Myelodysplastic syndromes in children. A critical review of the clinical manifestations and management

Transient juvenile myelomonocytic leukemia in the setting of PTPN11 mutation and Noonan syndrome with secondary development of monosomy 7

Juvenile myelomonocytic leukemia (JMML) is a rare childhood neoplasm with poor prognosis except in the setting of Noonan syndrome, where prognosis is generally favorable. We present the case of a child with JMML in the setting of germline PTPN11 mutation and Noonan syndrome with suspected secondary development of monosomy 7 in the bone marrow. Diagnosed shortly after birth, she has been managed with active surveillance alone. Myeloblast percentages initially fluctuated; however, bone marrow biopsy at 4 years of age showed spontaneous remission despite persistence of the monosomy 7 clone, supporting a cautious approach in similar cases.

Myelodysplastic syndromes in children: a critical review of issues in the diagnosis and classification of 887 cases from 13 published series

CONTEXT

Pediatric myelodysplastic syndromes (MDSs) are uncommon disorders, which may be difficult to diagnose, particularly in the absence of increased blasts. Pediatric MDSs have several unique features including their association with inherited/constitutional disorders in approximately one third of patients. The classification of pediatric MDSs has undergone significant evolution in the past 20 years.

OBJECTIVE

To critically review existing classifications of pediatric MDSs and to evaluate their applicability on previously published large series.

DATA SOURCES

Previously published pediatric MDS series containing more than 10 patients from the English literature between 1982 and 2005.

CONCLUSIONS

Data were available on 887 patients from 13 published series. Most cases (68.7%) were idiopathic/de novo, 23.9% were associated with constitutional/inherited disorder, and 7.4% were therapy related. Approximately 10% of cases could not be classified by the French-American-British classification. Eighty-seven percent of unclassified cases were appropriately classified using the World Health Organization classification (2001), whereas 96% of them were classified with the modified World Health Organization classification for pediatric MDSs (2003). The impact of cytogenetics and constitutional/inherited disorders on the biology and outcome of the disease needs to be studied further.

Comparison of childhood myelodysplastic syndrome, AML FAB M6 or M7, CCG 2891: report from the Children's Oncology Group

BACKGROUND

Myelodysplastic syndromes (MDS), acute erythroleukemia (FAB M6), and acute megakaryocytic leukemia (FAB M7) have overlapping features.

PROCEDURE

Children without Down syndrome or acute promyelocytic leukemia who were newly diagnosed with primary myelodysplastic syndrome or acute myeloid leukemia (AML) M6 or M7 were compared to children with de novo AML M0-M5. All children were entered on the Children's Cancer Group therapeutic research study CCG 2891.

RESULTS

The presentation and outcomes of the 132 children diagnosed with MDS (60 children), AML FAB M6 (19 children), or AML FAB M7 (53 children) were similar. Children with AML FAB M7 were diagnosed at a significantly younger age (P = 0.001). Children with MDS, M6, or M7 had significantly lower white blood cell (WBC) counts (P = 0.001), lower peripheral blast counts (P < 0.001), and an increased frequency of -7/7q- (P = 0.003) at presentation. All three groups had significantly inferior overall survival (OS) (P < 0.001) and event free survival (P < 0.001) compared with the 748 children diagnosed with AML FAB M0-M5 when assessed from entry on study. This poor survival was largely attributable to induction death and failure. However, when assessed from successful completion of induction therapy, the 5-year OS (P = 0.090)(49.1 vs. 56.9%) and disease-free survival (DFS) (P = 0.113)(38.0 vs. 46.3%) therapy were not significantly different from other children with AML.

CONCLUSIONS

Childhood AML FAB M6 and AML M7 resemble MDS in presentation, poor induction success rates, and outcomes.

