Background: The benefit of neoadjuvant chemoradiotherapy in oesophageal cancer has been extensively studied but data on survival are still equivocal. Objective: To assess the effectiveness of ...chemoradiotherapy followed by surgery in the reduction of mortality in patients with resectable oesophageal cancer. Methods: Computerised bibliographic searches of MEDLINE and CANCERLIT (1970–2002) were supplemented with hand searches of reference lists. Study selection: Studies were included if they were randomised controlled trials (RCTs) comparing preoperative chemoradiotherapy plus surgery with surgery alone, and if they included patients with resectable histologically proven oesophageal cancer without metastatic disease. Six eligible RCTs were identified and included in the meta-analysis. Data extraction: Data on study populations, interventions, and outcomes were extracted from each RCT according to the intention to treat method by three independent observers and combined using the DerSimonian and Laird method. Results: Chemoradiotherapy plus surgery compared with surgery alone significantly reduced the three year mortality rate (odds ratio (OR) 0.53 (95% confidence interval (CI) 0.31–0.93); p = 0.03) (number needed to treat = 10). Pathological examination showed that preoperative chemoradiotherapy downstaged the tumour (that is, less advanced stage at pathological examination at the time of surgery) compared with surgery alone (OR 0.43 (95% CI 0.26–0.72); p = 0.001). The risk for postoperative mortality was higher in the chemoradiotherapy plus surgery group (OR 2.10 (95% CI 1.18–3.73); p = 0.01). Conclusions: In patients with resectable oesophageal cancer, chemoradiotherapy plus surgery significantly reduces three year mortality compared with surgery alone. However, postoperative mortality was significantly increased by neoadjuvant chemoradiotherapy. Further large scale multicentre RCTs may prove useful to substantiate the benefit on overall survival.
To review the available evidence of chemoembolization for unresectable hepatocellular carcinoma (HCC).
Computerized bibliographic searches with MEDLINE and CANCERLIT databases from 1980 through 2000 ...were supplemented with manual searches, with the keywords "hepatocellular carcinoma," "liver cell carcinoma," "randomized controlled trial RCT," and "chemoembolization." Studies were included if patients with unresectable HCC were enrolled and if they were RCTs in which chemoembolization was compared with nonactive treatment (five RCTs) or if different transarterial modalities of therapy (13 RCTs) were compared. Data were extracted from each RCT according to the intention-to-treat method. Five of the RCTs with a nonactive treatment arm were combined by using the random-effects model, whereas all 18 RCTs were pooled from meta-regression analysis.
Chemoembolization significantly reduced the overall 2-year mortality rate (odds ratio, 0.54; 95% CI: 0.33, 0.89; P =.015) compared with nonactive treatment. Analysis of comparative RCTs helped to predict that overall mortality was significantly lower in patients treated with transarterial embolization (TAE) than in those treated with transarterial chemotherapy (odds ratio, 0.72; 95% CI: 0.53, 0.98; P =.039) and that there is no evidence that transarterial chemoembolization is more effective than TAE (odds ratio, 1.007; 95% CI: 0.79, 1.27; P =.95), which suggests that the addition of an anticancer drug did not improve the therapeutic benefit.
In patients with unresectable HCC, chemoembolization significantly improved the overall 2-year survival compared with nonactive treatment, but the magnitude of the benefit is relatively small.
When and how to treat acute hepatitis C? Licata, Anna; Di Bona, Danilo; Schepis, Filippo ...
Journal of hepatology,
12/2003, Letnik:
39, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Background: Appropriate treatment of acute hepatitis C is still a matter of controversy due to the lack of large controlled trials.
Aim: To assess the effectiveness of interferon as treatment for ...acute hepatitis C by meta-analysis.
Methods: MEDLINE search (1985–2002) was supplemented with manual searches of reference lists. Studies were included if they were controlled trials comparing interferon to no treatment and if they included patients with either post-transfusion or sporadic acute hepatitis C. Twelve trials were analyzed (414 patients). The outcome assessed was the sustained virological response (SVR) rate (undetectable hepatitis C virus RNA in serum at least 6 months after cessation of therapy).
Results: Interferon significantly increased the SVR (risk difference 49%; 95% confidence interval 32.9–65%) in comparison to no treatment. The risk difference of SVR increased from 5 to 90% when trials were ordered by increasing interferon weekly dose. Delaying therapy by 8–12 weeks after the onset of disease does not compromise the SVR rate.
