Docetaxel-Based Neoadjuvant Chemotherapy Followed by En Bloc Resection for Esophageal Adenocarcinoma: A 15-Year Retrospective Analysis from a Regional Upper Gastrointestinal Cancer Network.

BACKROUND: Real-world, long-term survival outcomes of neoadjuvant, docetaxel-based therapy for esophageal and junctional adenocarcinoma are lacking. This study describes the long-term survival outcomes of patients with esophageal and junctional adenocarcinoma treated with neoadjuvant docetaxel-based chemotherapy and en bloc transthoracic esophagectomy. METHODS: A retrospective cohort analysis of a prospectively maintained database from a regional upper gastrointestinal cancer network in Quebec, Canada, was performed. From January 2007 to December 2021, all patients with locally advanced (cT3 and/or N1) esophageal/Siewert I/II adenocarcinoma treated with neoadjuvant DCFx3 (Docetaxel/Cisplatin/5FU) or FLOTx4 (5FU/Leucovorin/Oxaliplatin/Docetaxel) and transthoracic en bloc esophagectomy were identified. Postoperative, pathological, and survival outcomes were compared. RESULTS: Overall, 236 of 420 patients met the inclusion criteria. Tumor location was esophageal/Siewert I/Siewert II (118/33/85), most were cT3-4 (93.6%) and cN+ (61.0%). DCF and FLOT were used in 127 of 236 (53.8%) and 109 of 236 (46.2%). All neoadjuvant cycles were completed in 87.3% with no difference between the regimens. Operative procedures included Ivor Lewis (81.8%), left thoraco-abdominal esophagectomy (10.6%) and McKeown (7.6%) with an R0 resection in 95.3% and pathological complete response in 9.7% (DCF 12.6%/FLOT 6.4%, p = 0.111). The median lymph node yield was 32 (range 4-79), and 60.6% were ypN+. Median follow-up was longer for the DCF group (74.8 months 95% confidence interval [CI] 4-173 vs. 37.8 months 95% CI 2-119, p <0.001. Overall survival was similar between the groups (FLOT 97.3 months, 78.6-115.8 vs. DCF 92.9, 9.2-106.5, p = 0.420). CONCLUSIONS: Neoadjuvant DCF and FLOT followed by transthoracic en bloc resection are both highly effective regimens for locally advanced esophageal adenocarcinoma with equivalent survival outcomes despite high disease load.

Association between busulfan exposure and outcome in children receiving intravenous busulfan before hematopoietic stem cell transplantation.

BACKGROUND AND OBJECTIVE: Intravenous (IV) busulfan (Bu) combined with therapeutic drug monitoring-guided dosing is associated with better event-free survival (EFS), lower transplant-related mortality. But optimal target steady-state concentration (Css) of Bu in children undergoing hematopoietic stem cell transplantation (HSCT) remains unclear. This study aimed to evaluate the relation between Css of Bu and clinical outcomes in children receiving Bu before HSCT. METHODS: This study includes 75 children receiving IV Bu in 16 doses, with first dose assigned based on age. Bu first-dose pharmacokinetic parameters were estimated from Bu plasma concentrations measured at 6 time points by high-performance liquid chromatography. Doses were adjusted at the fifth dose to a target Css of 600-900 ng/mL. Cumulative incidence of overall survival (OS), EFS, transplant-related mortality, acute graft-versus host disease (aGVHD), and other toxicities in relation to Css of Bu were analyzed using Kaplan-Meier curves in univariate and Cox's proportional hazards model in multivariate analysis. RESULTS: After the first dose, median Css was 578 (325-1227) ng/mL. Forty-one patients had Bu IV dose increased by > 10%. Neutrophil and platelet recoveries, grade 2-4 aGVHD, and nonrelapse mortality (NRM) incidences were 90%, 91%, 12%, and 13%, respectively. Relapse incidence was 33%. Incidence of veno-occlusive disease, hemorrhagic cystitis, and lung toxicities were 13%, 24%, and 7%, respectively. OS and EFS were 70% and 58%. First-dose Bu Css >600 ng/mL was associated with a higher NRM (P < 0.001) and grade 2-4 aGVHD (P = 0.04), a lower EFS (P < 0.001), and OS (P = 0.001). CONCLUSIONS: This study demonstrated a significant association between the first-dose pharmacokinetics of Bu and NRM, OS, and EFS. Bu therapeutic drug monitoring provides information that potentially influences outcomes of HSCT in pediatric patients.

