CRC Transregio 221|Projects

Induction of the graft-versus-leukemia (GvL) effect in the absence of graft-versus-host disease (GvHD) by CD4+ T-cells directed against DM-sensitive antigens will be tested in murine models of allogeneic bone marrow transplantation both in a minor and a major mismatch setting. Using H2-O (murine HLA-DO) knock-out and transgenic mice as well as wild type mice as recipient strains will allow us to determine the role of the tissue-specific expression of H2-O for induction of GvL effect and GvHD. In addition, we aim to unravel regulation of HLA-DO expression in human cells. Finally, we will test effects of HLA-DO regulators on GvL effect and GvHD.

HLA-DPB1 mismatch antigens occur in allogeneic HSCT from unrelated donors and represent powerful leukemia rejections antigens, which can be efficiently targeted by T cells that have been genetically reprogrammed with allo-HLA-DPB1 specific T-cell receptors (TCR-DP). In this project we will develop an approach that allows for efficient and safe TCR-DP gene therapy in allogeneic HSCT. Special emphasis will be placed on the prevention of treatment-induced HLA-DP-specific alloreactivity to non-hematopoietic tissues (e.g. by „ON-Switch“ TCR or TCR-RNA transfer) and on the development of a novel humanized mouse model that enables the pre-clinical testing of this approach.

In this project, we apply the chimeric antigen receptor (CAR) technology to augment the GvL effect of HSCT. CARs are synthetic designer receptors that redirect the specificity of T cells to recognize malignant cells. We will pursue two novel CAR targets, i.e. FLT3 in acute myeloid leukemia and SLAMF7 in multiple myeloma, and apply cutting-edge strategies to increase their efficacy (e.g. through metabolic arming) and safety (e.g. with enhanced suicide genes). To avoid GvHD, we will generate CMV-specific (endogenous TCR) CAR-T cells and employ novel in vivo models to evaluate their ability to concomitantly battle against leukemia/myeloma and CMV infection.

We aim to develop novel bi-molecular hemibody constructs that address antigen combinations instead of single target molecules for high precision immunotherapy in the context of allogeneic HSCT. In a first step, we opt to improve the biochemical properties of the constructs focusing on stability, solubility and producibility. In a second step, we will establish humanized NSG mouse models to investigate pharmacokinetics and the specific requisites of dual antigen targeting, mimicking the clinical situation of leukemia patients undergoing allogeneic HSCT.

We hypothesize that oxidative stress confers immunological “hits” that predispose for leukemia relapse. The reconstituting donor immune system, which is fundamental for the GvL effect, is negatively impacted by oxidative stress. Our project addresses the importance of redox-balance after allo-HSCT. We will assess oxidative stress and its impact on immune reconstitution and function in allo-HSCT patients. We will test interventions for improving the T-cells’ anti-oxidative capacities together with other key functional properties. Our goal is to identify novel redox biomarkers predicting relapse risk that will allow us the rational design of targeted redox modulation for relapse prevention.

Relapse after alloHSCT is frequently associated with poor survival in patients with advanced B-cell malignancies. In order to investigate curative options for those patients, we are conducting in collaboration with the US National Cancer Institute (NCI) a first in human trial employing donor-derived CD19-CAR TSCMcells. In this project, we plan to perform a comprehensive and detailed immunomonitoring comparing TSCM-enriched CAR T cell products to conventional donor-derived CAR T cells from a prior NCI study conducted on a similar subset of patients. In particular, we will investigate potential benefits of the TSCM cell platform in terms of CAR T cell expansion, long-term persistence, CAR T cell functionality, safety profile and alloreactivity. Finally, by using retroviral insertion and TCR clonotype analyses, we will assess the differentiation trajectory of CD19-CAR and untransduced TSCMcells to determine how CAR signaling affect their self-renewal and multipotency.

The impact of selective and timed activation or inhibition of the type I interferon inducing cGAS / STING pathway during the course of allo-HSCT and its influence on the GvL effect as well as donor T cell activation and differentiation remains unknown. Using selective receptor ligands and inhibitors, and a combination of advanced in vivo models of leukemia and lymphoma, allogeneic transplantation models, and next-generation sequencing approaches, we aim to unravel the consequences of timed cGAS/STING activation / inhibition during allo-HSCT.