NCIt definition : An immunotoxin containing an epitope of human gastrin conjugated to diphtheria toxin,
with antineoplastic activity. The gastrin epitope in this vaccine is chemically identical
or similar to the endogenous gastrin-17 (G-17), a 17-amino acid peptide hormone that
stimulates secretion of gastric acid by the stomach. Diphtheria toxin inhibits protein
synthesis via modifying translation elongation factor 2 (EF-2). Vaccination with this
immunotoxin may elicit production of antibodies against gastrinoma cells overexpressing
gastrin, in addition to the toxic effects on protein synthesis exerted by the diphtheria
toxin moiety.;