Chimeric antigen receptor T cells , immunotherapy

1. CAR–T CELLS
IN ONCOLOGY
Dr K VENKATA PRADEEP BABU

2. CHIMERIC ANTIGEN
RECEPTOR –T CELLS
IN ONCOLOGY

4. William b Coley
: Father of
immunotherapy

7. IMMUNOTHERAPIES IN ONCOLOGY – A TIMELINE
2018
Car T cell
therapy

8. IMMUNOTHERAPIES- TYPES
• Although approval was limited to few subsets, immunotherapy itself
constitutes a wide variety of therapies.
It includes
• Anti-cancer vaccines
• Oncolytic viruses
• Ex-vivo modification of T cells and Natural killer cells (Car-T cells)
• Administration of proteins and antibodies that can stimulate
(Accelerate)the natural immunity against the cancer cells
Inhibit (break the brakes) the checkpoints inhibiting this
immune cells action against tumors.

9. Not all FDA approvals are exciting and are of realistic value!!

10. This FDA approval :A new Era in Oncology
• The US FDA’s approval of Kymriah―developed by Novartis and
university of Pennsylvania―in August 2017 is the first CAR T cell
therapy targeting CD19 approved to treat refractory or relapsed (r/r)
B-cell precursor ALL for patients under the age of 25.

11. Within two months… second approval

12. Basic principle -ACT
• T cells are collected from a patient.
• Genetically engineered to express chimeric antigen receptors (CARs)
that recognize the patient’s cancer cells.
• Re-infused back to the patient Adoptive cell transfer, or ACT.
• These engineered cells circulate in the bloodstream, becoming “living
drugs” that target and kill the antigen-expressing cancer cells.

13. Steps in car T
cell
production
and therapy

14. History and facts
• T cells recognize, infiltrate and eradicate cancer cells expressing foreign tumor-
associated antigens (TAAs)  A well known fact.
• TILs from patients with metastatic cancer can be expanded ex vivo and re-infused
back into patients to enhance tumoricidal effects  first used to treat
melanomas at the National Cancer Institute in the 1980’s .
• Taken this idea a step further, other groups genetically engineered TCRs to
recognize specific TAAs.
• TCRs engineered to recognize MART-1 antigen, which is highly expressed on
malignant melanoma cells, resulted in T cells with high avidity for malignant cells.
Adoptive transfer of these engineered cells led to tumor regression in a number
of patients (Morgan, 2006).

15. How tumours escape T cell surveillance ?
Mechanisms of tumor cells to escape from TCR mediated immunity:
• Downregulation of HLA expression: T-cell can recognize only HLA bound Ag,
tumor cells downregulate expression HLA molecule and escape immunity
• Lack of co-stimulatory or presence of inhibitory (PDL-1)molecule  leads to
decreased T-cell activation

16. How Car-T cells overcome the inhibtion?
• Characteristics of CAR-T cells:
• CARs recognize unprocessed Ag independent of HLA expression
• CARs can modify the T-cells to bind carbohydrates /ganglioside
/proteoglycans in addition to proteins, thus expanding the range of potential
targets
• 2nd and 3rd generation CARs contains co-stimulatory molecules and thus
effectively activate T-cells

17. Clinical applications of CAR-T Cells
• Cancers:
• ALL: targeting CD19
• CLL: targeting CD19
• MM: targeting CD19
• Lymphoma: targeting CD19 & CD20
• AML: targeting Lewis Y Ag or CD33
• Neuroblastoma: against GD2
• Autoimmune diseases

18. What is chimera ?
• ‘Chimera’ refers to Greek mythology where Homer described a fire-spitting
monster with the head of a lion, the body of a goat and the tail of a serpent.
• The term chimerism was first introduced into medicine in 1951, when they
wrote that ‘a chimera is an organism whose cells derive from two or more
distinct zygote lineages’,

19. What is chimeric antigen receptor ?
• The CAR is a fusion antigen receptor:
A fusion of
• Part of Monoclonal antibody
• Part of T cell receptor

20. How engineered antigen is expressed on T cell?
• The most commonly used method to stably insert DNA constructs encoding CARs into
T cell genomes is viral vector transduction with either Retroviral vector or lentiviral
vector.
When the CAR binds to a tumor antigen on the surface of a target cell, the CAR T cell
will induce apoptosis using the same mechanism as normal T cells.

21. Evolution of CARs
• The first CAR T cells were in Israel in late 1980s .
• Chimeric antigen receptors (CARs) are
composed of three components:
1. Extracellular antigen-binding domain derived
from a tumor-specific monoclonal antibody
single chain variable fragment (scFv)
2. A transmembrane domain anchoring the CAR
to the T cell-derived from CD3, CD4, CD8 or
CD28
3. An intracellular T cell activation domain of
CD3ζ with or without costimulatory molecules
The transmembrane domain connects the scFv,
which specifies the T cell binding to a tumor
antigen to the intracellular CD3ζ domain,
responsible for T cell activation.

22. 3 qualities required by Car-Tcells
• Recognition of Target antigen on tumor cell
• Proliferation in vivo
• Persistence for longer duration

25. • Most of the clinical data we have is from 1st and 2nd generation CAR-T
designs.
• Kymriah™ is a 2nd-generation CAR-T that combines an extracellular
anti-CD19 antibody fragment with costimulatory intracellular
signaling domains, CD3ζ and CD137 (4-1BB).
• CD-19 antigen, which is uniquely expressed on most B cells and B
lymphoid progenitors. CD-19 is also expressed on all tumor cells and
its expression is retained during tumor cell progression.

