Cancer ImmunologyCancer Immunology

IntroductionIntroduction Ags expressed by cancer cellsAgs expressed by cancer cells Nature of immune responseNature of immune response How cancer evades immune How cancer evades immune

systemsystem ImmunotherapyImmunotherapy

Cancer Introduction

Cancer Introduction

Uncontrolled growth produces a tumor or Uncontrolled growth produces a tumor or neoplasm.neoplasm.

A tumor that grows indefinitely and A tumor that grows indefinitely and spreads (metastasis) is called spreads (metastasis) is called malignantmalignant----also called cancer.also called cancer.

A tumor that is not capable of indefinite A tumor that is not capable of indefinite growth----growth----benign.benign.

Malignant---kills host.Malignant---kills host. Benign---does not kill host.Benign---does not kill host.

Types of CancerTypes of Cancer CarcinomaCarcinoma: Cancer of endo or ectoderm : Cancer of endo or ectoderm

e.g. Skin or epithelial lining of organse.g. Skin or epithelial lining of organs SarcomasSarcomas: Cancer of mesoderm e.g. bone: Cancer of mesoderm e.g. bone Leukemias and LymphomasLeukemias and Lymphomas: Cancers of : Cancers of

hematopoietic cellshematopoietic cells

Cell GrowthCell Growth

Control of cell growth

Growth-promotingProto-oncogenes

Growth-restrictingTumor-suppressor genes

Molecular Basis of CancerMolecular Basis of Cancer

Uncontrolled cell growth

Proto-oncogenesTumor-suppressor genes

MutationsRadiationChemicalsVirus

Do tumors express foreign Ags?Do tumors express foreign Ags?

Transfertumor

H-2kH-2b

Rejects tumor

SummarySummary

When a tumor from H-2When a tumor from H-2k k mouse was mouse was injected into H-2injected into H-2bb mouse, it was rejected. mouse, it was rejected.

This experiment does not demonstrate This experiment does not demonstrate immunity against cancer.immunity against cancer.

Tumor was rejected due to expression of Tumor was rejected due to expression of foreign MHCforeign MHC

Syngeneic(accepted)

Allogeneic(rejected)

Inbred: repeated brother-sister matings

Outbred:normal population

Xenogeneic(rejected)

Ags expressed on tumor cellsAgs expressed on tumor cellsMajor HistocompatabilityComplex antigens

TAVA

TSTA

TADA

TSTA: unique to a tumor plays an important role in tumor rejection.

Tumor-specific transplantation AgTumor associateddevelopmental Ag

Tumor associated viral Ag

Demonstration of TSTADemonstration of TSTA

Induce tumors with chemicals (carcinogens) e.g. methylcholanthrene, benzopyrene

No tumor growth

control

tumor grows

Remove tumor, irradiate andinject into syngeneicmice

Inject viable tumor cells into normal or immunized mice

Immunized mouse

SummarySummary

Mice immunized with Mice immunized with syngeneicsyngeneic irradiated irradiated tumor cells could reject the same live tumor cells could reject the same live tumor upon rechallenge.tumor upon rechallenge.

However, an unimmunized mouse However, an unimmunized mouse developed tumor and died.developed tumor and died.

Because this experiment was done in a Because this experiment was done in a syngeneic mouse, tumors express TSTA.syngeneic mouse, tumors express TSTA.

Chemically induced cancers Chemically induced cancers

Each tumor induced by a carcinogen Each tumor induced by a carcinogen expresses a unique Ag.expresses a unique Ag.

Thus difficult to develop vaccine.Thus difficult to develop vaccine.

Tumor-Associated Developmental AgsTumor-Associated Developmental Ags

Found on cancer cells and on fetal cells.Found on cancer cells and on fetal cells. Do not trigger anti-tumor immunity.Do not trigger anti-tumor immunity. Used in diagnosis.Used in diagnosis. Alpha-fetoprotein(AFP) Cancers of Alpha-fetoprotein(AFP) Cancers of

liverliver Carcinoembryonic Ag (CEA) colorectal Carcinoembryonic Ag (CEA) colorectal

cancercancer

Other Tumor associated antigensOther Tumor associated antigens Silent gene-encoded Ags e.g. Thymic leukemic antigen Silent gene-encoded Ags e.g. Thymic leukemic antigen

(Tla) expressed in thymocytes of some strains(Tla) expressed in thymocytes of some strains Differentiation Ags: B cells produce surface Ig. Differentiation Ags: B cells produce surface Ig.

