Preoperative chemoradiotherapy for oesophageal cancer: a systematic review and meta-analysis.

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.

Increasing the affinity for tumor antigen enhances bispecific antibody cytotoxicity.

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.

An antiparallel four-helix bundle orients the high-affinity RNA binding sites in hnRNP C: a mechanism for RNA chaperonin activity.

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 A 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 bZIP-like motif of hnRNP C directs the nuclear accumulation of pre-mRNA and lethality in yeast.

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.