4 research outputs found
Fine-tuning the antigen sensitivity of CAR T cells: emerging strategies and current challenges
Chimeric antigen receptor (CAR) T cells are āliving drugsā that specifically
recognize their target antigen through an antibody-derived binding domain
resulting in T cell activation, expansion, and destruction of cognate target
cells. The FDA/EMA approval of CAR T cells for the treatment of B cell
malignancies established CAR T cell therapy as an emerging pillar of modern
immunotherapy. However, nearly every second patient undergoing CAR T cell
therapy is suffering from disease relapse within the first two years which is
thought to be due to downregulation or loss of the CAR target antigen on cancer
cells, along with decreased functional capacities known as T cell exhaustion.
Antigen downregulation below CAR activation threshold leaves the T cell silent,
rendering CAR T cell therapy ineffective. With the application of CAR T cells for
the treatment of a growing number of malignant diseases, particularly solid
tumors, there is a need for augmenting CAR sensitivity to target antigen present
at low densities on cancer cells. Here, we discuss upcoming strategies and
current challenges in designing CARs for recognition of antigen low cancer cells,
aiming at augmenting sensitivity and finally therapeutic efficacy while reducing
the risk of tumor relapse
CAR Triggered Release of Type-1 Interferon Limits CAR T-Cell Activities by an Artificial Negative Autocrine Loop
The advent of chimeric antigen receptor (CAR) T cells expedited the field of cancer immunotherapy enabling durable remissions in patients with refractory hematological malignancies. T cells redirected for universal cytokine-mediated killing (TRUCKs), commonly referred to as āfourth generationā CAR T-cells, are designed to release engineered payloads upon CAR-induced T-cell activation. Building on the TRUCK technology, we aimed to generate CAR T-cells with a CAR-inducible artificial, self-limiting autocrine loop. To this end, we engineered CAR T-cells with CAR triggered secretion of type-1 interferons (IFNs). At baseline, IFNĪ± and IFNĪ² CAR T-cells showed similar capacities in cytotoxicity and cytokine secretion compared to conventional CAR T-cells. However, under āstressā conditions of repetitive rounds of antigen stimulation using BxPC-3 pancreas carcinoma cells as targets, anti-tumor activity faded in later rounds while being fully active in destructing carcinoma cells during first rounds of stimulation. Mechanistically, the decline in activity was primarily based on type-1 IFN augmented CAR T-cell apoptosis, which was far less the case for CAR T-cells without IFN release. Such autocrine self-limiting loops can be used for applications where transient CAR T-cell activity and persistence upon target recognition is desired to avoid lastin
CopR, a Global Regulator of Transcription to Maintain Copper Homeostasis in Pyrococcus furiosus
Although copper is in many cases an essential micronutrient for cellular life, higher concentrations are toxic. Therefore, all living cells have developed strategies to maintain copper homeostasis. In this manuscript, we have analyzed the transcriptome-wide response of Pyrococcus furiosus to increased copper concentrations and described the essential role of the putative copper-sensing metalloregulator CopR in the detoxification process. To this end, we employed biochemical and biophysical methods to characterize the role of CopR. Additionally, a copR knockout strain revealed an amplified sensitivity in comparison to the parental strain towards increased copper levels, which designates an essential role of CopR for copper homeostasis. To learn more about the CopR-regulated gene network, we performed differential gene expression and ChIP-seq analysis under normal and 20 Ī¼M copper-shock conditions. By integrating the transcriptome and genome-wide binding data, we found that CopR binds to the upstream regions of many copper-induced genes. Negative-stain transmission electron microscopy and 2D class averaging revealed an octameric assembly formed from a tetramer of dimers for CopR, similar to published crystal structures from the Lrp family. In conclusion, we propose a model for CopR-regulated transcription and highlight the regulatory network that enables Pyrococcus to respond to increased copper concentrations
Designed Ankyrin Repeat Protein (DARPin) to target chimeric antigen receptor (CAR)-redirected T cells towards CD4(+)T cells to reduce the latent HIV(+)cell reservoir
Chimeric Antigen Receptor (CAR)-redirected T cells show great efficacy in the patient-specific therapy of hematologic malignancies. Here, we demonstrate that a DARPin with specificity for CD4 specifically redirects and triggers the activation of CAR engineered T cells resulting in the depletion of CD4(+)target cells aiming for elimination of the human immunodeficiency virus (HIV) reservoir