2. Cancer from an Immune Perspective
Cancers are not infectious agents and therefore lack the
molecular signatures that normally enable the immune
system to recognize and react. This appears to be the root
of the problem.
This is not to say that tumors are invisible to the immune
system. Tumors are frequently heavily infiltrated by
macrophages and neutrophils. But such cells are often
actively recruited by the tumor and can promote tumor
proliferation, angiogenesis, and progression through the
production of inflammatory mediators and reactive oxygen
or nitrogen species that provoke DNA damage and thus
additional mutations.
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Sample & Assay Technologies
3. Cancer Immunoediting
Strongly immunogenic tumors would fail to develop to the
point that they become clinically significant. In this way, the
immune system may exert a selective pressure for cancercausing mutations (such as ras point mutation, complete loss
of p53 or Rb) that are largely immunologically silent – a
process that is termed immunoediting.
.
In other words, immunoediting is a process ranging from
immune surveillance to immune escape. It’s an immune
selection.
.
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Sample & Assay Technologies
4. Cancer Immunoediting – 3E Theory
.
.
Phase 1: Recognition, infiltrating, recruiting
Phase 2: Induce tumor death
Elimination
.
Phase 3: Promote more tumor death
Phase 4: Destroy all tumor cells
Equilibrium: Tumor cells which have survived the elimination phase enter
the equilibrium phase.
.
Escape: Tumor cells which have acquired resistance to equilibrium enter
the escape phase.
.
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6. Tumor Escape Mechanisms – Immunosuppression
.
Tumor-Derived Soluble Factors
Tumor cells produce immunosuppressive factors:
.
IL-10, TGF-β, VEGF, Prostaglandins, etc.
.
.
Cellular Components:
Regulatory T cells (Tregs), Myeloid-derived suppressor cells (MDSCs) and
invariant Natural Killer T cells (iNKTs).
.
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Sample & Assay Technologies
7. How do Cancer Cells Become Resistant to Elimination?
Paper 1:
We demonstrate that the strong immunogenicity of an
unedited tumor can be ascribed to expression of highly
antigenic mutant proteins. Outgrowth of tumor cells that lack
these strong antigens through a T-cell-dependent
immunoselection process represents one mechanism of
cancer immunoediting (Nature, Feb 2012).
.
.
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Sample & Assay Technologies
8. How do Cancer Cells Become Resistant to Elimination?
Paper 2:
By comparing the development of tumors in immunecompetent mice to that in mice with broad immunodeficiency
or specific antigenic tolerance, we show that recognition of
tumor-specific-antigens by lymphocytes is critical for
immunoediting. Furthermore, primary sarcomas were edited to
become less immunogenic through the selective outgrowth of
cells that were able to escape T cell attack. Loss of tumor
antigen expression or presentation on MHC (Major
Histocompatibility Complex) class I was necessary and
sufficient for this immunoediting process to occur. These
results highlight the importance of tumor-specific-antigen
expression in immune surveillance, and potentially,
immunotherapy (Nature, Feb 2012).
.
.
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9. Conclusion
T cell recognition of tumor antigens is key to cancer immunoediting.
The Clinical Case of Cancer Immunoediting:
Most glioblastoma at relapse are negative for EGFRvIII expression,
a relevant and direct example of cancer immunoediting (Expert Rev
Anticancer Ther, Nov 2011).
.
.
.
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Sample & Assay Technologies
10. The Induction of Anti-Cancer Immunity
1. Tumor cells express tumor-associated antigens on MHC
class I.
.
2. Cytotoxic T cells recognize tumor-associated antigens and
kill tumor cells.
.
3. Dendritic cells (DCs), which are important antigen
presenting cells (APCs), take up and process antigen from
dead or dying tumor cells, present the tumor-associated
antigens on MHC class I and II and stimulate T cells and other
immune cells.
.
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Sample & Assay Technologies
12. Anti-Cancer Immunotherapies
2. Immune Checkpoint Blockade
Block CTLA4-B7 and PD1-PDL1 interactions –
The CTLA4-blocking antibody ipilimumab (Bristol-Myers Squibb)
has been approved by FDA for treating melanoma in March 2011.
