The analysis of rare chromosomal translocations in myeloproliferative disorders has highlighted the importance of aberrant tyrosine kinase signaling in the pathogenesis of these diseases. Here we ...have investigated samples from 679 patients and controls for the nonreceptor tyrosine kinase JAK2 V617F mutation. Of the 480 myeloproliferative disorder (MPD) samples, the proportion of positive cases per disease subtype was 30 (20%) of 152 for atypical or unclassified MPD, 2 of 134 (2%) for idiopathic hypereosinophilic syndrome, 58 of 72 (81%) for polycythemia vera, 24 of 59 (41%) essential thrombocythemia (ET), and 15 of 35 (43%) for idiopathic myelofibrosis. V617F was not identified in patients with systemic mastocytosis (n = 28), chronic or acute myeloid leukemia (n = 35), secondary erythrocytosis (n = 4), or healthy controls (n = 160). Homozygosity for V617F was seen in 43% of mutant samples and was closely correlated with chromosome 9p uniparental disomy. Homozygosity was significantly less common in ET compared with other MPD subtypes. In 53 cases analyzed, the median level of PRV1 expression was significantly higher in V617F-positive cases compared with cases without the mutation. We conclude that V617F is widespread in MPDs. Detection of this acquired mutation is likely to have a major impact on the way patients with MPD are diagnosed, as well as serving as an obvious target for signal transduction therapy. (Blood. 2005;106:2162-2168)
The retinoblastoma protein (pRb), p16(INK4A), D-type cyclins, and their partners cyclin-dependent kinase (CDK) 4 and 6 constitute a G(1) regulatory pathway commonly targeted in tumorigenesis. Several ...malignancies show a reciprocal correlation between genetic alterations of single members of the pRb pathway. Therefore, we determined the frequency of Rb deletions and cyclin D1 alterations by fluorescence in situ hybridization as well as 5' CpG island hypermethylation of the p16(INK4A)gene using methylation-specific polymerase chain reaction in bone marrow mononuclear cells from 82 individuals with plasma cell disorders. Alterations in at least one of the components of the pathway were found in 75%. Cyclin D1 translocations or amplifications were detected in 14/82 (17.1%), Rb deletions at 13q14 in 23/82 (28%) of the cases, including three (3.6%) homozygous deletions. p16(INK4A) was hypermethylated in 33/57 (57.9%) of the samples. Further analysis revealed a highly significant correlation between cyclin D1 alterations and extramedullar or leukemic myeloma manifestations (P = 0.014; Fisher's test). Whereas Rb deletions seemed to occur alternatively to cyclin D1 alterations, no reciprocal correlation was found between p16(INK4A) hypermethylations and cyclin D1 or Rb locus aberrations. Cyclin D1 locus alterations and Rb deletions were associated with a significantly worse prognosis whereas p16(INK4A) hypermethylation had no impact on survival. We conclude that cyclin D1 and Rb aberrations seem to occur as alternative events in plasma cell malignancies and contribute to clinical course and prognosis. In contrast, although p16(INK4A) hypermethylation is frequent, inactivation of p16(INK4A) seems not to be involved in the pathogenesis of plasma cell disorders.
Preclinical data suggest that the anti-tumour activity of capecitabine is enhanced by taxanes and mitomycin C through up-regulation of thymidine phosphorylase (TP). Here, we studied safety and ...efficacy of the combination of capecitabine with docetaxel and mitomycin C. Two dose levels (DL) were investigated: capecitabine 1000 mg m(-2) b.i.d. on days 1-14, docetaxel 40 mg m(-2) i.v. day 1, mitomycin C 4 or 6 mg m(-2) i.v. day 1 (DL I or II). Cycles were repeated every 3 weeks. The primary aim was to determine the dose-limiting toxicities (DLT) during the first two treatment cycles and the maximum tolerated dose (MTD). A total of 46 patients (pts) refractory to standard therapies were enrolled, of whom the majority had gastrointestinal tumours (n=40). 14 pts had received >/=3 lines of prior chemotherapy. At DL I, one out of six pts experienced DLT. At DL II, two out of six pts had DLT (mucositis grade 3). Thus, DL I was determined as MTD. Among a total of 37 pts treated on DL I the following toxicities were observed during cycles 1 and 2 (number of patients with grade 1/2/3/4 toxicity; NCI-CTC v. 3.0): anaemia 10/8/3/0, leucocytopenia 4/11/1/2, thrombocytopenia 0/1/2/0, diarrhoea 8/1/2/0, stomatitis/mucositis 3/3/1/0, nausea/vomiting 10/2/0/0, and hand-foot skin reaction 5/1/1/0. Of 30 pts who received at least two treatment cycles nine achieved complete or partial remissions, six pts achieved minor remissions, and seven pts had stable disease (tumour control rate 73%). Of note, four out of 10 patients with pancreatic cancer had partial remissions. In conclusion, capecitabine can safely be combined with docetaxel (40 mg m(-2)) and mitomycin C (4 mg m(-2)). The established regimen was well tolerated and the preliminary efficacy data in this heavily pre-treated patients population appears to be promising.
