Gemcitabine versus gemcitabine plus dalteparin thromboprophylaxis in pancreatic cancer

BACKGROUND

Annualised figures show an up to 7-fold higher incidence of vascular thromboembolism (VTE) in patients with advanced pancreatic cancer (APC) compared to other common malignancies. Concurrent VTE has been shown to confer a worse overall prognosis in APC.

METHODS

One hundred and twenty three APC patients were randomised to receive either gemcitabine 1000 mg/m(2) or the same with weight-adjusted dalteparin (WAD) for 12 weeks. Primary end-point was the reduction of all-type VTE during the study period. NCT00462852, ISRCTN: 76464767.

FINDINGS

The incidence of all-type VTE during the WAD treatment period (<100 days from randomisation) was reduced from 23% to 3.4% (p = 0.002), with a risk ratio (RR)of 0.145, 95% confidence interval (CI) (0.035-0.612) and an 85% risk reduction. All-type VTE throughout the whole follow-up period was reduced from 28% to 12% (p = 0.039), RR = 0.419, 95% CI (0.187-0.935) and a 58% risk reduction. Lethal VTE <100 days was seen only in the control arm, 8.3% compared to 0% (p = 0.057), RR = 0.092, 95% CI (0.005-1.635).

INTERPRETATION

Weight adjusted dalteparin used as primary prophylaxis for 12 weeks is safe and produces a highly significant reduction of all-type VTE during the prophylaxis period. The benefit is maintained after dalteparin withdrawal although decreases with time.

Vascular endothelial growth factor polymorphisms and clinical outcome in colorectal cancer patients treated with irinotecan-based chemotherapy and bevacizumab

The aim of the study was to evaluate the association of vascular endothelial growth factor (VEGF) genotypes with treatment efficacy in a randomized trial. This study compared two chemotherapy regimens (FOLFIRI versus XELIRI) combined with bevacizumab, as first-line treatment for metastatic colorectal cancer. DNA was extracted from blood samples of 173 patients participating in the trial. Genotyping was performed for selected SNPs (VEGF-1154, +936, -634, -2578 and -1498). All candidate genotypes were evaluated for associations with overall survival (OS), progression-free survival (PFS) and response rate (RR). There were no significant differences with respect to the distribution of genotypes in the treatment groups. The VEGF-1154 GG genotype was more frequent in patients not responding to treatment compared with responders (65.5 versus 39.8%, P = 0.032). Furthermore, the VEGF-1154 GG genotype was associated with inferior median OS compared with GA (hazards ratio = 1.68; 95% confidence interval: 1.10-2.57; P = 0.016) or with the alternative genotypes (GA and AA) combined (hazards ratio = 1.62; 95% confidence interval: 1.09-2.40; P = 0.017). In multivariate analysis, the VEGF-1154 GG genotype remained a significant adverse factor for OS. Our results support the potential predictive ability of VEGF genotypes in patients with metastatic colorectal cancer receiving irinotecan-based chemotherapy plus bevacizumab, in terms of RR and OS. However, current results should be validated prospectively, in larger cohorts.

Chemoanticoagulation versus chemotherapy in advanced pancreatic cancer (APC): Results of the interim analysis of the FRAGEM trial