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Sample & Assay Technologies
13. Anti-Cancer Immunotherapies
.
3. Adoptive Cell Transfer
Two main approaches are being explored:
.
* T cells that reside in the tumor are cultured and expanded ex vivo in
the presence of IL-2. When enough of these polyclonal T cells are
obtained, they are re-infused into the patient.
.
* Isolated peripheral blood T cells are transfected to express tumorantigen-specific TCRs (T Cell Receptors) and then re-administered to
the patient. This strategy has the advantage that enough T cells can
be obtained for infusion in all patients, but a potential drawback is
that the TCRs that are transfected into the T cells have a limited
antigen-specificity repertoire.
.
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Sample & Assay Technologies
14. Anti-Cancer Immunotherapies
.
4. Cellular Vaccines
* Tumor cell or tumor antigen vaccination
Extracted, irradiated tumor cells are re-administered to the patient. Adjuvants
such as TLR agonists or GM-CSF are required.
.
.
* APC vaccination
APCs are extracted from a patient’s bloodstream, cultured and activated with
cytokines or adjuvants, loaded with tumor antigen ex vivo, and re-administered to
the patient. Sipuleucel-T (made by Dendreon) has been approved by FDA for
prostate cancer treatment in April 2010.
.
.
* DC vaccination
DCs are cultured from peripheral blood monocytes in the presence of IL-4 and
GM-CSF, and activated and loaded with tumor antigen ex vivo, and readministered to the patient.
.
.
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Sample & Assay Technologies
15. Inflammasomes and Anti-Cancer Immunity
Inflammasomes in carcinogenesis and anticancer immune responses
.
Nature Immunology 13, 343-351, 2012 (March 18, 2012)
.
The inhibition of inflammasomes or neutralization of their products, mainly interleukin 1β (IL1β) and IL-18, has profound effects on carcinogenesis and tumor progression.
.
---------------------------------------------------------------------------------------------------------------------------
.
Inflammasomes PCR Arrays
.
http://www.sabiosciences.com/rt_pcr_product/HTML/PAHS-097Z.html
.
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Sample & Assay Technologies
16. Profiling Gene Expressions –
Using RT2 Profiler PCR Array
84 Pathway-Specific
Genes of Interest
5 Housekeeping Genes
Genomic DNA
Contamination Control
Reverse Transcription
Controls (RTC) n=3
Positive PCR Controls
(PPC) n=3
http://www.sabiosciences.com/rt_pcr_product/HTML/PAHS-011Z.html
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Sample & Assay Technologies
17. PCR Array Work Flow
cDNA Synthesis (kit)
45 minutes
Load Plates (Use 8-Channel
Pipettors)
2 minutes
Run 40 cycle qPCR Program
2 to 2.5 hours
compatible with all major
real-time PCR instruments
Upload and Analyze Data
15 minutes
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Sample & Assay Technologies
27. Next Generation Sequencing (NGS)
Why spend time sequencing the entire genome when your research
is focused on a few genes?
QIAGEN now offers GeneRead DNAseq Gene Panels, with which you can
analyze genetic variants among specific genes of your interest or pre-selected,
cancer-focused gene panels. These panels, each with a small number of
thoroughly researched genes, enable:
• Deep sequencing
• Identification of low-frequency genetic variants
• Savings in time, money and sample usage
GeneRead DNAseq Gene Panels use multiplex PCR target enrichment
technology based on sophisticated primer design and pooling algorithms.
The PCR primer sets cover the protein-coding regions and untranslated regions
(UTRs) of all human genes. Each panel includes integrated controls to identify
poor-quality samples / libraries before sequencing.
http://www.sabiosciences.com/NGS.php
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Sample & Assay Technologies
28. Next Generation Sequencing (NGS)
• Comprehensive Cancer
• Breast Cancer
• Colon Cancer
• Prostate Cancer
• Lung Cancer
• Liver Cancer
• Ovarian Cancer
• Gastric Cancer
• Leukemia
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Sample & Assay Technologies