CD8(+) T-cell reconstitution in recipients of umbilical cord blood transplantation and characteristics associated with leukemic relapse.

Recipients of umbilical cord blood (UCB) transplantation (UCBT) face a high risk of morbidity and mortality related to opportunistic infections (OI) and leukemic relapse. To understand the molecular basis of these UCBT-related complications, the characteristics of UCB-derived antigen-specific CD8(+) T cells were examined in a group of pediatric UCBT recipients. Compared with the UCB graft inoculum and the late post-UCBT period (12-36 months), declining clonal diversity of UCB-derived CD8(+) T cells specific for the Melan-A(26-35) A27L peptide and high frequencies of PD-1-expressing CD8(+) T cells were observed in the first 3 months after UCBT, a period during which OIs are most frequent. The CD8(+) T-cell compartment predominantly comprised CD45RA(+) CCR7(-) terminally differentiated effector-memory T cells until 6 months after UCBT, at which time the polyfunctionality of antigen-specific CD8(+) T cells was reestablished. Finally, the frequency of PD-1(+) CD8(+) T cells was significantly higher in subjects who subsequently experienced leukemic relapse. This study informs the biologic properties of UCB-derived CD8(+) T cells and provides a rationale for the characteristics of UCBT in terms of immune reconstitution and OI. These results also suggest that the elevated frequency of PD-1(+) CD8(+) T cells could be associated with leukemic relapse in pediatric UCBT recipients.

Multicenter survey on the outcome of transplantation of hematopoietic cells in patients with the complete form of DiGeorge anomaly.

Seventeen patients transplanted with hematopoietic cells to correct severe T lymphocyte immunodeficiency resulting from complete DiGeorge anomaly were identified worldwide, and retrospective data were obtained using a questionnaire-based survey. Patients were treated at a median age of 5 months (range, 2-53 months) between 1995 and 2006. Bone marrow was used in 11 procedures in 9 cases: 6 from matched unrelated donors, 4 from human leukocyte antigen (HLA)-identical siblings, and one haploidentical parent with T-cell depletion. Unmobilized peripheral blood was used in 8 cases: 5 from HLA-identical siblings, one from a matched unrelated donor, one from an HLA-identical parent, and one unrelated matched cord blood. Conditioning was used in 5 patients and graft-versus-host disease prophylaxis in 11 patients. Significant graft-versus-host disease occurred in 9 patients, becoming chronic in 3. Median length of follow-up was 13 months, with transplantation from HLA-matched sibling showing the best results. Median survival among deceased patients (10 patients) was 7 months after transplantation (range, 2-18 months). The overall survival rate was 41%, with a median follow-up of 5.8 years (range, 4-11.5 years). Among survivors, median CD3 and CD4 counts were 806 (range, 644-1224) and 348 (range, 225-782) cells/mm(3), respectively, CD4(+)/CD45RA(+) cells remained very low, whereas mitogen responses were normalized.

Impact of storage temperature and processing delays on cord blood quality: discrepancy between functional in vitro and in vivo assays.