4583

Background: Randomised phase III studies in APC, reveal that many patients (pts) (∼20–25%) die within 3 months from randomisation [(Early Death Burden) (EDB)]. More compared to studies done in other cancers despite pts entered on similar ‘global’ clinical criteria (e.g. 7% in colorectal cancer). We hypothesised that EDB in APC is related to hyper-coagulability. Prevention of veno-thromboembolism (VTE) may result in reduction of EDB. To test this we initiated the randomised phase IIb FRAGEM study. Methods: Upon written informed consent pts with inoperable APC, are eligible for the study (MREC N° 07/02/129, UKCRN 1290). Concurrent VTE or anticoagulant therapy are exclusion criteria. Standard arm pts (arm A) receive gemcitabine 1gr/m2 weekly (Burris schedule). Arm B also receives daily dalteparin injections for 12 weeks at therapeutic dose (CLOT schedule). Primary end point is the reduction of VTE, secondary endpoint the reduction of EDB. To detect a reduction of VTE from around 25% to 5% (odds ratio of 0.158), using a two-group chi-squared test with a two-sided 5% significance level and 80% power, a minimum of 59 pts per treatment group are required. Interim analysis was planned after the first 25 pts entered into arm B to exclude toxicity from dalteparin’s therapeutic, given prophylactically, dose. These results are presented here. Results: 26 pts (50% male, 61% with metastases) in arm A and 25 pts (60% male, 44% with metastases) in arm B have been treated so far. The incidence of VTE in arm A was 31% with 3 pts developing leg deep vein thrombosis (DVT) with pulmonary embolism (PE), 2pts DVT, 1 pt splanchnic vein thrombosis and PE, 1 pt PE without DVT and 1 patient a stroke. No VTE observed in arm B. Haemorrhagic events were 7.5% and 4% in arm A and B respectively. Within the first 12 weeks period 4 pts (15%) in arm A died, 2 from PE (autopsy- confirmed in one ‘sudden death’), 1 from stroke and one from progressive cancer. The VTE related mortality was 37%. In arm B the EDB was 4% as 1 pt died from sepsis. Conclusions: Results of the interim analysis indicate that the dose of dalteparin is safe. They also support our hypothesis that reduction of VTE may result in reduction of the EDB. The trial is on course to achieve its primary endpoint.

No significant financial relationships to disclose.

Correlation of MDR 1 expression and CA 125 in ovarian cancer

BACKGROUND

The serum CA 125 marker is elevated in 80% of patients with ovarian adenocarcinoma. MDR 1 gene expression has been identified in a variety of tumor types and its expression has been correlated with multidrug resistance. Whether there is a correlation between CA 125 levels and MDR 1 expression has not been sufficiently investigated. Therefore, the aim of this study was to examine whether an association between serum CA 125 levels and MDR 1 expression exists.

PATIENTS AND METHODS

Serum CA 125 levels were measured during the diagnosis of ovarian cancer. Fresh tumor specimens or ascitic fluid samples were studied for MDR 1 expression by the polymerase chain reaction method (PCR).

RESULTS

Forty patients with ovarian cancer were studied, 34 (85%) of whom had elevated CA 125. Twenty-eight out of the 40 patients were tested for MDR 1 expression; 20 expressed the gene and 8 did not. The median level of CA 125 in specimens expressing the MDR1 gene was 327, and in specimens that did not it was 376. There was no correlation between the CA 125 levels and MDR 1 expression (p = 0.484).

CONCLUSION

There does not seem to be an association between CA 125 levels and expression of the MDR1 gene in patients with ovarian cancer.

Gemcitabine twice weekly as a radiosensitiser for the treatment of brain metastases in patients with carcinoma: a phase I study

Conventional treatment for brain metastases (BM) is whole-brain radiotherapy (WBRT). Efficacy is poor. It might be increased by a potent radiosensitiser such as gemcitabine which is believed to cross the disrupted blood–brain barrier. Primary objective of this study was to determine the maximum tolerated dose (MTD) of twice weekly gemcitabine given concurrently with WBRT. Patients with BM from carcinoma were included. The dose of WBRT was 30 Gys (10 daily fractions). Gemcitabine was given 2–4 h prior to WBRT on days 1 and 8 for the first cohort of patients and then on days 1, 4, 8 and 11. Starting dose was 25 mg m⁻², escalated by 12.5 mg m⁻² increments. At least three patients were included per level. Dose limiting toxicity (DLT) was defined as grade 4 haematological or grade ⩾3 nonhaematological toxicity. A total of 25 patients were included; 74% had a PS 1 (ECOG). In all, 23 had non-small-cell lung cancer, six colorectal, four breast, two renal cell and one oesophageal carcinoma. A total of 92% had concurrent extracranial disease. Six had single BM, 13 had two or three BM and six multiple. Up to 50 mg m⁻² (level 4) no DLT was observed. At 62.5 mg m⁻², one out of six patients developed DLT (thrombocytopenia-bleeding). The next dose level (75 mg m⁻²) was abandoned after grade 4 bone marrow toxicity (fatal neutropenic sepsis) was seen in one out of two patients. So that the dose of 50 mg m⁻² will be taken forward for further study.

Prolonged administration of weekly paclitaxel and trastuzumab in patients with advanced breast cancer

PURPOSE

To evaluate the efficacy and safety of weekly paclitaxel and trastuzumab in patients with HER2-positive metastatic breast cancer, with trastuzumab administered beyond disease progression.