B cell tumors have sIgB cell tumors have sIg

Melanomas and melanocytes express MART-1Melanomas and melanocytes express MART-1 Overexpression of Ag on tumors compared to normal Overexpression of Ag on tumors compared to normal

cells e.g. In Breast cancer, HER2/neu homologous to cells e.g. In Breast cancer, HER2/neu homologous to Epidermal Growth Factor Receptor (EGFR)Epidermal Growth Factor Receptor (EGFR)

Abnormal posttranslational modifications. Abnormal posttranslational modifications. Underglycosylated mucin (MUC-1) e.g. breast cancerUnderglycosylated mucin (MUC-1) e.g. breast cancer

Ags expressed on male germ cells (lack MHC) and Ags expressed on male germ cells (lack MHC) and melanoma e.g. MAGE-1melanoma e.g. MAGE-1

Virally induced tumorsVirally induced tumors

Types:Types: DNA viruses: papova (SV40, polyoma, DNA viruses: papova (SV40, polyoma,

papilloma), hepatitis, adenovirus.papilloma), hepatitis, adenovirus. RNA viruses: Retroviruses---> Human T-RNA viruses: Retroviruses---> Human T-

lymphotropic viruses (HTLV-I and lymphotropic viruses (HTLV-I and HTLV-II).HTLV-II).

Induce a strong immune response.Induce a strong immune response.

Feline leukemia

Latentor recovered

Oncogenic disease

Non-oncogenic disease

Feline leukemia VirusFeline leukemia Virus Transmitted from cat to cat through saliva Transmitted from cat to cat through saliva

or transplacentallyor transplacentally Cats produce virus neutralizing Abs and Cats produce virus neutralizing Abs and

/or anti-tumor Abs/or anti-tumor Abs If both Abs are produced, cats recover.If both Abs are produced, cats recover. If only anti-tumor Abs are produced, they If only anti-tumor Abs are produced, they

get non-oncogenic disease.get non-oncogenic disease. If both Abs are not produced, cats get If both Abs are not produced, cats get

oncogenic disease.oncogenic disease.

UV-induced tumorsUV-induced tumors

>800,000 cases of skin cancer/year.>800,000 cases of skin cancer/year. UV radiation--->most serious skin UV radiation--->most serious skin

cancer--->melanomascancer--->melanomas Highly immunogenic.Highly immunogenic.

SummarySummary

A tumor grows in syngeneic host but not A tumor grows in syngeneic host but not in allogeneic or xenogeneic hostsin allogeneic or xenogeneic hosts

Tumor Ags expressed may be specific to Tumor Ags expressed may be specific to a tumor cell or shared with other cellsa tumor cell or shared with other cells

Evidence for the role of immune system in tumor rejection

Evidence for the role of immune system in tumor rejection

Spontaneous regressionSpontaneous regression Regression of metastases after removal of Regression of metastases after removal of

primary tumorprimary tumor Regression after chemotherapyRegression after chemotherapy Infiltration of tumors by lymphocytes and Infiltration of tumors by lymphocytes and

macrophagesmacrophages Lymphocyte proliferation in draining lymph Lymphocyte proliferation in draining lymph

nodesnodes Higher incidence of cancer after Higher incidence of cancer after

immunosuppression, immunodeficiency immunosuppression, immunodeficiency (AIDS, neonates), aging, etc.(AIDS, neonates), aging, etc.

Requirements for effective immune response against tumors

Requirements for effective immune response against tumors

Tumor should express a foreign Ag.Tumor should express a foreign Ag. Tumor should be immunogenic.Tumor should be immunogenic. Host should be immunocompetent.Host should be immunocompetent. Immune response should not result in Immune response should not result in

tolerance.tolerance. Tumor should not change Ag.Tumor should not change Ag.

