Tumor immunologyImmune erosion

100 60 10 0yr Cancer/ Infection/ Neuronal disorder Development

Expected life-span

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Evidence for active host defense against cancer

80 years of immunotherapy. (Currie

GA, 1972, Br. J. Cancer 26: 141)

A critique of the evidence for active host defense against cancer, based on personal studies of 27 murine tumors of spontaneous origin. (Hewitt HB, et al.

1976, Br. J. Cancer 33:241)

Anti-tumor immunity

Circulating tumor antibodies

Tumor infiltrating lymphocytes: CTL expansion and autologous tumor lysis.

MHC-I down-regulation

Circumvent evidence

A fight between immune cells and cancer

But, sometimes we lose

The great escape:

immune evasion

versus tumor

progression

Immune selection in the development of cancer: no two tumors are alike

Initiation, proliferation diversification

Microevolution, selection of immune resistance

Immune escape and unchecked proliferation

Fey MF & Tobler A 1996

Use of tumor cell lines

Commonly derived from advanced tumors

Retain the genetic instability and lose the ability of adaptations

introduced in large numbers (more than 106 cells)

Tumor formation of Ras-over-expression cells in BALB/c

A dynamic process

Mechanisms of tumor escape

Resistance to killing Antigen-specific

mechanisms (Treg?) Down-regulation of

the class I presentation pathway

Global mechanisms

Tumor and activated T cells

Two major pathways for TCL: Fas-mediated and perforrin-mediated

Resistance to killing

Defective Fas pathway Resistance to Granzyme B

Fas-L and Neutrophil

Cytotoxic T cells

Innate immunity

Fas signal

Loss sensitivity to Fas-mediated apoptosis

FLICE-like inhibitory proteins Bcl-2, Bcl-XL defected sphingomyelinase

activation (ceramide) decoy receptor 3 (DcR3), soluble

Fas

Fas-L+-melanoma cells are relatively resistant to killing of neutrophils

B16F10

Chen YL, et al J. Immunol. 171:1183-1192.

Antigen-specific mechanisms

Tumor antigen-loss variants

Tolerance

Loss of the melanoma tumor-associated antigen in patients with recurrent metastatic melanoma (J Clin Invest 1996, 98:1633)

B cell tumors expressing class II induced a rapid tolerance of cognate CD4 T cell carrying a transgenic TCR. (PNAS, 1998, 95:1178)

Tumor associated antigens

Tumor-specific shared antigens: restricted in expression to tumors and immune privilege sites.

Tissue-specific differentiation antigens: tyrosinase. (melanoma)

Tumor-specific antigens: mutated, tranlocated genes.

Ubiquitous antigens with over-expression in tumors.

Rosenberg SA. 1999, Immunity 10:281

HLA class I molecules

Antigen presentation for T cells

Inhibitory signals for NK cells

Tumor escape from T cells Immunotherapy with

peptide

Down regulation of the MHC class presentation pathway

Downregulation of MHC class I expression is frequently seen in human tumors.

Loss of MHC-I as a mechanism for tumor escape from CTL-mediated elimination (longitudinal study of melanoma patients)

Five major HLA altered phenotypes found in tumor tissues (Human Immunol. 2000, 61:65)

The five altered phenotypesThe five altered phenotypes

Normal A1A2B8B35Cw7Cw4

1. Total loss - 2. Haplotype loss A1B8Cw7

3. Locus loss A1A2B8B35

4. Allelic loss A2B8B35Cw7Cw4

5. Compound phenotype A1

(Human Immunol. 2000, 61:65)

Global Mechanisms

TGF-beta IL-10 Growth in immune privilege

sites Mucin production: interfering

intercellular adhesion Fas-L? (Fas counterattack) Extracellular matrix?

TGF- signaling in tumor signaling and cancer progression

IL-10 (Th3 or Treg)

Tumors or other cells in environments

Mediation of Enhanced Transcription of the IL-10 Gene in T Cells, Upon Contact with Human Glioma Cells, by Fas Signaling Through a Protein Kinase A-Independent Pathway1

J Immunol, 2003, 171: 3947–3954.

Jurkat and Molt-4 cells were cultured alone (lane 1) or in the presence of U118(V), U118(R), U373(V), or U373(R) (lanes 2, 3, 4, and 5, respectively) for 24 h.

Jurkat T cells

5.3 5.5 6.4

40.5

30.0

50.9

25.4

48.8

26.525.4

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Ap

op

tosi

s (%

)

transwell

How can tumor cells highjack immune cells?

J Immunol. In revision, 2007

Immune therapy

Recombinant and synthetic vaccination Cytokine treatments (IL-2; GM-CSF;

IFN) Cellular therapy with tumor-specific CTL Engineered macrophages Antigen-pulsed macrophages or dendritic

cells

Peptide epitopes for melanoma

Nicholaas P, et al. 1999, Curr Opin Oncol 11:50

DC generated from the PBMC of healthy individuals or from cancer patients transfected with CEA mRNA stimulate a potent CD8+ CTL response in vitro. RNA encoding a chimeric CEA/LAMP-1 lysosomal targeting signal enhances the induction of CEA-specific CD4+ T cells in vivo.

Nair SK, et al. 1998, Nature Biotech 16:364

A FasL mystery

1. Tissue dependant2. Reverse signaling?3. Other than death-triggering

In vivo consequences of Fas-L expression by tumors

(using over-expression system)

Renca, MH134, L5178Y, B16-BL6, CT26*

Note: *:syngenic, nude, SCID #: allogenic, lpr

Ref: Lejeune FJ et al., 1998, Curr. Op. Immunol.

Enhanced rejection Delayed rejection

CT26#B16-F10

Distinct structure of tumor mass

Glioma in Nude mice

May be Fas-L associated?

Why TIL in particular sites?

Penetration of tumor by immune cells

Fas-LR

Control

B16-F10 (melanoma) in B6 mice

Control Fas-LRibozyme

Vector controls Fas-L-ribozyme

Depletion of CD4, CD8 T cells and PMNs affected subcutaneous tumor formation

Granulocytes mediates the Fas-L-associated apoptosis during lung metastasis of melanoma that determines the metastatic behavior (B16F10 in C57BL/6)

Br J Cancer, 87: 359 (2002)

Depletion of CD4, CD8 T cells and PMNs affected lung metastasis

4410

41 357 95154

Vector controls Fas-Lribozyme

What happened here?

Fas

Fas-LImmune cells

Tumor

Tissue environment ?

Cytokines ?

What will happen when Fas-stimulated immune cells resist to die?

Shimon Sakaguchi (2000) Regulatory T Cells Key Controllers of Immunologic Self-Tolerance Cell 101: 455-458

Regulatory T cells: the third man

Alternative paradigm

A tumor is a local growth of abnormal tissue consisting of genetic-altered transformed cells and a number of other cell types and connective tissue components characteristic of each tumor type.

No host, as a tissue, no fighting.

Seljelid R et al 1999, Anticancer Res 19:4809

Complex three-way interactions between tumor cells, their microenvironment and the immune system.

Nature Med.1999,874-875

Tumor Stroma

Fibroblasts Macrophages lymphoid cells (T, B, granulocytes, NK cells) mast cells endothelium intercellular substance; extracellular matrix

A

B

C

A. tumor as abnormal growth of transformed cells.

B. Tumor as malignant tissue.

C. Tumor hijacks macrophage to direct growth.

Black squares: tumor cells; Round: lymphocytes; Oval: macrophages; small circles: mast cells

Seljelid R. 1997, Scan J Immunol 46:437