Exam 4 Cell-based Therapeutics 1 Flashcards
What is the rank of the different types of medicines from smallest to largest?
small molecules → large molecules → biologics → cell-based therapies
What are the two classes of cell-based therapies?
- stem cells and stem cell-derived products
2. immunotherapies
What is some information about stem cells and stem cell-derived products as cell-based therapies?
- does not involve immune cells → does not mobilize the immune system
- stem cells can differentiate into any tissue and it utilizes the cell as a drug
- examples: hematopoietic, mesenchymal, embryonic, umbilical cord blood
What is some things to know about immunotherapies?
- involve immune cells → activates the immune system
- cancer vaccines and cell based immune therapies
- examples: dendritic cells (typically vaccines), genetically modified lymphocytes, activated lymphocytes (TIL, NK, T), cancer cells chemically modified or unmodified
- immunotherapies include native and cell-based gene therapies (genetically engineered lymphocytes)
What are the two types of cell-based therapies?
- stem cell therapy
2. engineered (immune) cell-based therapy
What are some things to know about stem cell therapy?
- does not involve immune cells
- uses stem cells that can virtually become any tissue/cell in the body depending on the source
- embryonic cells are pluripotent which means they can become any type of cell
- utilizes cells that are unspecialized and can be self-renewed and are pluripotent
What are some things to know about engineered (immune) cell based therapy?
- the drug substance is a gene vector
2. utilizes mature blood cells (immune cells aka lymphocytes) that will typically get re-infused back to the patient
What does cell based therapy entail?
engineered/modified cells
What does native cell therapy entail?
not modified cells
What is the nomenclature of cell based therapy?
- cell based therapy is immunotherapy when it utilizes immune cells such as CAR-T
- cell based therapy is just cell therapy when it does not involve the immune system such as stem cell tissue regeneration
What is a stem cell?
a single cell that can replicate itself or differentiate into many cell types (can even become a blood cell that can then be used for immunotherapy)
What are the uses of stem cells in cell therapy?
- can be used in cell replacement therapy (for Alzheimer’s, Parkinson’s, diabetes, arthritis)
- adult stem cells are less versatile than embryonic stem cells (since they are restricted to whatever organ they came from)
- only 22 embryonic cell lines are eligible for federal funding in the US
- no approved FDA products based on tissue-regenerative stem cells yet
What are the three different types of stem cells?
- totipotent
- pluripotent
- multipotent
What are totipotent stem cells?
each cell can develop into a new individual → examples include cells from early (1-3 days) embryos
What are pluripotent stem cells?
cells can form any (over 200) cell types → examples include some cells of blastocyst (5 to 14 days)
What are multipotent stem cells?
cells differentiated but can form a number of other tissues → examples are fetal tissue, cord blood, and adult stem cells
What is unique about multipotent stem cells?
can only become a certain tissue from where it came from
What types of stem cells are most versatile?
totipotent and pluripotent
With cell therapy clinical trials, which cells are most utilized?
hematopoietic cells → mesenchymal stem cells → lymphocytes → dendritic cells
What are some examples of cancer immunotherapies?
- checkpoint inhibitors
- cytokines → proteins that signal the immune system
- cancer vaccines
- oncolytic viruses
- adoptive cell transfer → somebody adopts your cells that gets transferred to an individual for therapy
What are the types of cell therapies that are immunotherapies?
- adoptive cell transfer → involving CAR-T, CAR-NK, TILs, and native T/NK cells
- cancer vaccines → involving dendritic cells
Any cell based therapy that is genetically modified is also a what?
gene therapy
What is gene therapy?
putting a gene into a vector or delivery system and infuse it into the patient in vivo as therapy
What is cell-based therapy?
uses cells as a vector (aka a carrier) in which you take immune cells and engineer them to infuse it back into the patient → cell becomes drug product and gene is the drug substance
With cell-based immunotherapies, what does it mean for it to be expanded?
the cells are taken out of the blood and expanded in a lab to get billions of cells that can then be put into a bag to be infused back to the patient
What can you do with dendritic cells as cell-based immunotherapy?
dendritic cells can be expanded with or without activation → lead to dendritic cell vaccine
What can you do with T cells for cell-based immunotherapy?
