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Angiotherapy and gene therapy in cancer treatment These slides provide an overview of angiotherapy and gene therapy in cancer Dr. Momna Hejmadi, University of Bath This resource created by Dr. Momna Hejmadi, University of Bath, 2010, is licensed under the Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/2.0/uk/ N.B. Some images used in these slides are from the textbooks listed and are not covered under the Creative Commons license as yet
Angiogenesis-overview Nature Reviews Drug Discovery1, 415-426 (2002)
Endostatin • Discovered in 1995 by Judah Folkman et al • Phase I clinical trial in 1999 Dr. James Watson predicted that Dr. Folkman would cure all cancer within 2 years Dr. Folkman’s response “If you are a mouse and have cancer we can take good care of you. However, in our experiments we mostly sacrifice the mice. So, I don't know if that qualifies as taking good care”
(Courtesy of L. Heuser and R. Ackland, University of Louisville, USA Angiogenesis: an organizing principle for drug discovery by Judah Folkman Nature Reviews Drug Discovery 6, 273-286(April 2007)
Categories of anti-angiogenics Anti-angiogenic molecules fall into 5 categories • inhibitors of angiogenic growth factors:VEGF, bFGF, PDGF • protease inhibitors: prevents the breakdown of the surrounding matrix, which is needed for blood-vessel growth • Analogs of endogenous inhibitors of angiogenesis e.g. endostatin; • inhibitors of cellular adhesion molecules • molecules with undefined mechanisms
Angiostatin 38kDa fragment of plasminogen Endostatin 20kDa fragment of collagen XVIII Endothelial cell specific Complete regression in mice No drug resistance ‘cryptic’ angiogenesis inhibitors Inactive until released from the parent protein by enzymatic cleavage
Anti-VEGFR2 therapy (c,d) Anti-VEGFR2 prunes immature vessels, leading to a progressively 'normalized' vasculature (e) Further treatment leads to a vasculature that is inadequate to sustain tumour growth by day 5. (f) Perivascular cells expressing GFP (under the control of the VEGF promoter) envelope some vessels in the tumour interior. (g) A perivascular cell, presumably a fibroblast, leading the endothelial sprout (arrow).
Efficacy of thalidomide as an anti-angiogenic agent Before treatment after treatment Blood-flow maps a | before treatment and b | six months after treatment of a patient with metastatic renal-cell carcinoma with thalidomide.
Haematological malignancies? Neovasculature around bone marrow in certain leukaemias. Anti-angiogenic drugs could therefore be useful in haematolgical malignancies Bone marrow from a child with newly diagnosed acute lymphoblastic leukaemia reveals intense neovascularization, with microvessels of variable diameters. normal bone marrow (from a child with a non-neoplastic disease) shows normal microvasculature of uniform-sized vessels.
Combination with chemotherapy Dosing schedule differences between conventional chemotherapy (red) and anti-angiogenic chemotherapy
References 1) Angiogenesis modulation in cancer research:Novel clinical approaches by M Cristofanilli, C Charnsangavej‡ and GN.Hortobagyi Nature reviews drug discovery VOL 1 JUNE pp 415 (2002) 2) Angiogenesis: an organizing principle for drug discovery by Judah Folkman Nature Reviews Drug Discovery 6, 273-286(April 2007)
Newer cancer therapiesgene therapy Direct genetic modification of cells in patients
delivery 3 challenges in gene therapy delivery delivery • Package the gene • Protect the gene • targeted delivery to the nucleus and release in an active form
Carrier molecules designed specifically to enter cells & deposit therapeutic genes Vectors ‘Trojan horses’ that sneak the gene into the cell
Viral vector strategy Replication & virulence genes can be substituted with therapeutic genes
Retroviral vectors designed to enter cell and deposit genesSpecially constructed to prevent the generation of replication competent retroviruses (RCR) • Advantages • long-term expression • low toxicity • high capacity • low antivector immunity • Problems • Lack of cell specificity • Random splicing into host DNA
Minimal HIV vector plasmid All genes coding for enzymatic or structural HIV proteins have been removed. (1) consisting of the CMV/HIV LTR hybrid promoter followed by the packaging signal ( Ψ), the rev-binding element RRE for cytoplasmic export of the RNA, the transgene expression cassette consisting of internal promoter(s) and transgene(s), and the 3' self-inactivating (SIN) LTR. Together with the HIV vector plasmid (1), the HIV packaging plasmid (2), HIV rev (3), and an envelope expressing plasmid (4) are needed for HIV vector production. Gene Therapy (2005) 12, 1089–1098
Adenoviral vectors do not insert into genome temporary lack of specificity strong immune response
Adeno-associated viral vectors Integrate into genome but small in size Nature Reviews Genetics 1; 91-99 (2000);
Non-toxicno immune responsereduced specificity Non-viral Vectors
Gene gun Non-viral Vectors liposomes (lipoplexes)
Gene therapy targets Germ line gene therapySomatic cell gene therapy Gene augmentation Gene replacement Specific inhibition of gene expression Targeted cell death
Gene augmentation most therapies simply add a useful gene into a selected cell type to compensate for the missing or flawed version. Useful in treating loss of function mutations such as Tumour suppressor genes
Gene replacement This strategy replaces the mutant copy with a correctly functioning copy in situ. Useful for gain of function mutations such as oncogenes
Specific inhibition of gene expression Involves silencing of specific genes like activated oncogenes, by using molecules that degrade RNA transcripts. Strategies include Antisense therapy siRNA (small interfering RNA) Ribozymes etc
Targeted cell death Tissue-specific delivery of drugs using vectors resulting in tissue specific toxicity. Direct approach
Targeted cell death Indirect approach stimulating an immune response against selected cells or eliminating the blood supply.
Gene therapy in cancer http://www.wiley.co.uk/genetherapy/clinical/
Gene therapy in X-SCID patients Rare condition caused by the lack or reduction in the immune system (‘bubble baby syndrome’) Patients cannot make T lymphocytes and their B lymphocytes fail to make essential antibodies for fighting infections. X-SCID caused by mutations in the X-linked gene IL2RG, which encodes the common gamma chain (gc) of the lymphocyte receptors for interleukin-2 (IL-2) and many other cytokines Severe Combined Immunodeficiency (SCID)
Gene therapy by injection of retrovirally transduced autologous CD34+ hematopoietic stem cells (HSCs). insertional mutagenesis near the proto-oncogene LMO2 promoter (Science, 302:415-419, October 17, 2003) 2/11 X-SCID patients developed leukemia
References Chapter 16: Biology of Cancer by RA Weinberg Human gene therapy by Ioannou, Panos A(www.els.net) Nature Reviews Cancer (2001) vol 1 pp 130-141 by Francis McCormick