Immunity against tumorsImmunity against tumors

tumormacrophage

T helper (Th) cell

B cell

tumor

CTL

tumor AgClass I MHC

NK

FasL Fas

CTL Tumor

Perforin/granzyme

NK

Apoptosis

T lymphocytesT lymphocytes

CD4 CD8

T helper T cytotoxic

Tumor Tumor

ClassI MHCClassII MHC

AgAg

Produce factors that activate other cells to kill tumor cells Directly kill Cl II+ tumor cells

Lyse tumor cells

T cell receptor (TCR)

Role of CTLRole of CTL

TSTA is processed and presented with TSTA is processed and presented with Class I MHC to CTLClass I MHC to CTL

CTL produce FasL or perforin/granzyme CTL produce FasL or perforin/granzyme which kills the tumor cell. which kills the tumor cell.

If tumor cells are Fas+ve, CTL will use If tumor cells are Fas+ve, CTL will use FasL to kill tumor cell apoptosis.FasL to kill tumor cell apoptosis.

Role of Th cellsRole of Th cells TSTA shed by cancer cells, is processed and TSTA shed by cancer cells, is processed and

presented by B cells or macrophages to Th presented by B cells or macrophages to Th cellscells

Th cells will activate B cells or macrophages Th cells will activate B cells or macrophages by producing cytokines.by producing cytokines.

Abs are not very effective against cancer Abs are not very effective against cancer except against retrovirally induced tumors.except against retrovirally induced tumors.

Activated macrophages can kill the tumor Activated macrophages can kill the tumor cells.cells.

B Lymphocytes B Lymphocytes

sIg

Tumor

Complement

Natural Killer cell/Macrophage/Granulocyte

FcRFabFc

Tumor

Ab dependent cell cytotoxicity(ADCC)

Ag

Role of NK cellsRole of NK cells NK cells can recognize MHC -ve tumor NK cells can recognize MHC -ve tumor NK cells are large granular lymphocytes NK cells are large granular lymphocytes

(LGL) TCR(LGL) TCR--, asialoGM, asialoGM++ or NK1.1 or NK1.1++.. It is not known exactly how NK cells It is not known exactly how NK cells

recognize tumor cells.recognize tumor cells. Lyse virally-infected cells and tumor cellsLyse virally-infected cells and tumor cells Spontaneous cytotoxicity/ADCCSpontaneous cytotoxicity/ADCC Activity increased by interleukin (IL)-2 = Activity increased by interleukin (IL)-2 =

lymphokine-activated killer cells (LAK)lymphokine-activated killer cells (LAK) They use FasL and perforin to kill tumor They use FasL and perforin to kill tumor

cells.cells.

MacrophagesMacrophages Normal MNormal M not tumoricidal not tumoricidal Activated MActivated Mare tumoricidalare tumoricidal Direct cytotoxicity or ADCCDirect cytotoxicity or ADCC Reactive oxygen intermediates (OReactive oxygen intermediates (O--, H, H22OO22))

Nitric oxide (NO)Nitric oxide (NO) Tumor necrosis factor (TNF)Tumor necrosis factor (TNF) Lysosomal enzymes Lysosomal enzymes Antigen processing and presentationAntigen processing and presentation

How does a tumor escape immune recognition?How does a tumor escape immune recognition?

Generation of suppressor cellsGeneration of suppressor cells Secrete immunosuppressive molecules Secrete immunosuppressive molecules

Ex: prostaglandins, transforming growth Ex: prostaglandins, transforming growth factor beta (TGF-factor beta (TGF-), IL-10, etc.), IL-10, etc.

Tumor T regulatory

MCTL

Tumors may fail to process and present Tumors may fail to process and present Ag.Ag.

Downregulation of MHC expression on Downregulation of MHC expression on tumor cell (CTL resistant but NK tumor cell (CTL resistant but NK sensitive)sensitive)

Tumors may fail to express Tumors may fail to express adhesion/costimulatory molecules adhesion/costimulatory molecules involved in T cell activation.involved in T cell activation.

