Peter Baier

Su1524 Response to Neoadjuvant Therapy and the Lymph Node Ratio (Lnr) are the Strongest Prognostic Factors After Esophageal Resection for Cancer

The exact role of neoadjuvant therapy (neoT) including its prognostic influence in esophageal cancer is still under debate. Pooled data (metaanalysis) suggest a prognostic advantage of neoT but definitve data are lacking. We analyzed our institutional experience with resected esophageal cancer including the effect of neodjuvant therapy on long-term outcome. Methods: We evaluated overall survival in 304 patients undergoing esophageal resection between 1988 and 2010 (patients with hospital mortality excluded). 53% had squamous cell (SCC) and 46% adenocarcinoma (AC). Indications for neoT were in general T-stage >2 and/or positively staged lymph nodes. Tumors were in the lower third in 64%. 66% of the patients underwent neoT (60% chemoradiation 36 Gy+FU+Cisplatin; 6% chemotherapy alone). The proportion of neoT increased from 16% in the first third to 78% in the last third of the study period. In pathological analysis the median number of examined nodes was 17; 43% were node positive. Survival was analyzed by the Kaplan-Meierand Cox-models. Results: The proportion of patients with AC increased from 22% (first third) to 61% (last third of the study period). After neoT 81% of the patients showed partial or total response. Patients without neoT had more frequently positive margins (13% vs 4% after neoT; p 0.1 (p 0.1 (p 0.1 (43% vs 16%). Conclusions: Tumorbiological parameters (histological type, LNratio) influenced prognosis after resection of esophageal cancer. Response to neoadjuvant therapy independently improved the outcome and contributed to the clearly better outcome achieved in the later study period.

Inhibition of transthyretin-met30 expression with inosine15.1-hammerhead ribozymes in cell culture

Hereditary amyloidosis is primarily caused by mutations within the transthyretin gene. More than 75 mutations within transthyretin have been reported in causing amyloidosis. The most common mutation is the val30met mutation in the transthyretin protein (TTR-met30) caused by a mononucleic substitution from G to A (GUC to AUC) in the transthyretin gene resulting in the exchange for the amino acids valine to methionine in the corresponding protein sequence. The aim of this work is the development of a specific cleavage of TTR-met30 mRNA in the cell culture system using hammerhead ribozymes. We showed previously that chemically modified nuclease stable Inosine(15.1)-Hammerhead ribozymes are able to target the TTR-met30 mRNA with high specificity on the RNA level (Biochem. Biophys. Res. Commun. 260, 313-317, 1999). Now we present data confirming our observations on the cellular level. We used the wild-type human normal (hn) TTR expressing cell line HepG2 and the stable transfected cell line 293-TTR-met30 for TTR-met30 experiments. We cleaved the TTR-met30 and hnTTR mRNA with specific nuclease stable chemically modified Inosine(15.1)-Hammerhead ribozymes and analyzed the protein after immunoprecipitation and subsequent Western blotting. We were able to downregulate the TTR concentration by 54.5% (100% = 1.5 mg/l TTR) and also specifically to target the TTR-met30 expression in the cell culture system. The therapeutic effect was improved using cationic liposomes resulting in a total downregulation by 92.1 and 62.7% targeting hnTTR mRNA and TTR-met30 mRNA, respectively. The successful employment of Inosine(15.1)-Hammerhead ribozymes in cell culture is therefore a promising tool for the development of a gene therapeutic strategy for hereditary amyloidosis.