CAR T-cell therapy

Question 1

What is the function of Helper T cells (CD4)?

Answer 1

Upon binding to a specific antigen, helper T cells secrete cytokines to stimulate the differentiation of B cells into plasma cells (antibody-producing cells)

Question 2

What is the function of Cytotoxic cells (CD8)?

Answer 2

Upon activation, cytotoxic T cells bind and kill infected cells and cancer cells (or any substance marked as foreign by the immune system)

Question 3

How are cytotoxic T cells activated?

Answer 3

By simultaneous interactions of surface molecules (TCR-MCR and CD28-CD80) between cytotoxic T cell and APC cells

These two cell stimulating interactions result in T cell proliferation and activation

Question 4

What is the first T cell activation signal?

Answer 4

Between TCR of the cytotoxic T cell and MHC I of the APC

Question 5

What is the second T cell activation signal?

Answer 5

Between CD28 of cytotoxic T cell and CD80 of APC

Question 6

What are the co-stimulators for T cell activation?

Answer 6

CD80/86

Question 7

What is the TCR-CD3 complex?

Answer 7

It is a signalling complex comprised of TCR and three CD3 subunits

When TCR-CD3 is activated by MHC I from APC, it will bind ZAP70 ro initiate the activation of T cells via TCR pathway

see slide 5

Question 8

How do T cells actually destroy targeted cells?

Answer 8

Cytotoxic T cells release perforin, granzyme, and granulysin

All substances are involved in the destruction and breakdown of cells

Question 9

What are the functions of perforin?

Answer 9

Forming pores on target cell membranes

Question 10

What are the functions of granzyme?

Answer 10

Inducing apoptosis of target cells

Question 11

What are the functions of granulysin?

Answer 11

Forming pores in microbial cell walls

Question 12

What are some techniques used by cancer cells to evade immune response?

Answer 12

• Overexpression of CD47 (binds to SIRPa)
• Downregulation of MHC I molecules
• Lack of costimulatory signals (downregulation of CD80)
• Secretion of immunosuppressive molecules (recruited immune cells are inactivated)
• Modulation of antigens (old T-cells can no loger bind to cancer cells)

Question 13

What is CAR T-cell therapy?

Answer 13

Chimeric antigen receptor (targeting a specific antigen in cancer cells such as CD19)

CAR T cells are engineered T cells with CAR on the surface

Question 14

In general, how are CAR T cell therapies designed?

Answer 14

• Collect T cells from a patient’s blood
• Add the chimeric gene (encoding CAR) into the T cells in a laboratory (gene should be unique to cancer)
• Grow and collect CAR T cells in the laboratory
• Infuse CAR T cells into the patient

Question 15

What is the latest generation of CAR T cell therapies to be approved for regular use?

Answer 15

2nd generation CAR T cell therapies

Question 16

What are the components of the chimeric antigen receptor (CAR)?

Answer 16

• scFv (single-chain variable fragment)
• Hinge
• Transmembrane domain
• CD3 (activates TCR signalling pathway)

Question 17

What is a single-chain variable fragment (scFv)?

Answer 17

It is a fusion protein of the variable regions of the heavy chain and light chain.

The two are combined into a single unit

Question 18

What is most significant difference between different generations of CAR T cells?

Answer 18

Newer generations have more costimulators

1st gen: 0 co-stimulators (low efficacy)

2nd gen: one co-stimulator along with CD3

3rd gen: two co-stimulators along with CD3

Question 19

What are some challenges associated with CAR T cell therapy?

Answer 19

• Time consuming
• High cost (about $500,000 per treatment course)
• Hostile tumour microenvironment
• T cell exhaustion (loss of effector function due to prolonged antigen stimulation)
• Regulatory hurdles

Question 20

What are some characteristics of tumour cells that express CD19?

Answer 20

Biomarker for lymphoma and leukemia (universally expressed in B-cell avute lymphoblastic leukemia)

Serves as a target for CAR T-cell therapy

Question 21

What are some characteristics of B-cell maturation antigen (BCMA)?

Answer 21

Biomarker for multiple myeloma

Overexpression and activation are associated with multiple myeloma

Member of TNF-receptor superfamily

Question 22

What are some characteristics of the drug Kymriah (tisagenlecleucel)?

Answer 22

• 4-1BB as the co-stimulator
• Targeting CD 19 antigen

Indicated for B-cell precursor acute lymphoblastic leukemia and diffuse large B-cell lymphoma

Question 23

What are some characteristics of the drug Yescarta (axicabtagene ciloleucel)?

Answer 23

• CD28 as the co-stimulator
• Targeting CD19 antigen

Indicated for Diffuse large B-cell lymphoma and Follicular lymphoma

Question 24

What are some characteristics of the drug Tecartus (brexucabtagene autoleucel)?

Answer 24

• CD28 as the co-stimulator
• Targeting CD19 antigen

Indicated for Mantle cell lymphoma

Question 25

What are some characteristics of the drug Breyanzi (lisocabtagene maraleucel)?

Answer 25

• 4-1BB as the co-stimulator
• Targeting CD19 antigen

Indicated for large B-cell lymphoma

Question 26

What are some characteristics of Abecma (idecabtagene vicleucel)?

Answer 26

• 4-1BB as the costimulator
• Targeting B-cell maturation antigen (BCMA)

Indicated for multiple myeloma

Question 27

What are some characteristics of Carvytkti (ciltacabtagene autoleucel)?

Answer 27

• 4-1BB as the co-stimulator
• Targeting B-cell maturation antigen (BCMA)

Indication for relapsed/refractory multiple myeloma

Question 28

What is the advantage of using 4-1BB as a costimulator vs CD28?

Answer 28

4-1BB as a co-stimulator for CAR T cell therapies shows better survival in B-cell acute lymphoblastic leukemia