- expansion with or without activation → TILs
- add TCR (T cell receptor) → TCR
- add CAR (chimeric antigen receptor) → CAR-T
What can you do with NK cells with cell-based immunotherapies?
add CAR (chimeric antigen receptor) → make CAR-NK (but since it was not expanded, it is not as durable as the other therapeutics)
What are the different types of adoptive cell-based immunotherapies?
- native immune cells (activated) → most common in which you take cells, expand them, and put it back into the patient
- TIL (tumor infiltrating lymphocytes) → cells associated with a tumor and are primed/activated to fight cancer easily
- TCR (T cell receptors) → engineered cells based on cell specific receptors
- CAR-T or CAR-NK (chimeric antigen receptor T or NK cells) → synthetic genetic construct targeting a tumor antigen, CAR macrophages under development →→ basically genes that force immune cells to find the cancer and stick to them like velcro
What is taa and tsa?
taa = tumor associated antigen → other cells that can carry/express antigens that cancer cells express
tsa = tumor specific antigen → every cancer cells express proteins on surface (tsa) but healthy cells do not
Most cell-based therapy clinical trials involve which therapy type?
most products are CAR-T cells (has been studied the longest and FDA has approved products)
What are some examples of products that are regulated by the FDA Office of Cellular, Tissue, and Gene Therapy?
- somatic cell therapies
- gene therapies → such as cell-based therapies like CAR-T which utilize immune cells and are genetically engineered
- viral therapies like oncolytic viruses
- immunotherapies like tumor vaccines and checkpoint inhibitors
- xenotransplantation
- tissue engineering
- OCTGT product + device
About how many cell-based therapies have been approved by the FDA?
almost 20 therapies in the US! in which 5 are CAR-T therapies that target blood cancers and the rest are hematopoietic stem cell transplants
What are the 5 approved CAR-T cell based therapies that have been approved by the FDA?
- Kymriah for B-cell ALL (leukemia)
- Yescarta for Non-Hodgkin’s lymphoma
- Tecartus for mantle cell lymphoma
- Abecma for multiple myeloma
- Breyanzi for large B-cell lymphoma
How can stem cell treatments in the US claim to cure blindness to lung diseases?
they take cells from fat tissues or bone marrow and infuse it back to the patient
What are the indications of US cell therapy approvals by the FDA?
- FDA approved stem cell therapy products are for hematopoietic stem cell transplantation → cells become concentrated and are infused back to patient to become healthy adult cells
- FDA approved cell based therapy products (CAR-T) are for blood cancers
- no other stem cell therapy is approved in the US
FDA approved cell-based therapies are also called what?
immune cell therapies
What are some indications that have been FDA approved for cell-based therapy?
certain cancers and disorders of the blood and immune system
What are some indications that are not FDA approved for cell-based therapy?
arthritis, injury related pain, chronic joint pain, blindness, anti-aging or other diseases or health issues
When are stem cell therapies considered drugs?
- non exempt from regulation: more than minimal manipulation
- exempt from regulation: minimal manipulation and homologous use → such as if cells and/or tissue are removed from and implanted into the same individual within the same surgical procedure and remain in their original form
What do clinics that say they do stem cell therapies actually do?
liposuction to get solid fat → mincing, collagenase, inactivation (aka processing) to get digested fat in liquid form → RBC lysis, washes, centrifuge, filter it to get a product for injection that consists of a fatty layer (top), aqueous layer (middle), and SVF on the bottom which is stromal vascular fracture that has mesenchymal stem cells (stem cells of adult tissue) that can then become something
What are the clinics’s argument against FDA warnings about these clinics?
they are:
- not manipulating cells anymore than minimally → BUT FDA states that they take it from fat, centrifuge it and put it back into the patient which is more than minimally
- freedom of choice → my cells my body
What was the outcome of the FDA winning the case against the Florida stem cell clinic?
the FDA can now regulate US stem cell clinics
What are the 4 basic criteria that cell-based therapies must meet in order to be un-regulated and not treated like a drug?