Tumors escape the action of CTL by not expressing B7 molecule involved in T cell activation

tumor

CTL

tumor Ag

Class I MHC

B7

CD28

Tumor escape mechanisms:Tumor escape mechanisms:Fas FasL

TumorCTL

FasFasL

TumorCTL

When tumor cells express Fas Ligand,they can kill Fas+T cells, thereby escapingimmune destruction.

Ag masking: sialic acid, mucin, fibrin coating

Tolerance of host to tumor Ags - Tolerance of host to tumor Ags - Neonatal exposure e.g. murine mammary Neonatal exposure e.g. murine mammary tumor virustumor virus

Tolerogenic Ags of tumor (high dose/low Tolerogenic Ags of tumor (high dose/low dose or no costimulators)dose or no costimulators)

Tumor

Mutation in tumor cells with loss of Mutation in tumor cells with loss of antigen expressionantigen expression

Antigenic modulationAntigenic modulation: Ab binding leads : Ab binding leads to endocytosis or shedding of Ag-Ab to endocytosis or shedding of Ag-Ab complexes.complexes.

Blocking FactorsBlocking Factors: Shed Ag or Ag-Ab : Shed Ag or Ag-Ab complexes act as blocking factors . Block complexes act as blocking factors . Block FcR of NK or induce suppressor cellsFcR of NK or induce suppressor cells

Cancer TherapyCancer Therapy Surgery - Surgery -

Localized tumorsLocalized tumors Radiation - Radiation -

Metastastic tumorsMetastastic tumors Affects proliferating cells (bone marrow, etc.) Affects proliferating cells (bone marrow, etc.) Radiation-resistant tumors developRadiation-resistant tumors develop

Chemotherapy - Chemotherapy - Metastastic tumorsMetastastic tumors Affects proliferating cells (bone marrow, etc.) Affects proliferating cells (bone marrow, etc.) Drug-resistant tumors developDrug-resistant tumors develop

Immunotherapy -Immunotherapy - Metastastic tumorsMetastastic tumors SpecificitySpecificity Do not develop resistanceDo not develop resistance No toxicityNo toxicity

ImmunotherapyImmunotherapy Active ImmunizationActive Immunization: :

SpecificSpecific Vaccination with viral Ags: e.g.Vaccination with viral Ags: e.g.

Feline leukemia virus (FLV)Feline leukemia virus (FLV)Herpes - Marek’s disease of chickens Herpes - Marek’s disease of chickens Hepatitis B virus.Hepatitis B virus.

Haptenated tumor cells (trinitrophenol - Haptenated tumor cells (trinitrophenol - TNP)TNP)

Costimulator (B7) transfected tumor cellsCostimulator (B7) transfected tumor cells

tumorCTL

CD28

Tumors escape the action of CTL by not expressing B7 molecule

tumor

B7 CD28

CTL

No killing

killing

Use of B7 to induce anti-tumor immunity

B7-ve tumorDies

SurvivesB7+ve tumor

tumor

Use of MAGE as a vaccine against melanomasUse of MAGE as a vaccine against melanomas

Expressed on normal melanocytes and Expressed on normal melanocytes and melanomas – Vitiligo (skin depigmentation)melanomas – Vitiligo (skin depigmentation)

MAGE

NonspecificNonspecific:: BCG (Bacillus Calmette-Guerin) BCG (Bacillus Calmette-Guerin)

Mycobacteria - melanoma, bladder Mycobacteria - melanoma, bladder carcinomacarcinoma

Corynebacterium parvum (C. parvum)Corynebacterium parvum (C. parvum) Muramyl dipeptideMuramyl dipeptide

Normal M

Tumor

Activated M

Tumor lysis

Anti-CD3 Abs - polyclonal activation of T Anti-CD3 Abs - polyclonal activation of T cellscells

CD3

TCR

TumorT cell T cell Tumor

CD3

TCR

Tumor Ag

MHCMHC

Tumor Ag

Anti-CD3T cell Activation

Passive ImmunizationPassive Immunization Specific:Specific: Ab Therapy Ab Therapy