Conclusions: Current evidence is sufficient to recommend interferon treatment of patients with acute hepatitis C. A later initiation of therapy yields the same likelihood of response as early treatment. A daily induction dose during the 1st month is the best option of treatment.
Unconjugated monoclonal antibodies have emerged as important therapeutic agents for selected malignancies. One mechanism by which antibodies can exert cytotoxic effects is antibody-dependent cellular ...cytotoxicity (ADCC). In an effort to increase the efficiency of ADCC at tumor sites, we have focused on the construction of bispecific antibodies specific for the tumor antigen HER2/neu and the FcγRIII-activating receptor (CD16) found on NK cells, mononuclear phagocytes, and neutrophils. Here, we describe the production of bispecific minibodies in two distinct binding formats. The parent minibody was constructed such that the IgG1 CH3 constant domain serves as the oligomerization domain and is attached to an anti-CD16 and an anti-HER2/ neu single-chain Fv via 19- and 29-amino acid linkers, respectively. This molecule can be expressed in mammalian cells from a dicistronic vector and has been purified using sequential affinity purification techniques. Analysis by surface plasmon resonance shows that the bispecific minibody can bind to HER2/neu and CD16, both individually and simultaneously. Furthermore, cytotoxicity studies show that the minibody can induce significant tumor cell lysis at a concentration as low as 20 nm. A trimeric, bispecific minibody (TriBi) that binds dimerically to HER2/neu and monomerically to CD16 induces equivalent cytotoxicity at lower antibody concentrations than either the parent minibody or the corresponding single-chain dimer. Both minibody constructs are stable in mouse and human serum for up to 72 h at 37 °C. These minibodies have the potential to target solid tumors and promote tumor lysis by natural killer cells and mononuclear phagocytes.
We tested the hypothesis that bispecific Abs (Bsab) with increased binding affinity for tumor Ags augment retargeted antitumor cytotoxicity. We report that an increase in the affinity of Bsab for the ...HER2/neu Ag correlates with an increase in the ability of the Bsab to promote retargeted cytotoxicity against HER2/neu-positive cell lines. A series of anti-HER2/neu extracellular domain-directed single-chain Fv fragments (scFv), ranging in affinity for HER2/neu from 10(-7) to 10(-11) M, were fused to the phage display-derived NM3E2 human scFV: NM3E2 associates with the extracellular domain of human FcgammaRIII (CD16). The resulting series of Bsab promoted cytotoxicity of SKOV3 human ovarian carcinoma cells overexpressing HER2/neu by human PBMC preparations containing CD16-positive NK cells. The affinity for HER2/neu clearly influenced the ability of the Bsab to promote cytotoxicity of (51)Cr-labeled SKOV3 cells. Lysis was 6.5% with an anti-HER2/neu K(D) = 1.7 x 10(-7) M, 14.5% with K(D) = 5.7 x 10(-9) M, and 21.3% with K(D) = 1.7 x 10(-10) M at 50:1 E:T ratios. These scFv-based Bsab did not cross-link receptors and induce leukocyte calcium mobilization in the absence of tumor cell engagement. Thus, these novel Bsab structures should not induce the dose-limiting cytokine release syndromes that have been observed in clinical trials with intact IgG BSAB: Additional manipulations in Bsab structure that improve selective tumor retention or facilitate the ability of Bsab to selectively cross-link tumor and effector cells at tumor sites should further improve the utility of this therapeutic strategy.
Through the use of various non-equilibrium RNA binding techniques, the C protein tetramer of mammalian 40S hnRNP particles has been characterized previously as a poly(U) binding protein with ...specificity for the pyrimidine-rich sequences that often precede 3′ intron-exon junctions. C protein has also been characterized as a sequence-independent RNA chaperonin that is distributed along nascent transcripts through cooperative binding and as a protein ruler that defines the length of RNA packaged in 40S monoparticles. In this study fluorescence spectroscopy was used to monitor C protein-oligonucleotide binding in a competition binding assay under equilibrium conditions. Twenty nucleotide substrates corresponding to polypyrimidine tracts from IVS1 of the adenovirus-2 major late transcript, the adenovirus-2 oncoprotein E1A 3′ splice site, IVS2 of human α-tropomyosin, the consensus polypyrimidine tract for U2AF65, AUUUA repeats and r(U)20 were used as competitors. A 20 nt β-globin intronic sequence and a randomly generated oligo were used as competitor controls. These studies reveal that native C protein possesses no enhanced affinity for uridine-rich oligonucleotides, but they confirm the enhanced affinity of C protein for an oligonucleotide identified as a high affinity substrate through selection and amplification. Evidence that the affinity of C protein for the winner sequence is due primarily to its unique structure or to a unique context is seen in its retained substrate affinity when contiguous uridines are replaced with contiguous guanosines.