BACKGROUND: Optimal conditions of cord blood (CB) storage, processing, cryopreservation, and thawing are critical for banking and transplantation. Nevertheless, standardized procedures are still awaited. STUDY DESIGN AND METHODS: We evaluated the impact of preprocessing storage and temperature on recovery, viability, and functional differentiation capacities of hematopoietic progenitor cells. We compared units stored at room temperature (RT) or at 4 °C for 72 hours before cryopreservation to units processed shortly after collection (<12 hr). RESULTS: Postthaw results showed similar in vitro characteristics between immediate processing and 4 °C storage for cell recovery and viability, both significantly higher than RT storage. Surprisingly, we demonstrated that storage of CB units at RT before processing and cryopreservation profoundly altered in vivo hematopoietic reconstitution in mice, although in vitro hematopoietic colony-forming unit potential was unaltered. CONCLUSION: Our findings challenge current CB storage practices and suggest standard in vitro quality assessments may not always be indicative of CB engraftment potential.

Umbilical cord blood T cells respond against the Melan-A/MART-1 tumor antigen and exhibit reduced alloreactivity as compared with adult blood-derived T cells.

Umbilical cord blood (UCB) is increasingly used as a source of hematopoietic progenitor cells to treat a variety of disorders. UCB transplant is associated with comparatively reduced incidence of graft-versus-host disease, robust graft versus leukemia effect, and relatively high incidence of opportunistic infections, three processes in which donor-derived T lymphocytes are known to be predominantly involved. To examine the differential functionality of UCB T cells, CD8(+) T cells specific for the melanoma-associated HLA-A2-restricted Melan-A(26-35) A27L peptide were isolated from HLA-A2(+) and HLA-A2(-) UCB samples and HLA-A2(+) and HLA-A2(-) adult peripheral blood using A2/Melan-A tetramers. In UCB samples, A2/Melan-A(+) CD8(+) T cells were detected at a frequency of 0.04%, were more frequent in HLA-A2(+) UCB, and were polyclonal and mostly naive. Consistent with Ag-driven expansion, the frequency of A2/Melan-A(+) CD8(+) T cells was increased following stimulation with cognate peptide or polyclonal activation, they acquired cell-surface markers reflective of effector/memory differentiation, their TCR repertoire became oligoclonal, and they expressed cytolytic activity and produced IFN-gamma. Although functional properties of A2/Melan-A(+) CD8(+) T cells derived from HLA-A2(+) UCB resembled those of HLA-A2(+) adult peripheral blood, they were more likely to reach terminal differentiation following polyclonal stimulation and produced less IFN-gamma in response to cognate peptide. A2/Melan-A(+) CD8(+) T cells from HLA-A2(-) UCB were poorly cytolytic, produced little IFN-gamma, and were predominantly monofunctional or nonfunctional. These properties of UCB-derived CD8(+) T cells could contribute to the reduced incidence of graft-versus-host disease and heightened incidence of opportunistic infections observed following UCB transplant.

Secondary pulmonary alveolar proteinosis after unrelated cord blood hematopoietic cell transplantation.

PAP is a rare alveolointerstitial lung disorder characterized histologically by the intra-alveolar accumulation of eosinophilic and PAS-positive material. We observed two cases of PAP after unrelated CB hematopoietic progenitor cell transplantation in children with ALL. No antagonist activity toward GM-CSF was identified in the patient tested. The putative multifactorial PAP etiology is discussed. This potentially curable condition should be considered in a CB allograft recipient with alveolointerstial lung disorder.

Higher dose imatinib for children with de novo chronic phase chronic myelogenous leukemia: a report from the Children's Oncology Group.

PURPOSE: To determine the efficacy of imatinib in children with newly diagnosed chronic phase (CP) chronic myelogenous leukemia (CML). METHODS: This was an open label, multi-center phase II clinical trial. Courses were defined as consecutive 28-day intervals. Oral imatinib was administered daily at 340 mg/m² without interruption in the absence of toxicity. RESULTS: Fifty-one children received 978 28-day courses of imatinib. The most common toxicities encountered were hematologic. Forty-one patients (80%) achieved a complete hematologic response by the end of course 2. Nineteen children (38%) obtained a complete cytogenetic response (CCyR) at the end of course 3. Overall, 72% achieved CCyR at a median time of 5.6 months. The rate of complete molecular response (>3 log reduction) was 27%. Progression-free and overall survival at 3 years were 72% ± 6.4% and 92% ± 3.9%, respectively. CONCLUSIONS: Daily oral imatinib at a dose of 340 mg/m² is well tolerated in children. In addition, imatinib therapy is effective in inducing a high percent of hematologic, cytogenetic and molecular responses, comparable to adults with CML. (This study was registered at ClinicalTrials.gov under identifier NCT00030394.).

