The use of T-cell receptor (TCR) gene transfer for the treatment of both hematological and solid tumors is increasing. Using TCR gene transfer T cells can be redirected to target tumor or lineage... Show moreThe use of T-cell receptor (TCR) gene transfer for the treatment of both hematological and solid tumors is increasing. Using TCR gene transfer T cells can be redirected to target tumor or lineage-specific antigens. Especially for poor immunogenic tumors this offers the potential to circumvent limitations of the endogenous T-cell repertoire. Still, the broad use of TCR-based therapy is hampered by a limited number of targeted antigens and HLA class I binding restrictions of TCRs. Furthermore, several of the pioneering T-cell based therapies have demonstrated that the balance between therapeutic efficacy and safety remains a challenge as T-cell mediated toxicities have occurred. In this thesis we identified novel targets, peptides and TCRs in order to treat a broader patient population, among others ovarian and prostate cancer patients. We stringently selected appropriate tumor- and lineage-specific targets using a differential gene expression analysis, and identified naturally expressed peptides from the HLA class I associated ligandome. We isolated peptide-specific T cells, sequenced their TCRs and carefully selected the most promising TCRs. Overall, we selected ten TCRs that demonstrated an effective and safe reactivity pattern based on the performed T-cell reactivity screenings. These TCRs demonstrated reactivity against broad panels of patient-derived tumor samples and/or tumor cell lines, without reactivity against a broad variety of healthy cell subsets or other antigen negative cells. Furthermore, in this thesis we set up human induced pluripotent stem cell (hiPSC)-derived models to additionally examine toxicity risks of T cells against vital organs or specialized cell subsets. We demonstrated added value of these models in determining toxicity risks in the preclinical pipeline of TCRs. Show less
Viral infections are agreat risk for successful transplantation. Surprisingly, also the immuneresponse against viruses can affect transplantation outcome, as T cells thatare trained to recognize... Show moreViral infections are agreat risk for successful transplantation. Surprisingly, also the immuneresponse against viruses can affect transplantation outcome, as T cells thatare trained to recognize self-HLA presenting a viral peptide, can make a“mistake” and recognize allogeneic (donor) HLA. This phenomenon is known tooccur frequently, but its clinical relevance remains unknown. In this thesis, we investigated and optimized the methods to detectcross-reactivity of virus-specific T cells in vitro. Illustrating the scope ofthe problem, we found that infection with a single virus induces a broadrepertoire of alloreactive T cells. Conversely, cross-reactivity may also boostanti-viral immunity in immunocompromised patients. Also, we found thatvirus-specific T cells of unrelated individuals can recognize the sameallogeneic HLA much more frequently than anticipated. This knowledge may helpto predict which patient-donor combinations induce alloreactivity.Addressing clinical relevance in transplantation, we showed that the immunepotential against the viral and allogeneic target can be equally strong,depending on the expression of the (allo)epitope. However, clinical relevanceonly truly be determined when the peptides presented by the cross-reactingallo-HLA molecules are identified. A promising allopeptide-defining strategy iscurrently under development at Monash University (Melbourne, Australia),described in the Discussion. Show less
Heuvel, H. van den; Heutinck, K.M.; Meer-Prins, E.M.W. van der; Franke-van Dijk, M.E.I.; Miert, P.P.M.C. van; Zhang, X.Q.; ... ; Claas, F.H.J. 2018
Infusions of T cells engineered with TCRs directed against tumor-expressed antigens have demonstrated clinical efficacy in the treatment of cancer. To broaden the applicability of this... Show moreInfusions of T cells engineered with TCRs directed against tumor-expressed antigens have demonstrated clinical efficacy in the treatment of cancer. To broaden the applicability of this approach a broad repertoire of clinically relevant TCRs is required. This thesis describes a high throughput methodology for the isolation of TCRs useful in the treatment of patients suffering from B-cell malignancies. To induce strong immune responses against tumor-expressed antigens, the immunogencity of allogeneic (non-self) HLA molecules is exploited. Around this fundamental knowledge about T-cell reactivity a pipeline is developed that consists of the selection of targetable tumor-expressed antigens by mining gene expression databases, discovery of HLA-presented peptides from peptide elution studies describing the HLA ligandome of B lymphocytes, a peptide-MHC tetramer based high throughput methodology for the isolation and characterization of T cells expressing TCRs specific for tumor-expressed antigens. Several TCRs were isolated targeting antigens that are expressed on several B-cell malignancies including multiple myeloma. This is of particular interest since novel immunotherapies for multiple myeloma are currently lacking. The work described in this thesis can significantly broaden the applicability of immunotherapy by providing novel tools and reagents for strategies relying on tumor recognition through antigen presentation in the context of HLA. Show less
