flow cytometric assessment of oxygen-dependent car expression in car-t cells

<meta charset="utf8"></head><body>Functionele validatie van hypoxie-gevoelige CAR-T-cellen voor selectieve tumoren

Chimeric antigen receptor T cell (CAR-T) therapy has represented a significant breakthrough in cancer treatment. Since the Food and Drug Administration (FDA) approved the first CAR-T therapy for treating advanced/resistant lymphoma and acute lymphoblastic leukemia in 20171,2,3, 10 CAR-T therapies targeting CD19 or B-cell maturation antigen (BCMA) have received approval globally4. However, despite extensive research, replicating the remarkable efficacy of CAR-T therapy in treating hematological malignancies remains challenging for its application to solid tumors5,6,7,8.
The immunosuppressive tumor microenvironment (TME) is a primary contributor to the poor efficacy of CAR-T in the solid tumor setting. TME impedes the activity and survival of CAR-T cells due to insufficient nutrients, hypoxia, an acidic pH, and the accumulation of metabolic waste9,10,11,12. Further hostility comes from infiltrating immunosuppressive cells such as regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAM), which, alongside tumor cells, secrete immunosuppressive cytokines that cause additional inhibition of CAR-T cells once they enter the tumor13,14.
Apart from the unsatisfactory therapeutic efficiency, safety issues are another Achilles&#39; heel of CAR-T cells when dealing with solid tumors15,16. The safety concern arises from the fact that none of the tumor-specific antigens (TSA) identified so far are strictly restricted to tumor cells. In other words, the tumor-associated antigens (TAA) chosen as the target of CAR, although showing higher expression in tumor cells, are often also expressed by normal tissues17. On-target, off-tumor effects could therefore occur from the unexpected activation of CAR-T cells upon CAR efficiently recognizing normal tissues, leading to cytokine release syndrome (CRS), CAR-T-related encephalopathy syndrome (CRES)18, and other adverse outcomes19.
Many strategies have been explored to avoid such effects, including decreasing the affinity of CAR to allow CAR-T cells to distinguish tumor cells from normal cells based on the expression levels of the targeted TAA; equipping CAR-T cells with an off switch, such as a suicide gene or elimination marker to promote their elimination upon unexpected activation; partitioning the CD3&#950; and co-stimulatory signals into two CAR moieties, whose simultaneous engagement is consequently required for effective activation of CAR-T cells; utilizing a synthetic Notch (synNotch)-based circuit that restricts the activity of CAR-T cells to targeted cells co-expressing two different TAAs; and engineering CAR-T cells to attain TME sensitivity by implementing a mechanism to tune CAR expression to changing environmental cues20,21,22,23,24,25,26.
A key consideration in the TME sensitivity option outlined above is the low oxygen level in the TME due to the rapid proliferation of tumor cells. The accommodation of tumor cells to hypoxia hinges on the activation of hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcriptional factor consisting of an inducible subunit, HIF-1&#945;, and a constitutively expressed subunit, HIF-1&#946;27. Under normoxic conditions, the HIF-1&#945; protein undergoes ubiquitination and rapid proteasomal degradation, dependent on its oxygen-dependent degradation domain (ODD)28. When the cellular supply of oxygen becomes limited, HIF-1 is stabilized and activates the transcription of its downstream target genes by binding to hypoxia-response elements (HREs)29. Given the nature of ODD and HRE as oxygen-sensitive elements, they have been explored to realize the conditional expression of CARs within the hypoxic TME30. Here, we present a protocol focusing on methods for phenotypic and functional characterization of hypoxia-sensitive CAR-T cells, preceded by a brief description of the CAR design and the preparation procedures of these cells. This protocol intends to provide a useful guideline for exploiting hypoxia-responsive CAR to generate CAR-T cells with restrained off-tumor toxicity.

<meta charset="utf8"></head><body>Auteur in de schijnwerpers: Vooruitgang in hypoxiegevoelige CAR-T-therapie voor verbeterde kankerimmunotherapie

Generatie en functionele verificatie van hypoxie-gevoelige chimere antigeenreceptor-T-cellen

Our research primarily focuses on cancer immunotherapy, particularly in CAR T-cell-based immunotherapy. We have been exploring novel strategies during last 10 years to enable CAR T-cells to specifically target a tumor with minimizing the side effect or even no side effect at all. Novel strategy have been persistently explored to improve the safety and efficacy of the CAR T-cell-based immunotherapy, in particularly by targeting tumor microenvironment, such as hypoxia-conditioned CAR, as exemplified in this protocol.Interestingly, recent study demonstrated that hypoxia-condition CAR T not only greatly improved the safety profile, but also reduced the CAR T exhaustion and enhanced the efficacy in solid tumors. Hypoxia is a characteristic feature of tumor microenvironment. Our research aims to help researchers in the field of cancer immunotherapy understand the concept of hypoxia-sensitive CAR T-cells, their construction and how to establish hypoxia models for evaluation.Our laboratory will continue exploring new strategies for constructing CAR T-cells to enhance their tumor-curing efficacy, safety profile and cost effectiveness.

Flowcytometrische beoordeling van zuurstofafhankelijke CAR-expressie in CAR-T-cellen

flow-cytometric-assessment-oxygen-dependent-car-expression-car-t

Research

JoVE Journal

Cancer Research

Flow Cytometric Assessment of Oxygen-Dependent CAR Expression in CAR-T Cells

29 Views. To begin, plate the cultured CAR-transduced T cells into two 12-well plates containing two milliliters of TGM. Place one plate directly in a humidified incubator under 5%carbon dioxide at 37 degrees Celsius. Place the other plate in a mobile carbon dioxide, oxygen nitrogen incubator chamber with the oxygen level preset at 1%Collect 500, 000 cells from the plates every 24 hours under both conditions into 1.5 milliliter micro centrifuge tubes.Centrifuge the tubes at 500 G for five minute...