Microarray Gene Expression Analysis to Evaluate Cell Type Specific Expression of Targets Relevant for Immunotherapy of Hematological Malignancies.

Cellular immunotherapy has proven to be effective in the treatment of hematological cancers by donor lymphocyte infusion after allogeneic hematopoietic stem cell transplantation and more recently by targeted therapy with chimeric antigen or T-cell receptor-engineered T cells. However, dependent on the tissue distribution of the antigens that are targeted, anti-tumor responses can be accompanied by undesired side effects. Therefore, detailed tissue distribution analysis is essential to estimate potential efficacy and toxicity of candidate targets for immunotherapy of hematological malignancies. We performed microarray gene expression analysis of hematological malignancies of different origins, healthy hematopoietic cells and various non-hematopoietic cell types from organs that are often targeted in detrimental immune responses after allogeneic stem cell transplantation leading to graft-versus-host disease. Non-hematopoietic cells were also cultured in the presence of IFN-γ to analyze gene expression under inflammatory circumstances. Gene expression was investigated by Illumina HT12.0 microarrays and quality control analysis was performed to confirm the cell-type origin and exclude contamination of non-hematopoietic cell samples with peripheral blood cells. Microarray data were validated by quantitative RT-PCR showing strong correlations between both platforms. Detailed gene expression profiles were generated for various minor histocompatibility antigens and B-cell surface antigens to illustrate the value of the microarray dataset to estimate efficacy and toxicity of candidate targets for immunotherapy. In conclusion, our microarray database provides a relevant platform to analyze and select candidate antigens with hematopoietic (lineage)-restricted expression as potential targets for immunotherapy of hematological cancers.

The genetic basis of uveal melanoma.

Uveal melanoma (UM) is the most common intraocular malignancy in adults with an incidence of about 1/100,000 new cases per year in the Western world. Risk factors are having a light skin, blond hair and blue eyes. As some UM patients have a young age at diagnosis or an affected family history for UM or other malignancies, there may be an underlying genetic basis. This review discusses known or suspected risk factors for UM, the cancer risk in UM patients and their family members, and the genes that have been reported to predispose to UM (germline mutations) and tumor development (somatic mutations).

Despite differential gene expression profiles pediatric MDS derived mesenchymal stromal cells display functionality in vitro.

Pediatric myelodysplastic syndrome (MDS) is a heterogeneous disease covering a spectrum ranging from aplasia (RCC) to myeloproliferation (RAEB(t)). In adult-type MDS there is increasing evidence for abnormal function of the bone-marrow microenvironment. Here, we extensively studied the mesenchymal stromal cells (MSCs) derived from children with MDS. MSCs were expanded from the bone-marrow of 17 MDS patients (RCC: n=10 and advanced MDS: n=7) and pediatric controls (n=10). No differences were observed with respect to phenotype, differentiation capacity, immunomodulatory capacity or hematopoietic support. mRNA expression analysis by Deep-SAGE revealed increased IL-6 expression in RCC- and RAEB(t)-MDS. RCC-MDS MSC expressed increased levels of DKK3, a protein associated with decreased apoptosis. RAEB(t)-MDS revealed increased CRLF1 and decreased DAPK1 expressions. This pattern has been associated with transformation in hematopoietic malignancies. Genes reported to be differentially expressed in adult MDS-MSC did not differ between MSC of pediatric MDS and controls. An altered mRNA expression profile, associated with cell survival and malignant transformation, of MSC derived from children with MDS strengthens the hypothesis that the micro-environment is of importance in this disease. Our data support the understanding that pediatric and adult MDS are two different diseases. Further evaluation of the pathways involved might reveal additional therapy targets.

No evidence for JAK2(V617F) mutation in monoclonal B cells in 2 patients with polycythaemia vera and concurrent monoclonal B cell disorder.

Occurrence of Philadelphia chromosome-negative myeloproliferative neoplasms (Ph(-) MPN) and lymphoproliferative disorders, like B cell chronic lymphocytic leukaemia (B-CLL), in the same patient is rare. JAK2(V617F) mutation was recently introduced as a powerful diagnostic tool for Ph(-) MPN. JAK2(V617F) mutation is not present in B-CLL. In 4 previously reported patients with JAK2(V617F)-positive Ph(-) MPN and B-CLL there was no definitive proof of JAK2(V617F) mutation in B-CLL cells, although this was suggested in 1 patient. We present 2 patients with JAK2(V617F)-positive polycythaemia vera who subsequently developed a monoclonal B cell disorder. The granulocytes were separated from the mononuclear cells by centrifugation on density gradient. Using an ARIA-SORP sorter, the CD20+/CD5+ B cells were separated from the CD20+/CD5- B cells, T cells, NK cells and monocytes. On each of the fractions JAK2(V617F) mutation was analysed by allele-specific competitive blocker-PCR. In both patients JAK2(V617F) mutation was present in granulocytes confirming the clinical diagnosis of polycythaemia vera. We did not detect the JAK2(V617F) mutation in the CD20+/CD5+ B cells but detected it in CD20+/CD5- B cells, T and NK cells, indicating a lymphoid subdifferentiation of the JAK2(V617F) MPN clonality. JAK2(V617F) MPN and monoclonal B cell disorder can coexist but there is no evidence that the proliferative behaviour of these B cells is mediated through the JAK2(V617F) mutation.

BFM-oriented treatment for children with acute lymphoblastic leukemia without cranial irradiation and treatment reduction for standard risk patients: results of DCLSG protocol ALL-8 (1991-1996).