Previous studies have shown that the C protein of 40 S hnRNP complexes contains a leucine-zipper domain, residues 180-207, and that a 40 residue highly basic domain, immediately preceding the zipper, ...is responsible for almost all of the free energy of RNA binding to C protein. Because this domain arrangement is like that seen in the bZIP transcription factors it has been termed the bZIP-like-motif or bZLM. We report here that the zipper domain drives C protein oligomerization through its spontaneous assembly into an anti-parallel four-helix bundle approximately 50 Å in length. The anti-parallel nature of the four-helix bundle positions the tetramer’s four high-affinity RNA binding domains at opposing ends of a rigid core formed by the helix bundle. This domain topology is ideally suited to accommodate and direct a double wrapping of RNA around the tetramer and is fully consistent with C protein’s ability to bind and order 230 nt lengths of pre-mRNA through a highly cooperative RNA binding mode. We have used a novel sequence-specific
13C/
15N labeling strategy and multidimensional NMR spectroscopy to define the anti-parallel orientation of the four-helix bundle and its molecular dimensions.
In vitro reconstitution and hydrodynamic studies on native C protein, on several C protein fragments, and on various synthetic peptides, are consistent with the proposed model and indicate that C protein’s canonical RNA recognition motifs probably function in tetramer-tetramer interactions during 40 S hnRNP assembly.
The hnRNP C protein tetramer cooperatively binds 230 nt increments of pre-mRNA
in vitro in a salt-resistant manner and is located along the length of vertebrate transcripts
in vivo. Based on these ...and other findings it has been suggested that hnRNP C functions as a chaperonin to maintain long lengths of RNA topologically single-stranded and accessible to splicing factors. We report here that human C protein is lethal when expressed in the yeast
Saccharomyces cerevisiae. Through a series of fluorescent immunolocalization studies, lethality was observed to be associated with the rapid nuclear accumulation of both C protein and yeast pre-mRNA. Studies using various protein constructs and the two hybrid assay reveal that these events are dependent on the basic 40 residue high-affinity RNA binding domain and its contiguous leucine zipper-like motif (the bZLM, residues 140-214). Additionally, equilibrium binding studies have shown that the bZLM is the determinant of C protein’s salt-resistant RNA binding mode. Taken together, these findings further distinguish the bZIP-like domain as the major determinant of C protein’s high-affinity interaction with RNA, oligomerization, and its highly cooperative RNA binding activity. Finally, these findings indicate that yeast and vertebrates may possess a conserved mechanism for general import of RNP although a true homolog to vertebrate C protein appears not to exist in yeast. Lethality is likely due to the absence in yeast of specific mechanisms for the removal of human C protein from nascent transcripts.
The C protein tetramer of hnRNP complexes binds approximately 150-230 nt of RNA with high cooperativity (McAfee J et al., 1996, Biochemistry 35:1212-1222). Three contiguously bound tetramers fold ...700-nt lengths of RNA into a 19S triangular intermediate that nucleates 40S hnRNP assembly in vitro (Huang M et al., 1994, Mol Cell Biol 14:518-533). Although it has been assumed that the consensus RNA recognition motif (RRM) of C protein (residues 8-87) is the primary determinant of RNA binding, we report here that a recombinant construct containing residues 1-115 has very low affinity for RNA at physiological ionic strength (100 mM NaCl). Moreover, we demonstrate that an N-terminal deletion construct lacking the consensus RRM but containing residues 140-290 binds RNA with an affinity sufficient to account for the total free energy change observed for the binding of intact protein. Like native C protein, the 140-290 construct is a tetramer in solution and binds RNA stoichiometrically in a salt-resistant manner in 100-300 mM NaCl. Residues 140-179 of the N-terminal truncated variant contain 11 basic and 2 acidic residues, whereas residues 180-207 specify a leucine zipper motif that directs dimer assembly. Elements within the 50-residue carboxy terminus of C protein are required for tetramer assembly. A basic region followed by a leucine zipper is identical to the domain organization of the basic-leucine zipper (bZIP) class of DNA binding proteins. Sequence homologies with other proteins containing RRMs and the bZIP motif suggest that residues 140-207 represent a conserved bZIP-like RNA binding motif (designated bZLM). The steric orientation of four high-affinity RNA binding sites about rigid leucine zipper domains may explain in part C protein's asymmetry, its large occluded site size, and its RNA folding activity.
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