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Tumor Immunology (II): Cancer Immunotherapy. Masoud H. Manjili Department of Microbiology & Immunology Goodwin Research Building-286 (804) 828-8779. Learning Objective. Learn how to harness the immune system to kill tumors: immunotherapy. Cancer Immunotherapy.
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Tumor Immunology (II):Cancer Immunotherapy Masoud H. Manjili Department of Microbiology & Immunology Goodwin Research Building-286 (804) 828-8779
Learning Objective • Learn how to harness the immune system to kill tumors: immunotherapy
Cancer Immunotherapy How to kill tumors without killing normal cells? To induce an immune response against the tumor that would discriminate between the tumor and normal cells: Adaptive immunity
Tumor antigens • Tumor Specific Antigens (TSA) • Are only found on tumors • As a result of point mutations or gene rearrangement • derive from viral antigens • Tumor Associated Antigens (TAA) • Found on both normal and tumor cells, but are overexpressed on cancer cells • Developmental antigens which become derepressed. (CEA) • Differentiation antigens are tissue specific • Altered modification of a protein could be an antigen
Immunotherapy • Adoptive T cell therapy (AIT) • Passive immunotherapy using antibodies • Active-specific immunotherapy by using vaccines
AIT + IL-2 against melanoma Before After
Transfer tumor-specific T cell receptor genes using retroviral vectors into patients’ T cell before AIT
Passive immunotherapy: mAbs • Herceptin: anti-HER-2/neu in breast cancer patients • Rituximab: anti-CD20 in patients with non-Hodgkin’s lymphoma • Bevacizumab: anti-VEGF in patients with advanced colorectal cancer Limitations: clearance by soluble Ags, antigenic variation of the tumor, inefficient killing or penetration into the tumor mass
Passive immunotherapy: immunotoxins • Anti-CD22 Ab fused to a fragment of Pseudomonas toxin in patients with B-cell leukemia (hairy-cell leukemia)
Passive immunotherapy: drug-linked antibodies • Anti-CD20 antibodies linked to a radioisotope yttrium-90 in patients with refractory B-cell lymphoma • Antibody-directed enzyme/pro-drug therapy (ADEPT): Antibodies linked to an enzyme that metabolizes a nontoxic pro-drug to the active cytotoxic drug
Signal I T cells Tumor Signal II Vaccination: cross presentation of tumor antigens by APCs T cell activation T cell killer function
Vaccination • Cell-based vaccines using irradiated tumors with adjuvants such as BCG • Peptide- and protein-based vaccines • DNA vaccines
Vaccination • HPV vaccine for the prevention of cervical cancer • Oncophage (gp96): a tumor-derived heat shock protein vaccine against kidney cancer and melanoma
Summary • Manipulation of tumors for the expression of new antigens is a promising approach for the induction of anti-tumor immune responses • Vaccines may be effective against residual tumors but AIT and passive immunotherapy have potentials for the treatment of primary tumors
Suggested Reading Janeway’s Immunobiology, 7th edition: Chapter 15; Pgs. 672-678