Modern treatment strategies, consisting of intensive chemotherapy and cranial irradiation, have remarkably improved the prognosis for children with acute lymphoblastic leukemia. However, patients with a potential for cure are at risk of severe acute and late adverse effects of treatment. Furthermore, in 25-30% of patients treatment still fails. The objectives of the DCLSG study ALL 8 were to decrease the toxicity and to increase the effectivity of BFM-oriented treatment. Decrease of toxicity was aimed at by confirmation of the results of the previous DCLSG study ALL-7, showing that the majority (94%) of children with ALL can successfully be treated with BFM-oriented therapy without cranial irradiation, and by reduction of treatment for standard risk (SRG) patients. To increase the cure rate in medium risk (MRG) patients the efficacy of high doses of intravenous 6-mercaptopurine (HD-6MP) during protocol M and in SRG patients the efficacy of high doses of L-asparaginase (HD-L-ASP) during maintenance treatment was studied in randomized studies. Patient stratification and treatment were identical to protocol ALL-BFM90, with the following differences: no prophylactic cranial irradiation, SRG patients received only phase 1 of protocol I. Four hundred and sixty-seven patients entered the protocol: 170 SRG, 241 MRG and 56 HRG patients. The 5 years event-free survival rate for all patients was 73% (s.e. 2%); for SRG, MRG and HRG patients 85% (s.e. 3%), 73% (s.e. 3%) and 39% (s.e. 7%), respectively. In patients >1 year of age at diagnosis unfavorable prognostic factors were male sex, >25% blasts in the bone marrow at day 15 and initial white blood cell count (WBC) >50 x 10(9)/l. The cumulative risk of CNS relapse rate was 5% (s.e. 1%) at 5 years. These results confirm that the omission of cranial irradiation in BFM-oriented treatment does not jeopardize the overall good treatment results, nor does early reduction of chemotherapy in SRG patients. No benefit was observed from treatment intensification with HD-L-ASP in SRG patients, nor from HD-6MP in MRG patients.

t(7;12)(q36;p13) and t(7;12)(q32;p13)--translocations involving ETV6 in children 18 months of age or younger with myeloid disorders.

Our retrospective karyotype review revealed two rare recurrent translocations affecting ETV6 (TEL): t(7;12)(q36;p13) and t(7;12)(q32;p13). Five patients with a t(7;12) were from a group of 125 successfully karyotyped pediatric patients enrolled in consecutive clinical AML trials of the Dutch Childhood Leukemia Study Group over a period of 7 years. During a search of available cytogenetic databases, we found 7q and 12p abnormalities in two additional Dutch patients and in three participants in Pediatric Oncology Group trials. A del(12p) had been initially identified in four of these patients and re-examination of the original karyograms revealed a t(7;12)(q36;p13) in two instances and a probable t(7;12) in the other two. FISH confirmed the presence of a t(7;12)(q36;p13) in the latter. Most (n = 7) also had trisomy 19. The t(7;12)(q36;p13) (n = 9) was more common than the t(7;12)(q32;p13) (n = 1). These subtle translocations were found only in children 18 months of age or younger. A literature search revealed that the t(7;12) with break-points at 7q31-q36 and 12p12-p13 had been reported in six children with myeloid disorders and in two with acute lymphoblastic leukemia; all were 12 months of age or younger. Only two of the 17 for whom survival data were available, were alive after at least 22 months of continuous complete remission. Our findings suggest that ETV6 rearrangements due to a t(7;12) may play an adverse role in myeloid disorders in children 18 months of age or younger. Therefore, children in this age group with myeloid disorders should be screened for both MLL and ETV6 rearrangements.

Acute leukemias of different lineages have similar MLL gene fusions encoding related chimeric proteins resulting from chromosomal translocation.

The MLL gene, on human chromosome 11q23, undergoes chromosomal translocation in acute leukemias, resulting in gene fusion with AF4 (chromosome 4) and ENL (chromosome 19). We report here translocation of MLL with nine different chromosomes and two paracentric chromosome 11 deletions in early B cell, B- or T-cell lineage, or nonlymphocytic acute leukemias. The mRNA translocation junction from 22 t(4;11) patients, including six adult leukemias, and nine t(11;19) tumors reveals a remarkable conservation of breakpoints within MLL, AF4, or ENL genes, irrespective of tumor phenotype. Typically, the breakpoints are upstream of the zinc-finger region of MLL, and deletion of this region can accompany translocation, supporting the der(11) chromosome as the important component in leukemogenesis. Partial sequence of a fusion between MLL and the AFX1 gene from chromosome X shows the latter to be rich in Ser/Pro codons, like the ENL mRNA. These data suggest that the heterogeneous 11q23 abnormalities might cause attachment of Ser/Pro-rich segments to the NH2 terminus of MLL, lacking the zinc-finger region, and that translocations occur in early hematopoietic cells, before commitment to distinct lineages.

Expression of the nuclear oncogene p53 in colon tumours.

The nuclear tumour antigen p53 is expressed by a gene localized on the p-arm of human chromosome 17, a region frequently deleted in colon carcinomas. Using a monoclonal antibody to p53 antigen, immunohistochemical analysis of carcinomas and dysplastic tubular adenomas of the colon has been performed to study the relation between p53 expression and dysplasia or malignancy. With this methods p53 was detectable in 55 per cent of colon carcinomas (n = 29). In 8 per cent of adenomas (n = 74), focal nuclear p53 expression was found in dysplastic epithelial cells. In general, these p53-positive regions of the polyps were histologically indistinguishable from the neighbouring tubuli. Sometimes the p53-positive nuclei were found in a focus of more highly dysplastic epithelium. The results suggest that expression of the p53 gene may be part of the process of malignant transformation of dysplastic colon polyps.