G17DT is a conjugate of an epitope derived from gastrin 17 linked to Diphtheria toxoid (DT). Gastrin is an autocrine growth factor in pancreatic and other GI tract cancers. In a phase II study of G17DT for advanced pancreatic cancer only 6/13 (45%) formed antibody to 100mcg of G17DT however 15/18 (83%) formed antibody to the higher dose of 250mcg. The median survival of the whole group was 7 months. Side effects were limited to mild local pain and erythema with 3 patients forming an abscess. Patients with pancreatic cancer are thought to have a suppressed immune response compared to other GI cancers.

Aim: To assess anti-DT antibody level pre and post vaccination to determine its correlation with Gastrin antibodies and relationship with immunogen side effects.

Methods: 26 of the 31 vaccinated patients had serum available. 18 had developed antibody to gastrin (G+) and 8 had not (G-). Anti-DT antibody level was determined by in-vitro tissue culture neutralisation of purified DT.

Results: 16 (88%) of the G+ group had non-protective levels of anti-DT antibody before vaccination compared with 7 (87%) of the G- group. In cases given 100mcg of G17DT and …