Identification of an immunogenic CD8+ T-cell epitope derived from gamma-globin, a putative tumor-associated antigen for juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder. Although allogeneic stem cell transplantation can induce long-term remissions, relapse rates remain high and innovative approaches are needed. Since donor lymphocyte infusions have clinical activity in JMML, T-cell-mediated immunotherapy could provide a nonredundant treatment approach to compliment current therapies. Gamma-globin, an oncofetal protein overexpressed by clonogenic JMML cells, may serve as a target of an antitumor immune response. We predicted 5 gamma-globin-derived peptides as potential human leukocyte antigen (HLA)-A2 restricted cytotoxic T lymphocyte (CTL) epitopes and showed that 4 (g031, g071, g105, and g106) bind A2 molecules in vitro. Using an artificial antigen-presenting cell (aAPC) that can process both the N- and C-termini of endogenously expressed proteins, we biochemically confirmed that g105 is naturally processed and presented by cell surface A2. Furthermore, g105-specific CD8(+) CTLs generated from A2-positive healthy donors were able to specifically cytolyze gamma-globin(+), but not gamma-globin(-) JMML cells in an A2-restricted manner. These results suggest that this aAPC-based approach enables the biochemical identification of CD8(+) T-cell epitopes that are processed and presented by intact cells, and that CTL immunotherapy of JMML could be directed against the gamma-globin-derived epitope g105.

Poor clinical course in a child with myelodysplastic syndrome and del(13)(q14q22)

Myelodysplastic syndromes (MDS) are rare in children, representing 3% or less of all hematopoietic malignancies. Cytogenetic abnormalities, such as -7/7q-, +8, and +21 have been reported in 55-80% of children with MDS. Cytogenetic studies have an important impact on diagnosis, treatment selection, and monitoring therapeutic protocols when combined with morphologic data. We report on a pediatric case of MDS with the presence of the rare clonal abnormality del(13)(q14q22) which underwent a malignant transformation to leukemia and ran a very poor clinical course.

Allogeneic bone marrow transplantation for juvenile myelomonocytic leukemia: a single center experience of 23 patients

Juvenile myelomonocytic leukemia (JMML) is a childhood leukemia for which allogeneic BMT is the only curative therapy. At our pediatric stem cell transplantation unit, we performed 26 BMTs in 23 children (age 0.5–12.7 years). Conditioning was CY/TBI based (1980–1996, n=14) or BU/CY/melphalan based (1996–2001, n=9). Donors were HLA-identical siblings (n=11), unrelated volunteers (n=9) or mismatched family members (n=3). A total of 10 patients survive in CR (median follow-up 6.8 years, range 3.1–22.2 years). Relapse or persistent disease was observed in eight and two patients, respectively. Nine of these patients died, one achieved a second remission following acute nonlymphatic leukemia chemotherapy (duration to date 5.3 years). Transplant-related mortality occurred in four patients. Overall survival at 5 and 10 years was 43.5%. Using T-cell-depleted, one-antigen mismatched unrelated donors was the only significant adverse factor associated with relapse in multivariate analysis (P=0.039, hazard ratio 4.9). Together with a trend towards less relapse in patients with graft-versus-host-disease and in patients transplanted with matched unrelated donors, this suggests a graft-versus-leukemia effect of allogeneic BMT in JMML.

Therapy-related myelodysplastic syndrome in childhood: A retrospective study of 36 patients in Japan

We report here a retrospective analysis of 36 children with therapy-related myelodysplastic syndrome (t-MDS) diagnosed between 1990 and 1999 in Japan. Their median age was 7.7 years and the median latency period for the development of t-MDS was 38.5 months. The primary tumors were hematologic in 15 of the cases and nonhematologic in 21. Chromosomal abnormalities were detected in 32/34(94%) patients: abnormalities of chromosomes 5and/or 7 in 41% and notably, 11q23 abnormalities in 31%. The prognosis of children with t-MDS was very poor as compared to children with primary MDS (5 year survival: 16% versus 54%, p<0.0001).