Project 1: Molecular T-cell Therapy in Allogeneic Hematopoietic Stem-cell Transplantation
Immunotherapy based on the adoptive transfer of ex vivo expanded and activated autologous tumor-reactive lymphocytes can mediate tumor regression in cancer patients. However, high-avidity T cells specific for tumor-associated antigens (TAAs) are usually absent in patients because of self-tolerance. Using HLA-A2.1 transgenic mice, we have demonstrated the feasibility of T-cell receptor (TCR) gene transfer into T cells to circumvent self-tolerance to the widely expressed human p53 and MDM2 TAAs. A safety concern of TCR gene transfer is the risk of pairing between introduced and the naturally expressed endogenous TCR chains, resulting in the generation of self-reactive T cells. To prevent mixed TCR chain dimer formation, we engineered and optimized TAA-specific single chain TCRs. We successfully applied this strategy to the human TAAs p53, gp100 and MDM2-specific TCRs as promising antigen-driven immunotherapy for both, melanoma and hematologic malignancies. Here, we evaluated the safety issues raised by the risk of TAA-TCR gene transfer-associated on/off-target toxicities and the therapeutic potential in relevant transgenic mouse models of adoptive transfer.
Project 2: A novel immune-metabolic anti-tumor strategy: TCR and CAR gene therapy in combination with arginine depletion
This is a joint project together with AG Munder and Prof. Dr. Winfried Wels (Georg-Speyer-Haus, Frankfurt). It aims to improve cancer immunotherapy by combining adoptive innovative cellular therapeutics with targeted inhibition of tumor metabolism by systemic depletion of arginine. We target multiple myeloma (MM) and melanoma tumor cells by T cells redirected with a tumor-associated antigen (MDM2)-specific TCR and a CAR-engineered variant of the human NK cell line NK-92 recognizing the ErbB2/HER2 antigens. Arginine depletion will be induced in vivo by two pharmacologically optimized variants of the enzymes arginine deiminase (ADI) or arginase, which are both in clinical development for various cancer entities. The combination of the T / NK cell-based tumor antigen-specific cellular immuno-therapeutics together with enzymatic Arg depletion will be studied in xenograft mouse tumor models. The potential synergistic effect of the combined immuno-metabolic approach could directly be translated into a clinical treatment protocol, since the Arg-depleting drug ADI-PEG20 is already in phase III clinical trials and ErbB2-specific NK CAR cells are available in GMP format.
[Funding 2016-2017: Deutsches Konsortium für Translationale Krebsforschung (DKTK)]
Project 3: Exploring mutant immunogenic epitopes for T cell therapy of cancer
Together with AG Wölfel we have initiated a multi-center (Mainz, Essen, Heidelberg, Berlin) translational oncology program to explore mutant immunogenic epitopes for T cell therapy of malignant melanoma. Our subproject aims to define tumor-specific antigens (TSAs) by exome and transcriptome sequencing for adoptive T cell therapy (ATT) with TSA-specific T cell receptor (TCR)-transgenic T cells. Melanoma from HLA-A*02:01(A2.1) patient will be analyzed for somatic mutations and their potency to encode TSA peptides presented by A2.1. Candidate peptides will be screened for their recognition by autologous T cells. A2.1-transgenic mice will be immunized with selected peptides to generate TSA-reactive CD8+ T cells. TSA-specific TCRs will be cloned and their functional activity will be analyzed in vitro and in vivo in tumor-transplanted xenograft models. We will also determine the presence of TSA-specific T cells in peripheral blood and tumor samples sequentially collected from candidate patients and the heterogeneity of TSA expression in distinct tumor lesions. Overall, our project will demonstrate how exome and transcriptome data can be exploited to define TSAs and to generate TSA-specific TCR T cells for personalized ATT of cancer patients.
[Funding 2015-2017: Deutsches Krebshilfe (Project 111546)]
Project 4: Chimeric antigen receptor-engineered natural killer cells as a universal cellular therapeutic for adoptive cancer immunotherapy
This is a joint (Frankfurt/Mainz, Dresden, Essen, Heidelberg) translational immunotherapy program. It aims to combine Natural killer (NK) cells as effector lymphocytes with universal epitope-specific chimeric antigen receptors (UniCAR) with tunable activity.
Adoptive cell therapy based on CAR-engineered T cells have demonstrated remarkable efficacy in patients with B-cell malignancies. Yet, serious adverse events such as cytokine release syndrome or fatal outcome were frequently observed. This underscores the need for an improved understanding of how the interaction between CAR-engineered lymphocytes and the host immune system can be modulated to fine-tune effector cell activity. NK cells can enhance T-cell activation without production of cytokines linked to adverse reactions. In this project, the UniCAR is only activated upon cross-linking through a soluble tumor-targeting module carrying the UniCAR binding epitope, thereby achieving highest tumor specificity. Previous work from the contributing DKTK partner sites has demonstrated the versatility of the UniCAR approach in T cells, and showed that it is feasible to derive CAR-engineered, established human NK cells as an off-the-shelf cellular therapeutic. Focusing on advanced melanoma, we will investigate the antitumor activity of UniCAR NK cells in clinically relevant models. Recombinant targeting modules will be based on antibodies and soluble single-chain fragments of TCR specific for melanoma antigens. Promising combinations of UniCAR NK cells and distinct targeting molecules will be identified for subsequent translation into a biomarker-guided early phase clinical study employing the established pipeline of our consortium for GMP production of cellular therapeutics and the design and implementation of clinical trials in cancer immunotherapy.
[Funding 2017-2019: Deutsches Konsortium für Translationale Krebsforschung (DKTK)]
Project 5: Exploring a soluble T-cell receptor (TCR)-interleukin-15 superagonist complex as a novel, targeted immunostimulatory adjuvant to improve T/NK cell-mediated antitumor immunity to melanoma
This is a joint project together with AG Hartwig. It aims to explore the therapeutic potential of a novel targeted IL-15 superagonist composed of a soluble TCR specific for a cell surface melanocytic differentiation antigen, fused to an IL15/huIgG1-Fc (ILR-Fc) complex.
Therapeutic efficacy of adoptive cellular therapy in solid cancer such as e.g. melanoma is often hampered by nondurable antitumor immunity associated with insufficient trafficking, homing and persistence of T cells in an immunosuppressive tumor microenvironment. Interleukin (IL)-15 plays a pivotal role not only in T-cell but also NK-cell mediated immunity and might therefore represent a very promising candidate for improving antitumor responses under these conditions. In the proposed study we will thus explore a novel targeted IL-15 superagonist composed of a soluble HLA-independent single-chain (sc) TCR specific for a cell surface melanocytic differentiation antigen, fused to an IL15/IL15Rα/huIgG1-Fc (ILR-Fc) complex to confer high and prolonged bioactivity. The therapeutic potential of recombinant scTCR-ILR-Fc fusion protein to improve anti- melanoma responses will be examined in vitro and in vivo using clinically relevant mouse models after adoptive transfer of non-directed or antigen-TCR modified murine and human T cells or NK cells and combinations thereof. We propose that upon binding of the scTCR to the melanoma-associated cell surface antigen, signaling through the IL15/IL15Rα will substantially promote T-cell and NK-cell activation and induce cytolytic activity as recently reported for a HLA-A2-restricted p53-specific TCR linked to IL-2. Finally, targeting IL-15 might contribute to reduced nonspecific off-target activity often observed with cytokines used to boost immunity.
[Funding 2017: Inneruniversitäre Forschungsförderung (IUFF)]