Abstract 2422: The trimeric engineered fusion protein with CD154 peptide mimetic (OmpC-CD154p), induced apoptotic signaling in B-NHL cell lines mediated by caspase 3 and caspase 8 activation

Abstract

Abstract CD154 (CD40-ligand) is a critical transmembrane molecule with potent immune-stimulatory properties and is clinical applied in gene therapy for leukemia and lymphoma. The interaction between CD40, a member of the tumor necrosis factor superfamily, and its ligand CD154 is essential for the development of humoral and cellular immune responses. Selective inhibition or activation of this pathway forms the basis for the development of new therapeutics against immunologically-based diseases and malignancies. Engagement of CD40-CD154 induces activation and proliferation of B lymphocytes and triggers apoptosis of carcinoma and B lymphoma cells. Several clinical trials have been reported targeting CD40 in cancer patients using recombinant CD154, mAbs and gene therapy, which were well tolerated and resulted in objective tumor responses. In addition to these therapies, CD154 mimetics have been considered with the objective to augment and potentiate the direct cytotoxic anti-tumor activity and for better accessibility to tumor sites. This approach was developed by us and we hypothesized that the genetic engineering of a fusion protein containing a CD154 peptide mimetic additional to be trimeric may be advantageous in that it may have a better affinity to CD40 on B cell malignancies and trigger cell death. The fusion partner may be a carrier targeting other surface molecules expressed on the malignant cells. This hypothesis was tested by the development of a gene fusion of Salmonella typhi OmpC protein expressing the CD154 Trp140-Ser149 amino acid strand. This OmpC-CD154p fusion protein binds CD40 and triggers the CD40 expressing B cells. In this study, we demonstrate that OmpC-CD154p treatment inhibits cell growth and proliferation, on B-NHL cell lines Raji and Ramos. In addition, significant apoptosis was achieved and the extent of apoptosis was a function of the concentration used and time of incubation. The anti-tumor effect was specific as treatment with OmpC alone had no effect. OmpC-CD154p treatment induced activation of caspase 3 active and caspase 8. These findings establish the basis for the development of new fusion proteins specificity targeting the tumor cells directly and mechanism mediated by extrinsic pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2422.