Investigation of peptomimetics of GD2 antibodies as targeted therapy against human small cell lung cancer in-vitro

13128 Background: GD2 is a well-established target that has been validated for neuroblastoma and small cell lung cancer. The therapeutic and diagnostic use of monoclonal antibodies directed to GD2 in small cell lung cancer is well documented. It has been shown that the binding of GD2 monoclonal antibodies alone can induce growth suppression and cell death of small cell lung cancer cells in-vitro. Our laboratory has developed synthetic small molecule peptomimetics as ligands of GD2. Peptomimetics have favorable in-vivo pharmacological properties compared to antibodies with no immunogenicity, longer half-lives, low toxicity, good tissue penetration, biodistribution and high target selectivity. This study proposed to determine the efficacy of peptomimetics of GD2 antibodies against small cell lung cancer cells in-vitro. Methods: 2 human cell lines were studied. H69 is a classic small cell lung cancer and H82 is a morphological variant small cell lung cancer both of which have been reported in the literature to express GD2. Cell surface expression of ganglioside GD2 was analyzed by flow cytometry (FACScan, BD Biosciences) using GD2 mAB 3F8 and GD2 mAB ME361. Cell proliferation was assessed using standard MTT assays with serum containing medium and cultured for approximately 3 doubling times for each cell line. The cell lines were exposed to increasing doses of GD2 specific peptomimetic to a maximum of 25 uM with controls including serum containing media with and without a GD2 negative peptomimetic and assessed for cell proliferation. Results: GD2 expression was confirmed for both cell lines- H69 and H82 using FACs. Exposure of the GD2 specific peptomimetic clearly caused growth suppression on the range of 35–40% when compared to controls. A dose response relationship was demonstrated with a plateau beyond 10 uM concentrations. Each experiment repeated ≥ 3 occasions. Conclusions: We have shown that attachment of GD2 specific peptomimetics can cause decreased cell proliferation in 2 small cell lung cancer cell lines H69 and H82. We have shown that there is a dose response relationship by which these compounds reduce cell viability. Peptomimetics of GD2 antibodies show promise as a targeted therapy for small cell lung cancer in-vitro and warrant further study. [Table: see text]