Anti-idiotypic AbsAnti-idiotypic Abs

Abs against growth factor receptor e.g. IL-2R Abs against growth factor receptor e.g. IL-2R in HTLV-1 induced Adult T cell leukemiain HTLV-1 induced Adult T cell leukemia

Abs specific for oncogene product e.g. Abs Abs specific for oncogene product e.g. Abs against HER2/against HER2/neu (neu (Herceptin or trastuzumab)Herceptin or trastuzumab)

B celltumor

Idiotype

B cell

IL-2R

IL-2

Anti-IL-2R

Monoclonal Abs used in Immunotherapy

Monoclonal Abs used in Immunotherapy

Unlabelled Ab: e.g. Anti-CD20 Ab in Unlabelled Ab: e.g. Anti-CD20 Ab in non-Hodgkin’s lymphoma non-Hodgkin’s lymphoma

C’C’ ADCCADCC

Labelled Ab (Radioisotope/Toxin)Labelled Ab (Radioisotope/Toxin) 131131I (Iodine)I (Iodine) InternalizationInternalization

Anti-tumor Abs coupled to toxin, Anti-tumor Abs coupled to toxin, radioisotopes, drugs or enzymesradioisotopes, drugs or enzymes::

ImmunotoxinsImmunotoxins: : Ricin A/diphtheria/Pseudomonas Ricin A/diphtheria/Pseudomonas toxin coupled to Abs. e.g. antiCD22-toxin coupled to Abs. e.g. antiCD22-Psudomonas toxin in hairy (B) cell Psudomonas toxin in hairy (B) cell leukemia leukemia Toxin inhibits protein synthesis.Toxin inhibits protein synthesis.Cytocidal isotopes or anticancer Cytocidal isotopes or anticancer drugs (adriamycin) coupled to Absdrugs (adriamycin) coupled to Abs

TumorRicin

ProdrugDrug

Ab-Enzyme

Inefficacy of Abs Tumor Ags + Class I MHCTumor Ags + Class I MHC Shedding/internalization of tumor Ag/Ag-Ab Shedding/internalization of tumor Ag/Ag-Ab

complexescomplexes Noncytotoxic Abs (C’/ADCC) Noncytotoxic Abs (C’/ADCC) Anti-rat/mouse Ab develops causing Anti-rat/mouse Ab develops causing

anaphylaxis and serum sicknessanaphylaxis and serum sickness ––Humanized/chimeric Ab (from 2 species)Humanized/chimeric Ab (from 2 species)

Human Fc

Mouse Fab

T cell Tumorcell

CD3Ag

Bispecific Ab Humanized Ab

Half life of AbHalf life of Ab Non specific binding to FcR+ cells (MNon specific binding to FcR+ cells (M, ,

granulocytes, NK and B cells)granulocytes, NK and B cells)

M

Adoptive Immunotherapy

1. 1. Lymphokine-activated killer cells Lymphokine-activated killer cells (LAK): (LAK): PBL + high dose IL-2PBL + high dose IL-2

NKNK LAKLAK

2. 2. Tumor-infiltrating lymphocytes Tumor-infiltrating lymphocytes (TIL): (TIL):

In and around solid tumorsIn and around solid tumors

Activated NK and CTLActivated NK and CTL

1)Use of LAK cells + IL-2 to treat cancer1)Use of LAK cells + IL-2 to treat cancer

Isolate lymphocytes from blood

lymphocytes

+IL-2 for 3 days

IL-2

LAKcells

melanoma

Immunotherapy of CancerImmunotherapy of Cancer

Treatment of Melanoma with LAK cells +IL-2

Treatment of Melanoma with LAK cells +IL-2

Before After

2) Use of tumor-infiltrating lymphocytes + IL-2 to treat cancer2) Use of tumor-infiltrating lymphocytes + IL-2 to treat cancer

surgical removalof cancer nodule

tumor

T cell

+IL-2

IL-2

Successful treatment of melanoma and renal cell carcinoma

Treatment of Melanomas with TIL + IL-2

Treatment of Melanomas with TIL + IL-2

Before After

Problems associated with IL-2 therapy

Problems associated with IL-2 therapy

Very toxic----triggers vascular leak.Very toxic----triggers vascular leak.