PATIENTS AND METHODS

Twenty-six women with metastatic breast cancer, that was HER2-positive as determined by immunohistochemistry, were treated with weekly paclitaxel 70 or 90 mg/m2 and trastuzumab (4 mg/kg initial dose followed by 2 mg/kg weekly).

RESULTS

The median duration of treatment was 28 (8-72) weeks for paclitaxel and 59 (14-150) weeks for trastuzumab. Two (8%) patients experienced complete and 14 (54%) partial responses, for an overall response rate of 62%. The median time to disease progression was 11 (2.89-36) months and median survival 34+ months. Grade 3/4 adverse events were alopecia (46%), neurotoxicity (15%), leukopenia (12%) and neutropenia (12%). Infusion-related reactions were mild to moderate. No symptomatic cardiac toxicity was observed. No patient discontinued trastuzumab due to toxicity.

CONCLUSION

Prolonged administration of weekly paclitaxel and trastuzumab is effective and well-tolerated in women with HER2-positive metastatic breast cancer.

The genome sequence of Schizosaccharomyces pombe

We have sequenced and annotated the genome of fission yeast (Schizosaccharomyces pombe), which contains the smallest number of protein-coding genes yet recorded for a eukaryote: 4,824. The centromeres are between 35 and 110 kilobases (kb) and contain related repeats including a highly conserved 1.8-kb element. Regions upstream of genes are longer than in budding yeast (Saccharomyces cerevisiae), possibly reflecting more-extended control regions. Some 43% of the genes contain introns, of which there are 4,730. Fifty genes have significant similarity with human disease genes; half of these are cancer related. We identify highly conserved genes important for eukaryotic cell organization including those required for the cytoskeleton, compartmentation, cell-cycle control, proteolysis, protein phosphorylation and RNA splicing. These genes may have originated with the appearance of eukaryotic life. Few similarly conserved genes that are important for multicellular organization were identified, suggesting that the transition from prokaryotes to eukaryotes required more new genes than did the transition from unicellular to multicellular organization.

The cohesin complex: sequence homologies, interaction networks and shared motifs

BACKGROUND

Cohesin is a macromolecular complex that links sister chromatids together at the metaphase plate during mitosis. The links are formed during DNA replication and destroyed during the metaphase-to-anaphase transition. In budding yeast, the 14S cohesin complex comprises at least two classes of SMC (structural maintenance of chromosomes) proteins - Smc1 and Smc3 - and two SCC (sister-chromatid cohesion) proteins - Scc1 and Scc3. The exact function of these proteins is unknown.

RESULTS

Searches of protein sequence databases have revealed new homologs of cohesin proteins. In mouse, Mmip1 (Mad member interacting protein 1) and Smc3 share 99% sequence identity and are products of the same gene. A phylogenetic tree of SMC homologs reveals five families: Smc1, Smc2, Smc3, Smc4 and an ancestral family that includes the sequences from the Archaea and Eubacteria. This ancestral family also includes sequences from eukaryotes. A cohesion interaction network, comprising 17 proteins, has been constructed using two proteomic databases. Genes encoding six proteins in the cohesion network share a common upstream region that includes the MluI cell-cycle box (MCB) element. Pairs of the proteins in this network share common sequence motifs that could represent common structural features such as binding sites. Scc2 shares a motif with Chk1 (kinase checkpoint protein), that comprises part of the serine/threonine protein kinase motif, including the active-site residue.

CONCLUSIONS

We have combined genomic and proteomic data into a comprehensive network of information to reach a better understanding of the function of the cohesin complex. We have identified new SMC homologs, created a new SMC phylogeny and identified shared DNA and protein motifs. The potential for Scc2 to function as a kinase - a hypothesis that needs to be verified experimentally - could provide further evidence for the regulation of sister-chromatid cohesion by phosphorylation mechanisms, which are currently poorly understood.

Human DNA repair genes

Cellular DNA is subjected to continual attack, both by reactive species inside cells and by environmental agents. Toxic and mutagenic consequences are minimized by distinct pathways of repair, and 130 known human DNA repair genes are described here. Notable features presently include four enzymes that can remove uracil from DNA, seven recombination genes related to RAD51, and many recently discovered DNA polymerases that bypass damage, but only one system to remove the main DNA lesions induced by ultraviolet light. More human DNA repair genes will be found by comparison with model organisms and as common folds in three-dimensional protein structures are determined. Modulation of DNA repair should lead to clinical applications including improvement of radiotherapy and treatment with anticancer drugs and an advanced understanding of the cellular aging process.