Varicella-zoster virus disease is more frequent after cord blood than after bone marrow transplantation.

Immune reconstitution may differ following cord blood transplantation (CBT) and bone marrow transplantation (BMT), and this may lead to a difference in varicella zoster virus (VZV) disease rates. One hundred fourteen VZV seropositive children received a CBT (37 patients), or a T-replete BMT (77 patients) at our institution. Patients did not received specific VZV disease prophylaxis. VZV disease was diagnosed by immunofluorescence or culture in 41 (36%) patients. In multivariate analysis, VZV disease was more frequent in older children (relative risk [RR] 1.11 per year; 95% confidence interval [CI], 1.04-1.18; P = .002), and after CBT (RR 2.27; 95% CI, 1.18-4.34; P = .013). The cumulative incidence of VZV disease at 3 years posttransplant was 46% following CBT. VZV disease incidence was 71% in CBT patients over 10 years old at transplant. Visceral dissemination occurred in 7 patients (6 CBT and 1 BMT) (P = .005). VZV disease is thus more frequent and more severe after CBT than after BMT.

IV busulfan dose individualization in children undergoing hematopoietic stem cell transplant: limited sampling strategies.

We currently calculate area under the busulfan concentration time curve (AUC) using 7 plasma busulfan concentrations (AUC7) drawn after the first of 16 i.v. busulfan doses given as a 2-hour infusion every 6 hours. The aim of this study was to develop and validate limited sampling strategies (LSSs) using 3 or fewer busulfan concentration values with which to reliably calculate AUC in children undergoing hematopoietic stem cell transplant (HSCT). Children in the development group (44) received i.v. busulfan at Sick Kids; the validation group consisted of 35 children who received care at CHU Ste-Justine. Busulfan doses given and subsequent plasma busulfan concentrations were recorded. LSSs using 1 to 3 concentration-time points were developed using multiple linear regression. LSS were considered to be acceptable when adjusted r(2) > 0.9, mean bias <15% and precision <15%. Extent of agreement between the AUC7 values and the LSS AUC was assessed by the intraclass correlation coefficient (ICC) and Bland-Altman (BA) analysis. Agreement was considered to be excellent when the lower limit of the 95% confidence limit of the ICC exceeded 0.9 and when the limits of agreement in the BA analysis were +/-15% for both AUC and dose. Administration of the theoretic adjusted busulfan doses based on each LSS was simulated and cases where the resulting AUC was >1500 or <900 microM x min were noted. LSSs using 1, 2, or 3 plasma busulfan concentrations were developed that showed excellent agreement with AUC7 and adjusted busulfan doses. In the validation sample, only the 2- and 3-point LSSs demonstrated acceptable precision and lack of bias. LSSs using 2 or 3 plasma busulfan concentrations can be used to reliably estimate busulfan AUC after IV administration in children undergoing HSCT.

Transplantation of umbilical-cord blood in babies with infantile Krabbe's disease.

