Survivin: A Potential Target of Adoptive Immunotherapy for Pediatric Sarcomas (101.19)

Abstract

Abstract Cell based immunity is driven by CD8+ cytotoxic T cells bearing TCR that recognize specific tumor-associated peptides bound to class I MHC molecules. Survivin, an inhibitor of apoptosis protein (IAP), is a tumor-associated antigen that is widely expressed in nearly all human cancer cells and undetectable in most normal tissues. Although there is evidence for cytotoxic T cell responses against survivin in patients, tolerance to self antigens can be a limiting factor in generating highly avid T cells capable of killing tumor cells. An alternate approach involves peptide immunization of HLA-A2 transgenic mice that express the human class I HLA-A2 molecule, which could in principle generate more highly avid TCRs to human antigens. In this study, we vaccinated A2 transgenic mice with a modified survivin epitope, Surv96M (LMLGEFLKL) and successfully generated CD8+ CTL clones that react against Survivin96-104 and a human pancreatic cancer line. The α- and β- chains for the TCR of reactive CTLs were cloned and inserted into an retrovirus vector incorporating 2A linker peptides between coding sequences of α- and β- chains of TCRs against survivin. Transduction of survivin specific TCR retrovirus constructs into human PBMCs yielded up to 70% TCR redirected lymphocytes and specific effector function as measured by IFNgamma release following co-culture with peptide-pulsed targets and one A2+ pediatric osteosarcoma line. Ongoing work is underway to increase the TCR affinity to potency.