IL-2

T cell

CD44

endothelial cells

Dendritic CellsDendritic Cells Highly potent antigen processing and Highly potent antigen processing and

presenting cellspresenting cells Prime an Immune ResponsePrime an Immune Response Pulse with tumor Ags or gene transferPulse with tumor Ags or gene transfer

Cl II Cl I

Autologous bone marrow (treated Autologous bone marrow (treated in vitro in vitro with Ab + C) transplantation following with Ab + C) transplantation following irradiation.irradiation.

Allogeneic bone marrow transplantation Allogeneic bone marrow transplantation (matching 1 or 2 HLA Ag) – Graft versus (matching 1 or 2 HLA Ag) – Graft versus host reactionhost reaction

Cytokine Therapy

Inj. cytokines.Inj. cytokines.

1.1. Interleukin -2 (IL-2) high dose - Alone Interleukin -2 (IL-2) high dose - Alone or or with cellswith cells

Melanoma and renal cell carcinomaMelanoma and renal cell carcinoma

Activates NK and CTLActivates NK and CTL

Toxic - fever, edema, shockToxic - fever, edema, shock

IL-4IL-4

2.2. Tumor necrosis factor (TNF) - Tumor necrosis factor (TNF) - CarcinomaCarcinoma

3.3. Interferon (IFN)-Interferon (IFN)- Produced by Leukocytes Produced by Leukocytes

Activates NK activityActivates NK activity

Increases class I MHCIncreases class I MHC

Hairy cell leukemia, renal cell carcinoma, Hairy cell leukemia, renal cell carcinoma, melanoma, Kaposi sarcoma, hematologic melanoma, Kaposi sarcoma, hematologic cancerscancers

4.4. IFN-IFN- : Ovarian carcinoma : Ovarian carcinoma

5.5. Hematopoietic growth factors: Hematopoietic growth factors: Overcome neutropeniaOvercome neutropenia

Granulocyte-macrophage colony stimulating Granulocyte-macrophage colony stimulating factor (GM-CSF)factor (GM-CSF)

Granulocyte colony stimulating factor Granulocyte colony stimulating factor

(G-CSF)(G-CSF)

Gene therapyGene therapyIntroduce cytokine genes for IL-2, IL-4, IL-12,GM-CSF or IFN-into tumor cells.

Tumor Ag gene expressed in DC (Tumor Ag Tumor Ag gene expressed in DC (Tumor Ag usually not known).usually not known).

tumorT cell

M

IL-2IL-4

GM-CSF

SUMMARYSUMMARY

Tumors should express TSTA.Tumors should express TSTA. T cells are important in tumor rejection.T cells are important in tumor rejection. NK cells and macrophages also play an NK cells and macrophages also play an

important role.important role. Tumors evade immune system in a Tumors evade immune system in a

number of ways.number of ways. Immunotherapy is promising.Immunotherapy is promising.

Immunotherapy of CancerImmunotherapy of Cancer Manipulation of the host’s immune system to Manipulation of the host’s immune system to

treat cancer.treat cancer. Treatment with IL-2---to activate NK/LAK Treatment with IL-2---to activate NK/LAK

cells.cells. Culture and transfer of tumor infiltrating Culture and transfer of tumor infiltrating

lymphocytes.lymphocytes. ImmunotoxinsImmunotoxins Cytokine gene-therapyCytokine gene-therapy Dendritic cell therapyDendritic cell therapy Bone marrow transplantationBone marrow transplantation Anti -idiotypic Abs against myelomas.Anti -idiotypic Abs against myelomas.

Suggested ReadingSuggested Reading

Immunobiology: The Immune System in Immunobiology: The Immune System in Health and Disease by Janeway et al. 6Health and Disease by Janeway et al. 6 thth edition, 2005. Pg. 630-642edition, 2005. Pg. 630-642