BACKGROUND: Infantile Krabbe's disease produces progressive neurologic deterioration and death in early childhood. We hypothesized that transplantation of umbilical-cord blood from unrelated donors before the development of symptoms would favorably alter the natural history of the disease among newborns in whom the disease was diagnosed because of a family history. We compared the outcomes among these newborns with the outcomes among infants who underwent transplantation after the development of symptoms and with the outcomes in an untreated cohort of affected children. METHODS: Eleven asymptomatic newborns (age range, 12 to 44 days) and 14 symptomatic infants (age range, 142 to 352 days) with infantile Krabbe's disease underwent transplantation of umbilical-cord blood from unrelated donors after myeloablative chemotherapy. Engraftment, survival, and neurodevelopmental function were evaluated longitudinally for four months to six years. RESULTS: The rates of donor-cell engraftment and survival were 100 percent and 100 percent, respectively, among the asymptomatic newborns (median follow-up, 3.0 years) and 100 percent and 43 percent, respectively, among the symptomatic infants (median follow-up, 3.4 years). Surviving patients showed durable engraftment of donor-derived hematopoietic cells with restoration of normal blood galactocerebrosidase levels. Infants who underwent transplantation before the development of symptoms showed progressive central myelination and continued gains in developmental skills, and most had age-appropriate cognitive function and receptive language skills, but a few had mild-to-moderate delays in expressive language and mild-to-severe delays in gross motor function. Children who underwent transplantation after the onset of symptoms had minimal neurologic improvement. CONCLUSIONS: Transplantation of umbilical-cord blood from unrelated donors in newborns with infantile Krabbe's disease favorably altered the natural history of the disease. Transplantation in babies after symptoms had developed did not result in substantive neurologic improvement.

Fatal disseminated Trichosporon asahii infection in a child with acute lymphoblastic leukemia.

Few cases of Trichosporon species infection have been reported in children. The present report describes a case of fatal disseminated Trichosporon asahii infection in a child treated for relapsed leukemia. Voriconazole has previously shown promising activity in vitro, and has been used successfully in the treatment of T asahii infections. The patient died five days after voriconazole treatment was started, and the autopsy revealed widespread systemic dissemination to all organs.

GSTA1 diplotypes affect busulfan clearance and toxicity in children undergoing allogeneic hematopoietic stem cell transplantation: a multicenter study.

Busulfan (BU) dose adjustment following therapeutic drug monitoring contributes to better outcome of hematopoietic stem cell transplantation (HSCT). Further improvement could be achieved through genotype-guided BU dose adjustments. To investigate this aspect, polymorphism within glutathione S transferase genes were assessed. Particularly, promoter haplotypes of the glutathione S transferase A1 (GSTA1) were evaluated in vitro, with reporter gene assays and clinically, in a pediatric multi-center study (N =138) through association with BU pharmacokinetics (PK) and clinical outcomes. Promoter activity significantly differed between the GSTA1 haplotypes (p<0.001) supporting their importance in capturing PK variability. Four GSTA1 diplotype groups that significantly correlated with clearance (p=0.009) were distinguished. Diplotypes underlying fast and slow metabolizing capacity showed higher and lower BU clearance (ml/min/kg), respectively. GSTA1 diplotypes with slow metabolizing capacity were associated with higher incidence of sinusoidal obstruction syndrome, acute graft versus host disease and combined treatment-related toxicity (p<0.0005). Among other GST genes investigated, GSTP1 313GG correlated with acute graft versus host disease grade 1-4 (p=0.01) and GSTM1 non-null genotype was associated with hemorrhagic cystitis (p=0.003). This study further strengthens the hypothesis that GST diplotypes/genotypes could be incorporated into already existing population pharmacokinetic models for improving first BU dose prediction and HSCT outcomes. (No Clinicaltrials.gov identifier: NCT01257854. Registered 8 December 2010, retrospectively registered).

Hypomethylation and hypermethylation of DNA in Wilms tumors.

We quantitatively analysed hypermethylation at CpG islands in the 5' ends of 12 genes and one non-CpG island 5' region (MTHFR) in 31 Wilms tumors. We also determined their global genomic 5-methylcytosine content. Compared with various normal postnatal tissues, approximately 40-90% of these pediatric kidney cancers were hypermethylated in four of the genes, MCJ, RASSF1A, TNFRSF12 and CALCA as determined by a quantitative bisulfite-based assay (MethyLight). Interestingly, the non-CpG island 5' region of MTHFR was less methylated in most tumors relative to the normal tissues. By chromatographic analysis of DNA digested to deoxynucleosides, about 60% of the Wilms tumors were found to be deficient in their overall levels of DNA methylation. We also analysed expression of the three known functional DNA methyltransferase genes. No relationship was observed between global genomic 5-methylcytosine levels and relative amounts of RNA for DNA methyltransferases DNMT1, DNMT3A, and DNMT3B. Importantly, no association was seen between CpG island hypermethylation and global DNA hypomethylation in these cancers. Therefore, the overall genomic hypomethylation frequently observed in cancers is probably not just a response or a prelude to hypermethylation elsewhere in the genome. This suggests that the DNA hypomethylation contributes independently to oncogenesis or tumor progression.

