No abstract

Background-Gene therapy offers an unprecedented opportunity to treat diverse pathologies. Adeno-associated virus (AAV) is a promising gene delivery vector for cardiovascular disease. However, AAV transduces the liver after systemic administration, reducing its usefulness for therapies targeted at other sites. Because vascular endothelial cells (ECs) are in contact with the bloodstream and are heterogeneous between organs, they represent an ideal target for site-specific delivery of biological agents. Methods and Results-We isolated human venous EC-targeting peptides by phage display and genetically incorporated them into AAV capsids after amino acid 587. Peptide-modified AAVs transduced venous (but not arterial) ECs in vitro, whereas hepatocyte transduction was significantly lower than with native AAV. Intravenous infusion of engineered AAVs into mice produced reduced vector accumulation in liver measured 1 hour and 28 days after injection and delayed blood clearance rates compared with native AAV. Peptide-modified AAVs produced enhanced uptake of virions in the vena cava with selective transgene expression. Retargeting was dose dependent, and coinfusion of either heparin or free competing peptides indicated that uptake was principally independent of native AAV tropism and mediated via the peptide. Conclusions-AAV tropism can be genetically engineered by use of phage display-derived peptides to generate vectors that are selective for the vasculature.

Both treatments proved to be effective, with no differences in response and survival between the two treatment arms. The EC regimen was associated with significantly less toxicity.

The association of p53 codon 72 polymorphism with cancer has been investigated by several scientific groups with controversial results. In the present study, we examined the genotypic frequency of this polymorphism in 54 patients with advanced lung cancer and 99 normal controls from the geographical region of Greece. Sputum and bronchial washing samples from each patient were assayed for the presence of human papillomavirus. Codon 72 heterozygous (Arg/Pro) patients were also analysed for loss of heterozygosity at the TP53 locus, in order to determine the lost p53 allele (Arg or Pro). p53 Arg/Arg genotype was significantly increased in lung cancer patients compared to normal controls (50% vs 24.2%, P50.002). Human papillomavirus was detected only in two patients (3.7%). Loss of heterozygosity at the TP53 locus was found in 14 out of 27 Arg/Pro patients (51.85%). The Pro allele was lost in 11 cases (78.6%), while the Arg allele was lost in three (21.4%). Our results suggest that p53 codon 72 Arg homozygosity is associated with advanced lung cancer, and that the Arg allele is preferentially retained in patients heterozygous for this polymorphism. On the other hand, human papillomavirus infection does not seem to play an important role in lung carcinogenesis.

In this early terminated study, the TEP regimen was significantly more toxic than the EP regimen. The TEP regimen is associated with significant toxicity and mortality, and should not be used outside of a protocol setting. For future investigations, dose and schedule modifications are necessary to reduce toxicity.