26. Phase II ELIANA trial
• The first pediatric global CAR-T cell therapy registration trial.
• 25 centers in the US, Canada, European Union, Australia, and Japan.
• The single-arm, open-label, multicenter phase II study.
• patients aged 3 to 23 years who were primary refractory, refractory to
chemotherapy after their first relapse, relapsed after second line therapy,
or ineligible for an allogeneic stem-cell transplant (SCT).
• Patients in the trial received a median of three prior lines of therapy and
59% of patients had a prior SCT.

27. Responses in patients who don’t have much Rx options
except CAR T
• 83% of patients( 52 /63) achieved complete remission (CR) or CR with incomplete blood
count recovery within 3 months of infusion.
• No minimal residual disease (MRD) was detected among responding patients and in
those achieved CR.
• Achieved CR s are durable at 6 months of study.
• the relapse-free probability was 75% at 6 months and 64% at 12 months among
responders.
• In addition, the probability of survival was 89% (95% CI = 77%–94%) at 6 months and
79% (95% CI = 63%–89%) at 12 months.

28. Toxicity in
ELIANA:
• 47% experienced grade 3 or 4 cytokine release
syndrome, a known complication –> managed
cytokine-release syndrome treatment
algorithm.
• No deaths due to refractory cytokine-release
syndrome, and no incidents of cerebral edema
were reported.
• Grade 3 neurologic events were reported in
15% of patients; no grade 4 events were seen.

29. Other side effects
• Hypersensitivity
• B cell aplasia
• Hypogammaglobunemia and infections

30. CYTOKINE RELEASE SYNDROME (CRS)
• The most common side effect of CAR-T cells Not always fatal.
• Results from the activation of a large number of T cells causing the release of inflammatory
cytokines, primarily IFN-γ, IL-6, IL-10, TNF-α and IL-2, several hundred times above baseline.
• This flood of cytokines can cause systemic inflammatory responses, hypotension, fever, and
neurological changes.
• Ironically, CRS is an “on-target”/”off-tumor” effect of the therapy  Indicates the treatment is
working; there are active CAR T cells in the body.
• Tocilizumab (Actemra®), which blocks IL-6 activity, used to treat juvenile arthritis has been found
to mitigate the effects of CRS in patients.

33. Second
approval of
CAR T: first in
adults
• YESCARTA( axicabtagene ciloleucel) is a CD19-
directed genetically modified autologous T cell
immunotherapy.
• Indicated for the treatment of adult patients
with relapsed or refractory large B-cell
lymphoma after two or more lines of systemic
therapy, including DLBCL- NOS, primary
mediastinal large B-cell lymphoma, high grade
B-cell lymphoma, and DLBCL arising from
follicular lymphoma.

34. As a part of trial JCAR017
• a 68-year-old woman with refractory
diffuse large-B-cell lymphoma (DLBCL),
germinal-center subtype, refractory to R-
DAePOCH and 8/8 match AlloSCT. CR
achieved at 1 month after Flu-cy
conditioning CART Therapy

35. Hurdles in CAR T cells in solid cancers…
• One main hurdle is identifying a suitable target that isn’t present cells in healthy tissues.
• Low T-cell infiltration and an immunosuppressive environment prevent the immune
system from effectively attacking solid tumors.
• the latest approach in ACT for solid tumors is the fourth generation of CARs
These T cell redirected for universal cytokine killing or TRUCK T cells are genetically
modified to express CARs along with an inducible cytokine gene cassette.
• Interleukin (IL)-12 cytokine which directly enhances T-cell activity and may help undo
the immunosuppressive tumor microenvironment by triggering the apoptosis of
inhibitory macrophages
• IL-12 cannot be administered systemically due severe toxicities.
• With TRUCKs, IL-12 is only secreted when antigen binding activates the CAR T cell.

36. Everything clear about CAR’s? answer is NO
• Improvements in molecular biology and our understanding of immunology also
highlights the shortcomings in new discoveries.
• In 2016 to Seattle-based Juno Therapeutics one of the early leaders in the CAR-T
field in their phase II ROCKET trial examined JCAR015 (also a CD-19 targeted
therapy) for patients with r/r B cell ALL.
• 5 of 38 adults treated with JCAR015 died unexpectedly from severe neurotoxicity-
triggered cerebral edema (brain swelling).
• A sobering reminder that, despite the utmost safety measures, these therapies
are experimental and not without flaws.
• Unpredictable outcomes are always a risk when dealing with complex biological
systems and patients that have diverse genetic backgrounds.

37. Are the risks worth the
reward?
• The one-time treatment has a high
price tag of $475,000 USD .
• Insurance companies in USA are
reimbursing in qualified patients.

38. Future : appears hopeful !
• CAR T cells that express additional accessory molecules to serve as safety
switches Allows for the elimination of CAR T cells from circulation, in the event
of life threatening T-cell-mediated toxicity―essentially an “off” switch.
• Inactive, monomeric caspase9 subunits expressed in CAR T cells can form a lethal
dimer, causing the rapid clearance of CAR-T cells, when exposed to dimerizing
agent.
• Nearly 76 CAR-T therapies under evaluation by the FDA.
• THINK (THerapeutic Immunotherapy with NKG2D) is a Phase I study of CYAD-01
in seven refractory cancers, including five solid tumors (colorectal, ovarian,
bladder, triple-negative breast and pancreatic cancers) and two hematological
tumors (acute myeloid leukemia and multiple myeloma).