Molecular characterization of a human DNA kinase

Human polydeoxyribonucleotide kinase is an enzyme that has the capacity to phosphorylate DNA at 5'-hydroxyl termini and dephosphorylate 3'-phosphate termini and, therefore, can be considered a putative DNA repair enzyme. The enzyme was purified from HeLa cells. Amino acid sequence was obtained for several tryptic fragments by mass spectrometry. The sequences were matched through the dbEST data base with an incomplete human cDNA clone, which was used as a probe to retrieve the 5'-end of the cDNA sequence from a separate cDNA library. The complete cDNA, which codes for a 521-amino acid protein (57.1 kDa), was expressed in Escherichia coli, and the recombinant protein was shown to possess the kinase and phosphatase activities. Comparison with other sequenced proteins identified a P-loop motif, indicative of an ATP-binding domain, and a second motif associated with several different phosphatases. There is reasonable sequence similarity to putative open reading frames in the genomes of Caenorhabditis elegans and Schizosaccharomyces pombe, but similarity to bacteriophage T4 polynucleotide kinase is limited to the kinase and phosphatase domains noted above. Northern hybridization revealed a major transcript of approximately 2.3 kilobases and a minor transcript of approximately 7 kilobases. Pancreas, heart, and kidney appear to have higher levels of mRNA than brain, lung, or liver. Confocal microscopy of human A549 cells indicated that the kinase resides predominantly in the nucleus. The gene encoding the enzyme was mapped to chromosome band 19q13.4.

A human DNA editing enzyme homologous to the Escherichia coli DnaQ/MutD protein

Mammalian DNA polymerases alpha and beta lack 3' exonuclease activity and are unable to edit errors after DNA synthesis. However, editing exonucleases can be functions of separate polypeptides. We isolated a widely distributed DNA-specific 3' exonuclease from rabbit liver nuclei, sequenced tryptic peptides by mass spectrometry, and identified the corresponding human open reading frame. The protein expressed from the cloned human sequence exhibits 3' exonuclease activity. The human clone shares sequence homology with the editing function of the Escherichia coli DNA polymerase III holoenzyme, i.e., the DnaQ/MutD protein, and weakly with the editing 3' exonuclease domain of eukaryotic DNA polymerase epsilon. The gene maps to human chromosome 3p21.2-21.3. In a reconstituted human DNA repair system containing DNA polymerase beta and DNA ligase III-XRCC1, accurate rejoining of a 3' mismatched base residue at a single-strand break is dependent on addition of the exonuclease.

Cloning, mapping and expression of UBL3, a novel ubiquitin-like gene

A novel Drosophila melanogaster gene UBL3 was characterized and shown to be highly conserved in man and Caenorhabditis elegans (C. elegans). The human and mouse homologues were cloned and sequenced. UBL3 is a ubiquitin-like protein of unknown function with no conserved homologues in yeast. Mapping of the human and mouse UBL3 genes places them within a region of shared gene order between human and mouse chromosomes on human chromosome 13q12-13 and telomeric mouse chromosome 5 (MMU5).

Genomic analysis of the Tapasin gene, located close to the TAP loci in the MHC

The Tapasin molecule is a member of the immunoglobulin (Ig) superfamily required for the association of TAP transporters and MHC class I heterodimers in the endoplasmic reticulum. In this study, the Tapasin gene was precisely mapped in relation to the MHC. The gene was centromeric of the HLA-DP locus between the HSET and HKE1.5 genes and within 500 kbp of the TAP1 and TAP2 genes. A homologous mouse EST was mapped to a syntenic position on chromosome 17, centromeric of the H-2 K locus. Similarly, the rat Tapasin gene was shown to be in an equivalent location with respect to the RT1.A locus. The localization of Tapasin, TAP, LMP and class I genes within such a short distance of each other on the chromosome implies some regulatory or functional significance. We determined the Tapasin gene sequence for comparison of its structure to that of other Ig superfamily members, such as MHC class I genes. The IgC domain was encoded by a separate exon. However, the positions of the other introns were not characteristic of other Ig superfamily genes, indicating that Tapasin has a distinct phylogeny.