CAR T-cells Flashcards
What is adoptive T-cell immunotherapy?
Adoptive T-cell immunotherapy is the use of T-cells to kill the tumor cells.
T-cells recognise the tumor peptides presented by a HLA molecule on the tumor surface. They secrete cytokines and granzymes and kill the tumor cell.
What is Allogeneic hematopoietic stem cell transplant?
the patients stem cells and lymphocytes get replaced with that of a donor.
What is Tumor infiltrating lymphocytes (TIL) immunotherapy?
isolate TIL’s, ex vivo culture and enrich them for tumor specificity and then readminister into the tumor.
What is the concept of CAR T-cells?
The Chimeric Antigen Receptor (CAR) binds the tumor specific surface antigen and the T-cell receptor to activate T-cells by antigen recognition. The CAR is artificially made.
How do you make CAR T-cells?
First DNA synthesis with all the sequence you want and you put it in a viral vector, which will be transfected into a virus producer cell line which will produce retrovirus or lentivirus. We then infect peripheral blood T-cell with the viruses which will then start to produce CARs on the surface of the T-cell. This is the CAR T-cell we will then use for therapy.
How do you target on-target off-tumor toxicity?
To target on-target off-tumor toxicity we could use a carful target selection and dose escalation, local infusion, limit the CAR expression by CAR mRNA transfer and optimize CAR affinity.
Split CARs with a co-stimulatory domain could increase specific targeting of tumor cells. iCARs include a inhibitory CAR so there won’t be activation when this antigen present.
How do you target Toxicity related to CAR-T-cell over-activation?
It can lead to Cytokine Release Syndrome. This can be solved with a switch in the CAR with adaptor molecules or using dimerizing agents so we control when the T-cell will be activated or not. We could give drugs that inhibit phosphorylation of downstream molecules of the T-cell activation.
How do you adapt CAR T-cells against antigen escape?
Antigen escape can be solved by a mixture of different CAR-T cells or CAR-T cells targeting multiple antigens. Or making armoured CAR-T-cells which express BiTEs that attract different T cells which enhance the elimination.
How do you improve CAR T-cell persistence?
CAR-T cells are more effective when they stay in the body longer. Selection of an appropriate co-stimulatory molecule is important, 4-1BBL can induce activation of DC to secrete supportive cytokines which can increase persistence. The use of less-differentiated T-cell subsets will have greater proliferative potential.
How do you overcome the immunosuppressive tumor microenvironment?
Knock-out immune checkpoint receptors with for example CRISPR. Or secreting various cytokines/chemokines to alter the inflammatory milleu of the TME. Armoured CAR-T-cells co-expressing immunomodulatory ligands (e.g. CD40) also alter the inflammatory mileu and increase the immunogenicity of tumors.
How can you evaluate CAR T-cell efficacy?
You can use flow cytometry for detection and immunophenotyping of Tcells. With qPCR you can measure vector copy number in peripheral blood which detects the CAR-T-cell persistence. Genome sequencing to find integration sites of the vector to monitor the clonality.