Invasive aspergillosis (IA) is a life-threatening infection in severely immunocompromised patients, especially those receiving intensive chemotherapy or undergoing haematopoietic stem cell ...transplantation. As the clinical diagnosis of IA is mostly based on biomarkers (galactomannan, β-d-glucan, PCR assays) indicating Aspergillus as the underlying pathogen, the effect of antifungal treatment on the performance of these parameters is still controversial. We evaluated the effect of antifungal treatment on the performance of an Aspergillus-specific PCR assay in bronchoalveolar lavage (BAL) samples.
Two-hundred-and-twenty-six BAL samples from 226 patients with haematological malignancies at high risk for IA classified according to the 2008 European Organization for the Research and Treatment of Cancer criteria were analysed retrospectively for the diagnostic performance of a nested Aspergillus PCR assay in relation to the number and type of mould-active antifungals received prior to BAL sampling.
Sensitivity of BAL PCR for patients without antifungal treatment prior to BAL sampling was 0.69, whereas specificity was 0.87. While no significant change in diagnostic performance by the addition of one antifungal was observed, receiving two or more antifungals prior to BAL sampling led to a significant decrease in the diagnostic performance of BAL PCR testing (P < 0.009).
Treatment with mould-active antifungals prior to BAL sampling significantly decreases the performance of the Aspergillus PCR assay in haematological patients if BAL was performed after administration of more than one antifungal agent. Performing BAL sampling for Aspergillus PCR diagnostic despite pre-treatment with one antifungal or while on prophylaxis is feasible.
Although targeting the BCR-ABL tyrosine kinase activity by imatinib mesylate has rapidly become first-line therapy in chronic myeloid leukemia (CML), drug resistance suggests that combination therapy ...directed to a complementing target may significantly improve treatment results. To identify such potential targets, we used lentivirus-mediated RNA interference (RNAi) as a tool for functional genomics in cell lines as well as primary normal and CML CD34+ cells. In a conditional cell culture model, we demonstrate that RNAi-mediated reduction of SHP2, STAT5, and Gab2 protein expression inhibits BCR-ABL-dependent but not cytokine-dependent proliferation in a dose-dependent manner. Similarly, colony formation of purified primary CML but not of normal CD34+ colony-forming cells is specifically reduced by inhibition of SHP2, STAT5, and Gab2 expression, respectively. In addition, coexpression of both anti-BCR-ABL and anti-SHP2 shRNAs from a single lentiviral vector induces stronger inhibition of colony formation as compared to either shRNA alone. The data indicate that BCR-ABL expression may affect the function of normal signaling molecules. Targeting these molecules may harbor significant therapeutic potential for the treatment of patients with CML.
Imatinib mesylate blocks the activity of three protein tyrosine kinases: ABL, KIT, and platelet-derived growth factor receptor β (PDGFRB). These kinases have crucial roles in chronic myelogenous ...leukemia (ABL), gastrointestinal stromal tumors (KIT), and certain myeloproliferative diseases (PDGFRB). The first two types of neoplasms have been shown to respond to imatinib mesylate. This article reports that in four patients, a myeloproliferative disorder involving a rearranged
PDGFRB
gene also responded to the drug.
The association of leukemia, eosinophilia, and abnormalities of chromosome 12p13 was originally reported by Keene et al. in 1987
1
; two of the four patients included in that report also had translocations involving chromosome 5q3. Subsequently, Golub et al.
2
showed that the previously described t(5;12)(q31–q33;p13) chromosomal abnormality, characteristic of some cases of chronic myelomonocytic leukemia, was associated with a fusion gene linking
TEL
(now known as
ETV6
) with platelet-derived growth factor receptor beta (
PDGFRB
). At least 34 cases of chronic myeloproliferative disease associated with a t(5;12)(q31–q33;p13) translocation have now been reported,
3
and the
PDGFRB
gene is known . . .
Recently, p73, a protein with structural and functional similarities to p53, an extensively studied tumor suppressor gene, has been cloned. After being mapped to the chromosomal region 1p35-1p36, it ...has been postulated to act as a tumor suppressor gene, too, as this region is altered in several human malignancies. Deletions of the short arm of chromosome 1 have frequently been described in multiple myeloma (MM) whereas structural abnormalities of the 17p13 region including p53 are rare events in this disease. Since it has been proposed that especially neoplasias lacking p53 alterations might show a loss of heterozygosity at 1p35-1p36, we studied the frequency of p53 and p73 deletions in bone marrow mononuclear cells of 68 patients with MM, two patients with monoclonal gammopathy of undetermined significance and four patients with plasma cell leukemia. Dual-color fluorescence in situ hybridization (FISH) for p53 and p73 was performed using commercially available DNA probes for 17p13.3 and the microsatellite marker D1Z2, respectively. Centromeric DNA probes served to distinguish gene deletions from whole chromosome losses. In contrast to recently published FISH results, we only detected heterozygous p53 deletions in eight out of the 74 patients, three of them showing a monosomy 17. Heterozygous deletions of the D1Z2 region at 1p36 were found in six cases with one patient having a monosomy 1. Neither homozygous deletions of either chromosomal region nor nullisomies 1 or 17 could be detected. These results argue against a major role of p73 deletions in MM. As MM patients with 1p structural abnormalities have a significantly poorer survival rate than those with normal karyotypes, the role of other putative tumor suppressor genes located at the chromosomal region 1p36 in the pathogenesis of MM has to be determined.
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