- minimally manipulated → cannot change the property of cells via filtration, centrifugation, or separation
- homologous use → cells has to produce same duty in the recipient and donor
- HCT/P (human cell or tissue product) combined with device or drug that is sterilizing, preserving, or storage agent → has to be just cells
- the HCT/P does not have a systemic effect and is not dependent upon the metabolic activity of living cells for its primary function → has to locally act in the tissue it’s going in
What are some examples in which stem cell therapies are regulated and non-regulated?
non-regulated: injecting bone cells into bone
regulated: cultured cells, sorted cells, cells in 3D scaffolds, engineered cells
What is the basis behind hematopoietic stem cell transplantation?
hematopoietic stem cells have the ability to divide and multiple (self renew) and to develop (differentiate) into different types of mature blood cells → they are used to treat patients with disorders of the blood, including some cancers
What are some things to know about hematopoietic stem cell transplantation?
- sources: bone marrow (autologous), cord blood (unrelated)
- FDA regulated unless it meets exemptions
- CD34 cells are extracted from the blood and concentrated so that they can be injected back into the blood to become blood cells → homologous therapy!
Cell therapy can also be used for what diseases?
- HIV → HIV has CD34 cells and there could be anti-HIV CAR-modified T cells
- COVID-19 → cells can be primed or engineered to target COVID as dendritic cells can prime T cells for immune response (mesenchymal cells are also being researched)
How do NK cells attack cancer cells?
NK cells release things that can pierce and kill cancer cells through contact in which contact/connection triggers the killing of the cancer cells
How can immune cells kill cancer cells?
- to invoke the immune system, you need a target
- this is called an antigen and is usually on the surface of the cancer cell
- antigens can be targeted by antibodies or by cells engineered to recognize it (such as a chimeric antigen receptor)
What is one advantage of NK cells over T cells?
NK cells don’t need protein like T cells do
How are the killer immune cells go to action?
- immune cells can be redirected to attack a pathogen by engineering synthetic receptors that can recognize antigens present on specific cancers (via contact)
- they do this by releasing proteins (cytotoxic granules) that kill target cells
What is the step by step action of NK cell killing a cancer cell?
killer T cell docks onto a target cell → kill T cell releases enzyme into target cell which are pore forming proteins that form holes on the membrane of the cancer cell to kill it → target cell death
What are the two immune responses to pathogens?
- innate immunity
2. adaptive immunity
What are some examples of things part of innate immunity?
epithelial barriers, phagocytes, complement, NK cells
What are some examples of adaptive immunity?
B lymphocytes that produce antibodies and T lymphocytes that produce effector T cells
What is the role of innate immunity and adaptive immunity?
innate immunity is right away and if it can’t do its job then up to a week later the T cells come in and adaptive immunity kicks in
When infused, how long do NK cells or T cells last?
NK cells will last a week or 2 weeks but T cells can last for months (since they are living drugs)
What is autologous cell based therapy?
cells from your own body (you are your own donor) → no GvHD (graft vs host disease), higher doses feasible, harder to source (maybe don’t have enough or not strong enough), immune compromised
Most CAR-T cell therapy is what?
autologous → but it is hard since most patients don’t have enough cells
What is allogeneic cell based therapy?
cells from a different donor → easier to source, “off the shelf”, can induce GvHD immune response (since donors don’t always match)
Who is cell-based immunotherapy for?
- patients with advanced cancers (stage 4)
- patients who have not responded to primary treatment (chemotherapy/radiotherapy/surgery)
- patients whose cancers have returned (and spread) after initial treatment → refractive cancers
Why is CAR-T cell therapy usually reserved for terminal cancer patients?
if they have failed all else since CAR-T cell therapy is really aggressive and expensive
What is an example using patients with acute myeloid leukemia (ALL)?
- most patients with pre-B ALL achieve sustained remission with chemotherapy
- approximately 15-20% relapse, requiring intensification of therapy and many benefit from stem cell transplantation
- greatest benefit from HCT is when patients have little disease remaining (MRD negative)
- challenges remain for some patients that are refractive and unable to achieve remission
What are the four sources of cells for immunotherapy?
- peripheral blood (circulating blood in the body) → autologous transfer, patient specific, 10% NK/T cells
- cord blood → allogenic, can be cryopreserved, 30% NK/T cells
- cell lines → commercially available (aka off the shelf), allogenic
- induced pluripotent stem cells → allogenic, can be cryopreserved, off the shelf
What are the three different types of donors?