A DNA repeat, NBL2, is hypermethylated in some cancers but hypomethylated in others.

Hypermethylation at certain CpG-rich promoters and hypomethylation at repeated DNA sequences are very frequently found in cancers. We provide the first report that a DNA sequence (NBL2) can be either extensively hypermethylated or hypomethylated in cancer. Previously, it was shown that NBL2, a complex tandem DNA repeat in the acrocentric chromosomes, is hypomethylated at NotI sites in >70% of neuroblastomas and hepatocellular carcinomas and in cells from ICF syndrome (DNMT3B-deficiency) patients. Unexpectedly, by Southern blot analysis of 18 ovarian carcinomas, 51 Wilms tumors, and various somatic control tissues, we found that >70% of the cancers exhibited large increases in methylation at HhaI sites in NBL2 compared with all the controls. In contrast, 17% of the carcinomas showed major decreases in methylation at HhaI and NotI sites. The intermediate levels of methylation at HhaI sites in somatic controls enabled this discovery of cancer-linked hypermethylation and hypomethylation in NBL2. In a comparison of ovarian epithelial carcinomas, low malignant potential tumors, and cystadenomas, NBL2 hypermethylation at HhaI sites was significantly related to the degree of malignancy, and hypomethylation was seen only in the carcinomas. By RT-PCR, we found NBL2 transcripts at low levels in a few cancers and undetectable in various normal tissues. In the tumors there was no association of NBL2 hypomethylation and transcription, but this may reflect NBL2's lack of identifiable promoter elements and our evidence for run-through transcription from adjacent sequences into NBL2. The propensity of NBL2 sequences to become either hypermethylated or hypomethylated in cancer suggests that these opposite epigenetic changes share an early step during carcinogenesis and that cancer-linked hypermethylation might be spontaneously reversible.

Malignant melanoma in childhood and adolescence: report of 13 cases.

We reviewed all cases of malignant melanoma in children younger than 17 years of age who were evaluated at Sainte Justine Hospital, a tertiary care pediatric center, between 1980 and 2002. The medical records and histologic features of all cases were reviewed. Thirteen cases were identified, 4 boys and 9 girls. Fifty-three percent of patients were prepubescent. None of the patients had a predisposing condition (eg, giant congenital nevi, dysplastic nevus syndrome, or xeroderma pigmentosum). One patient had had chemoradiotherapy previously for an undifferentiated pleuropulmonary malignant tumor (blastoma) and another patient had Down syndrome. The most frequent reason for initial consultation was a recent increase in size of the lesion. Three patients had pyogenic granuloma-like lesions. Eighty-five percent of the observed melanomas were nodular in type. Tumor thickness ranged from 0 to 6 mm with a median and mean thickness of 2.8 and 3.2 mm, respectively. The overall 5-year survival rate was 58.8%. Lack of awareness and delay in diagnosis may lead to a higher incidence of thick and intermediate melanoma in children. Because it appears that the majority of melanomas in childhood and adolescence occur de novo, clinicians should consider this condition in the differential diagnosis of any suspect lesion in children and adolescents even without an identified predisposing factor.

Clonal evolution in marrows of patients with Shwachman-Diamond syndrome: a prospective 5-year follow-up study.

