P-70: Development and Assessment of a Recombinant Antibody Against Prostate Stem Cell Antigen (PSCA (Pages: 71-72)

Abdi S *, Nejatollahi F ,


Objective: Pancreatic cancer is a highly lethal neoplasm with poor prognosis however therapeutic and diagnostic approaches available for pancreatic cancer are not efficient. There for introduction of new modalities for treatment and diagnosis of pancreatic cancer is of urgent need. Single-chain fragment variable (scFv) antibodies are one of the most popular recombinant antibodies because of their capacity to be engineered into larger, multivalent, bi-specific and conjugated forms for many clinical applications. PSCA is a surface molecule over expressed in prostate, bladder and pancreatic cancers. Because of limited expression in normal tissues, PSCA has attracted a great amount of interest as an ideal target for immunotherapy. In this study we aimed to develop specific scFv antibodies against PSCA with the purpose of using them as therapeutic and diagnostic tools for pancreatic cancer. Materials and Methods: A library of highly diverse scFvs was panned against an immunodominant epitope of PSCA. PCR was done to evaluate clones carrying the specific band corresponding to the insert. BstN1 fingerprinting of the PCR results revealed the common patterns. Selected clones with the most frequent pattern have been chosen for further investigations. Results: After four rounds of panning, 20 clones were selected randomly. Using PCR process, 16 clones were shown to have the specific band of 950 base pairs represented the insert. Then BstN1 fingerprinting was carried out with the purpose of determining the common patterns. Clones with the most frequent common pattern were selected to further evaluate their binding properties to the pancreatic cancer cell line AsPC-1. Conclusion: Monoclonal antibodies are one of the most powerful and promising tools in therapy and diagnosis of various diseases including cancer. Because of the failure of current therapeutic modalities for curing pancreatic cancer, novel treatment strategies ideally targeting pancreatic cancer cells are needed. Anti-PSCA monoclonal antibody designated 1G8 showed significant anti-tumor efficacy both in vitro and in vivo. In this study we developed a specific scFv antibody against PSCA that can be used as a new therapeutic agent for pancreatic cancer. Further investigations are undergoing in our laboratory to determine the binding ability of the selected scFv to the pancreatic cancer cell line, AsPC-1, and then to evaluate the inhibitory effects of this scFv antibody in vitro.