LUMC Identification of high affinity TCRs directed against B cell malignancy-associated target antigens

Therapeutic reactivity of antibody-mediated immunotherapy and chimeric antigen receptor (CAR) engineered T-cells is based on targeting of extracellular target antigens. Recent clinical studies demonstrate very promising clinical benefit, however these therapies also demonstrate that escape variants, not expressing the targeted antigen, result in relapse of the malignancy. In addition, for many malignancies no tumor-specific membrane associated target antigens are present to be able to specifically target these tumors. Therefore, new immunotherapeutic strategies have to be explored to increase the number of cancer patients that can be treated with adoptive immune therapy. Since T-cell receptors (TCR) are able to recognize antigens derived from both extracellular and intracellular proteins in the context of HLA, the potential target antigen array useful for TCR gene therapy is much broader. However, the widespread application of TCR gene therapy is hampered by lack of tumor-specific TCRs. Negative selection during thymic development deletes T-cells carrying high affinity TCRs for self/tumor-antigens in the context of autologous (self) HLA. In contrast, self-antigens presented in the context of allogeneic (non-self) HLA can elicit strong immune responses as was demonstrated by our group by the isolation of PRAME- and B-cell lineage specific T-cells (Amir et al CCR 2011, Jahn et al Oncotarget 2016). This research proposal focusses on identifying high affinity tumor-specific TCR by exploiting the immunogenicity of foreign HLA molecules combined with an in-house generated HLA -peptide elution library and high throughput T-cell enrichments. Using this strategy a library of potentially useful high affinity TCRs will be selected that exhibit potent anti-tumor reactivity and exert a stringent safety profile.