OBJECTIVES: Shwachman-Diamond syndrome (SDS) is characterized by varying degrees of marrow failure. Retrospective studies suggested a high propensity for malignant myeloid transformation into myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). The study's aims were to determine the cellular and molecular characteristics as well as the clinical course of malignant myeloid transformation and clonal marrow disease in patients with SDS. METHODS: This is a longitudinal prospective study of 14 patients recruited for annual hematological evaluations. Results of baseline and serial hematological assessments for up to 5 years are reported. RESULTS: Clonal marrow cytogenetic abnormalities (CMCA) were detected in 4 patients (29%) on first testing or at follow-up. The abnormalities were del(20q) in two patients, i(7q) in one, and combined del(20q) and i(7q) in one. The following tests did not distinguish patients with CMCA from other SDS patients: severity of peripheral cytopenia, fetal hemoglobin levels, percentage of marrow CD34+ cells, colony growth from marrow CD34+ cells, cluster-to-colony ratio, marrow stromal function, percentage of marrow apoptosis cells, and granulocyte colony-stimulating factor receptor expression. RAS and p53 mutation analysis and AML blast colony assays were uniformly negative. No patients showed progression into more advanced stages of MDS or into AML. In one patient, the abnormal clone became undetectable after 2 years of follow-up. CONCLUSIONS: We conclude that although CMCA in SDS is high, progression into advanced stages of MDS or to overt AML may be slow and difficult to predict. Treatment should be cautious since some abnormal clones can regress.

Rearrangement of the MLL gene and a region proximal to the RARalpha gene in a case of acute myelocytic leukemia M5 with a t(11;17)(q23;q21).

A case of acute myelocytic leukemia (AML) M5 subtype (French-American-British classification), in a 13-year-old girl showed the abnormal karyotype 46,XX,t(11;17)(q23;q21) in all bone marrow cells analyzed. Rearrangements involving 11q23 are frequent in cases of AML M5 and often involve the MLL gene. Nevertheless, t(11;17)(q23;q21) is very rare in this type of leukemia. In acute promyelocytic leukemia, the RARalpha gene, located at 17q21, is involved in almost all cases. Fluorescence in situ hybridization studies revealed a deletion of the C-terminal part of the MLL gene and a translocation of the RARalpha gene on the derivative chromosome 11, proximal to the remaining part of the MLL gene. However, hybridization with the LSI RARA dual color break-apart rearrangement probe showed that the RARalpha gene was not rearranged in this translocation. This is the first study reporting a t(11;17)(q23;q21) with a deletion distal to MLL gene exon 6 in a case of AML M5. Furthermore, this is the second study that strongly suggests the implication of a gene proximal and close to the RARalpha locus in a case of AML M5. According to these results, the discovery of new fusion partner genes of MLL and the precise characterization of t(11;17) will be important for the understanding of neoplastic cell differentiation in AML M5.

Satellite DNA hypomethylation in karyotyped Wilms tumors.

Previously, a high percentage of Wilms tumors was found to be hypomethylated in the unusually long region of pericentromeric satellite DNA on chromosome 1. We now show that these pediatric cancers are also frequently hypomethylated in centromeric satellite DNA throughout the genome and compare satellite DNA hypomethylation with chromosome rearrangements. Relative to normal somatic tissues, 83% of the tumors were hypomethylated in centromeric satellite alpha DNA. This was assessed by blot hybridization under low-stringency conditions after digestion with CpG methylation-sensitive restriction endonucleases. Similar results were obtained with different enzymes, indicating generalized hypomethylation of centromeric DNA. Hypomethylation of another heterochromatic sequence, juxtacentromeric satellite 2 DNA of chromosome 1, was observed in 51% of the tumors. By cytogenetic analysis, rearrangements in the centromeric or juxtacentromeric heterochromatin of chromosome 1 were the most frequent structural aberration and were seen in 14% of the tumors. Tumors with such rearrangements had hypomethylation of satellite DNA in the pericentromeric region. These results show a high degree of targeting of DNA hypomethylation to centromeric and juxtacentromeric satellite DNA sequences in cancer and are consistent with satellite DNA hypomethylation contributing to, but not sufficing for, karyotypic instability in cancer and possibly playing other roles in carcinogenesis.