- sibling donor → can induce GvHD
- matched unrelated donor → 60-70% patients have a donor match, 50-60% GvHD rates
- haploidentical family donor → needs profound immunosuppression, 10-15% failure rate
What are the principles behind CAR-T cell-based therapy?
- cells are removed, genetically engineered, expanded, and delivered back to the patient
- patients are pre-conditioned with chemotherapy to restrain immune response
doctor draws blood (about 100 mL) → cells will be frozen right away and shipped over to the company which will then thaw the cells and genetically engineer them with a virus where the virus injects cells with a gene and the gene will express a protein on the cell → cells are expanded to make a dose → dose is bagged, frozen, and shipped back to the hospital about 30 days later) and the patients get infused
What is TIL therapy?
involves no genetic engineering in which they take a tumor from a patient and take the T cells from the patient and then infuse them back in after expanding them
What is CAR-T therapy?
cells are taken from the patient and genetically engineered to express a gene that will find cancer and recognize it (takes about 30 days to make) → a very long process which is why this is the last resort
What are the two main components of CAR-T therapy?
CAR: chimeric antigen receptor (gene) → expresses a protein that immune cell recognizes in cancer cells →→ drug substance is the gene!
T cells or NK cells or macrophages or dendritic cells → any immune cell of the blood that has the ability to fight any type of foreign cell and engineer it to recognize cancer cells specifically
What are CARs (chimeric antigen receptors)?
- CARs are engineered molecules expressed on the surface of immune cells that can recognize specific proteins on target (cancer) cells and deliver an activation signal to the cells
- activation signals result in killing of target and are given through co-stimulatory domains such as 4-1BB, CD28, CD8
- can be designed to target tumor specific antigens (TSAs) or tumor associated antigens (TAAs) → TAAs are less specific but more common since healthy tissues express them too like CD19 but TSAs are more specific to cancer cells and not healthy cells but harder to identify
Cancer cells express what?
TAAs and TSAs → TSAs are more of the ideal target
What are the sources of immune cells?
- peripheral blood
- cord blood
- stem cells
- cell lines
What is the drug product of cell-based therapy?
immune cell + gene (example would be CAR-T/NK cell) → aka whole cell with the genetic engineered component
What is the drug substance in cell-based therapy?
engineered molecular component (chimeric antigen receptor or gene) → just the gene itself (API)
What is the structure of chimeric antigen receptors (CARs)?
top part that sticks out of the membrane are the antibody fragments that recognize proteins on cancer cells and bottom part contains co-stimulatory domains that tells the cell to kill once it makes contact with a cancer cell
First generation CARs have what?
single signaling domain (just CD28)
Second generation CARs have what?
dual-signaling domain (both CD28 and CD3)
Third generation CARs have what?
multiple signaling domains (CD28, CD3, 4-1BB or OX40)
More than one signaling domain does what?
helps killing of the target
What are the main chimeric antigen receptor domains?
- antibody binding (scFv) → binds to the cancer cell
2. intracellular/co-stimulatory domains → send cytotoxic/killing/activation signals →→ trigger drug activity!
What does the transmembrane domain do?
is the bridge that connects the outside and inside
What are some properties of T cell receptors (TCRs)?
- modularly composed multi-protein complex
- recognizes antigen in the context of MHC
- restricted to processed peptide antigen
- low affinity interaction
- most TCRs require co-receptors for synapse formation (with the exception of some affinity matured TCRs)
What are some properties of chimeric antigen receptors (CARs)?
- modularly composed one-chain protein
- recognizes antigen independently of MHC
- not restricted to peptide antigens but restricted to antigens on the surface of target cells
- antibody mediated high affinity interaction
- does not require co-receptors
What is the main difference between CARs and TCRs?
- both are engineered receptors on T cells but CARs are completely synthetic (is made in a lab) while TCRs are little receptors that natural T cells express when interacting with cancer cells → makes the activation status of the cell
- TCRs can be extracted from T cells and used to engineer other T cells so they all have the same activation status
What is one important thing to note?
activity of the drug utilizes the native activity of immune cells → T cells can kill cancer cells no matter what
