Tumor Immunology

Xue-Feng Bai, MD, Ph.D.Division of Cancer Immunology

Department of PathologyThe Ohio State University

Email: Xue-Feng.Bai@osumc.edu

Reference

• The basic science of oncologyChapter 20: Cancer and immune systemChapter 21: Biological therapy of cancer

• Science, 2002, 298:850

• J Clin. Invest. 2003, 111: 1487

Important features of the immune system

• Innate immunity & adaptive immunity

• Response to foreign antigens

• Self tolerance

• Immunological memory

Players of the Immune system-Cells that mediate innate

immunity

Players of the immune system-Cells that mediate adaptive immunity

Key molecules involved in immune response

1. T cell receptor

2. MHC molecules

3. Co-stimulatory molecules

4. Effector molecules

T cell receptor (TCR)

MHC molecules

Figure 5-11

Figure 5-13MHC polymorphism

The Function of MHC-Antigen Presentation

Figure 5-17

T cell activation-Two signals required

T cell development in the Thymus

Positive & Negative selection of T cells-Central tolerance

Peripheral T cell tolerance

Questions in tumor immunology

1. Does immune system play a role in the control of cancer?

2. Are sufficient tumor targets (antigens) available?

3. Can immune system be utilized to attack cancer?

4. What are the obstacles for effective cancer immunotherapy?

Does immune system play a role in the control of cancer?

• Increased cancer incidence in immuno-compromised patients.

• Occasional spontaneous regressions of cancers in immunocompetenthosts.

Does immune system play a role in the control of cancer?

Schreiber et al: Nature 2001, 410: 1107

Low affinity T cells can be activatedto reject tumor

Are sufficient tumor targets (antigens) available?

Identification of cancer antigen

1. Use T cells to screen cDNA library

2. Use acid to elute peptides from MHC molecules and then do peptide sequencing

3. SEREX: serological analysis of recombinantcomplementary DNA (cDNA) expression library

cancerimmunity.org

Human tumor antigen data base

Figure 14-11 part 1 of 2Human Tumor Antigens

Figure 14-11 part 2 of 2

Can immune system be utilized to attack cancer?

Immunotherapy of cancer

Passive immunotherapy:

Antibodies (standard therapy in certain cancer)cytokines (e.g. IL2/IL15, IFN-alpha)Cells (Adoptive transfer of autologous T cells)

Active immunotherapy:

Allogeneic bone marrow transplantation (GVH)Specific tumor vaccines (i.e. peptides, idiotype vaccine etc)Assisted antigen presentation (DC)

Production of mAb-hybridoma technique

Production of humanized mAb

Antibody therapy of cancer

1. Rituximab (anti-CD20)-B-cell non-Hodgkin’s lymphoma

2. CAMPATH 1H (CDw52)-CLL, Prolymphocytic leukemia

3. Bevacizumab (VEGF)-metastatic colorectal cancer

4. Trastuzumab (HER2/NEU)-breast cancer

5. Edrecdomab (EPCAM-1, KSA)-Colon cancer

Mechanisms of antibody-mediated anti-tumor effects

Activation of complement

ADCC

Blocking growth factor

Induction of apoptosis

Other developments for Ab-therapy of cancer

Adoptive T cell therapy of cancer

Riddell SR. 2004. J Exp Med 200: 1533-1537

Adoptive T cell therapy of cancerThe most promising immunotherapy for solid tumors. >50% of patientswith metastatic melanoma refractory to other therapies obtained objective responses. Rosenberg SA et al. Nature Med 2004, 10:909

Advantages

•High numbers of T cells can be generated in vitro

•T cells are activated in vitro, therefore bypass immune tolerance

•Select high avidity, antigen specific T cells

•Manipulate the host

Problems

•Labor intensive, technically demanding and expensive

•Adoptively transferred T cells fail to persist

•Tumor evasion

Dudley ME, et al: Cancer regression and autoimmunity in patients after clonal repopulation with antitumorlymphocytes.

Science 298:850-854.

Cytokine therapy of cancer

IFN-alpha: 90% hairy cell leukemia

IL-2: Renal cell carcinoma, melanoma

IL-15: ?

Cancer vaccination

DNA vaccination

Tumor cell vaccine

Dendritic cell vaccine

Monitoring T cell response-Tetramer

Functional evaluation of T cell response-ELISAspot assay

Nature Medicine 10, 909 - 915 (2004) Cancer immunotherapy: moving beyond current vaccines

Steven A Rosenberg, James C Yang & Nicholas P Restifo

Great progress has been made in the field of tumor immunology in the past decade, but optimism about the clinical application of currently available cancer vaccine approaches is based more on surrogate endpoints than on clinical tumor regression. In our cancer vaccine trials of 440 patients, the objective response rate was low (2.6%), and comparable to the results obtained by others. We consider here results in cancer vaccine trials and highlight alternate strategies that mediate cancer regression in preclinical and clinical models.

Obstacles of current T cell-based therapy of cancer

1. Self-tolerance

2. Suppressor cells

Myeloid suppressor cells (MSC)Granulocyte suppressors (GS)TR (CD4+CD25+)Ts: Qa-1-restrictedTr1: TGF-β producer (class II-restricted)Th3: IL-10 producer (class II-restricted)NKT: (CD1d-restricted) IL-13 producer

3. Immune evasion

How cancer cells evade CTL responses in vivo?

1. Immune ignorance (Wick et al, J EXP Med 186, 229-38, 1997;Ochsenbein et al, Proc Natl Acad Sci USA 96, 2233-8, 1999)

2. Induce clonal anergy of tumor-specific T cells (Shrikant et al, Immunity 11, 483-93, 1999)

3. Down-regulation of antigen presentation (Zheng et al,Nature 396, 373-376, 1998; Seliger et al, Immunol Today 18, 292-9, 1997)

4. Loss of tumor antigen expression (Uyttenhove et al, J Exp Med157, 1040-52, 1983)

5. Loss of co-stimulation molecules (Zheng et al, Cancer Res59, 3461-67, 1999)

How cancer cells evade CTL responses in vivo?

6. Tumors and/or their surrounding stroma may produce immunosuppressive factors such as TGF-β (Singh et al, J Exp Med 175:139-146, 1992)

7. Expression of FasL on tumor cells can induce apoptosis of T cells entering the site of tumor growth (O’Connell et al, J Exp Med 184:1075-82, 1996; Strand et al, Nature Med 2:1361-70, 1996; Hahne et al, Science 274:1363-1366, 1996; Andreola et al, J Exp Med195:1303-1316, 2002)

Questions related to this talk

1. What are the current themes of cancer immunotherapy?

2. What are the current obstacles for developing cancer immunotherapy?

3. What methods are being used for monitoring anti-cancer T cell responses?