodes during the neutropenic period worsened the heart condition. After two courses of intensification chemotherapy, the patient underwent reduced intensity stem cell transplantation from an HLA-identical sibling donor followed by post-transplant imatinib. The patient maintained molecular complete remission for >2 years. This case report is the first description of the safe and effective use of imatinib for DS-Ph+ALL. This case suggests the potential of molecular targeting therapy in DS-ALL, which is often complicated by congenital diseases, and the importance of treating DS-ALL while maintaining intensity and reducing treatment-related toxicity.

The biology, pathogenesis and clinical aspects of acute lymphoblastic leukemia in children with Down syndrome

Children with Down syndrome (DS) are at a 20-fold increased risk for acute lymphoblastic leukemia (DS-ALL). Although the etiology of this higher risk of developing leukemia remains largely unclear, the recent identification of CRLF2 (cytokine receptor like factor 2) and JAK2 mutations and study of the effect of trisomy of Hmgn1 and Dyrk1a (dual-specificity tyrosine phosphorylation-regulated kinase 1A) on B-cell development have shed significant new light on the disease process. Here we focus on the clinical features, biology and genetics of ALL in children with DS. We review the unique characteristics of DS-ALL on both the clinical and molecular levels and discuss the differences in treatments and outcomes in ALL in children with DS compared with those without DS. The identification of new biological insights is expected to pave the way for novel targeted therapies.