Si Quaeris Peninsulam Amoenam Circumpice

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Si Quaeris Peninsulam Amoenam Circumpice

• Rationale for Cancer Gene Therapy

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• There is a capacity of virtue in us and a
  capacity of vice to make your blood creep
  -RW Emerson
• If cancer is the vice, how can the virtue be
  used to subdue the vice?

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• Rogue cells develop among millions of virtuous
  cells and reap havoc. These few rogues can be
  approached with
• Poisons (alkylators, anti-metabolites, nucleoside
  analogs, radiation)
• or
• Applying the checks and balances inherent in the
  host
• These choices represent fundamentally different
  approaches

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• Si Quaeris Peninsulam Amoenam Circumpice

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• It is more important to know what kind of
  patient has the disease, than what kind of
  disease the patient has
• W. Osler
• What does the patient have to offer?

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• Define Gene Therapy
• Probably is replacing p53, ras antisense,
  vaccines
• Probably is not poisons, radiation
• How about targeting therapies ?
  antiangiogenesis, tyrosine kinase inhibitors

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• Supreme Court Justice Potter Stewart

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If you gotta ask, youll never know

• Neal Armstrong What was it like to walk on the
  moon?
• Louis Armstrong What is Jazz?
• Lance Armstrong What was it like to win a fifth
  Tour de France?

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• Cancer The result of a flaw in the normal
  cellular/host checks and balances
• Gene Therapy Use of a hosts inherent
  facilities/abilities or an understanding of that
  infrastructure to correct the consequences of
  that flaw.

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Rationalism and Empiricism

• Currently, using the host is a only a
  rationalists paradigm
• Treating Phantom Limb Pain
• Clinical progress relies on empiricism

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The 100 A Ranking of the Most Influential
Persons in History (Michael J. Hart)

• 1-Muhammad 2-Isaac Newton 3-Jesus Christ 4-Budda
  5-Confucius 6-St. Paul 7-Tsai Lun 8-
  JohannGutenberg 9- Christopher Columbus 10-Albert
  Einstein 11-Louis Pasteur 12-Galileo Galilei
  13-Aristotle 14-Euclid 15-Moses 16- Charles
  Darwin
• 57- The empiricist

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Gregor Mendel
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Safety

• Fatal Systemic Inflammatory Response Syndrome in
  a Ornithine Transcarbamylase Deficient Patient
  Following Adenovirus Gene Transfer
• (Raper Mol Genet Metab 200380148-158)

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Gene Therapy Approaches

• Virotherapy/ Gene Transfer
• Tumor Necrosis Factor signaling as a target

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Vector Trials (Oncolytic Viral Therapy)

• Oncolytic Vectors for Cancer Destruction
• Obstacles
• Target the cancer, spare the normal cells
  (replication competent viruses can be dangerous)
• Host antibodies to viral vectors clear virus
  before virus infects cells
• Delivery to enough cancer cells

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Vector Trials (Oncolytic Viral Therapy)

• P53
• Cancer cells ( 50-70) lack p53 pathway.
• ONYX-015 adenovirus lacking E1B (cannot
  replicate in cells with a normal p53 pathway).
• ONYX replicates in and lyses cancer cells.
  Cancer cells have abnormal RNA export, so viral
  RNA is exported into other cells.
• Head Neck Cancer tumors with lack of normal
  p53 showed better response, still better in
  combination with chemotherapy. Currently in
  Phase III (Lamont, 2000).

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Vector Trials (Oncolytic Viral Therapy)

• Rexin-G
• Gene designed to interfere with cyclin GI gene by
  integrating in host DNA delivered by viral vector
• Phase I 3/3 patients with pancreatic cancer had
  tumor growth arrest.
• FDA orphan drug approval (Gordon, 2004)
• Now being evaluated for colon cancer use
• HSV-tk
• Adenovirus carries HSV-tk gene.
• Gencyclovir is toxic once metabolized by HSV-tk.
  Randomized controlled glioblastoma study median
  survival increased from 39 weeks to 70.6 weeks
  (Immonen, 2004)

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Vector Trials (Oncolytic Viral Therapy)

• INON 201
• P53 mutated in 50-70 of human cancers
• Adenovirus vector containing p53
• Phase 3 studies underway
• Phase I studies prostate, ovary, glioma, bladder
  completed. (Merritt, 2001 Swisher, 2003)
• Gendicine
• Modified adenovirus delivers p53
• Regulatory approval in China for squamous cell
  cancer.

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Randomized Phase III trial of Fludarabine Plus
Cyclophosphamide With or Without Oblimersen
Sodium (Bcl-2) in Patients With Relapsed or
Refractory Chronic Lymphocytic Leukemia (OBrien,
JCO, 2007)

• Bcl-2 expression predicts aggressiveness and
  confers tumorigenicity in CLL
• Oblimersen antisense oligonucleotide
  downregulates Bcl-2 in vitro
• CR/PR correlates w/ extended TTP and
  survival(plt.0001)
• oblimersen/Chemo(n120)
  Chemo (n121)
• CR/PR 17
  7 (p.025)
• Frequent thrombocytopenia, rare TLS and
  cytokine release rxn in oblimersen treated group
  

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TNF-Background

• Cytokine involved in apoptosis, inflammation,
  cell survival
• Chromosome 617KDa protein
• Produced by Macrophages, T-Lymphocytes, NK cells
• Acts via TNF binding receptors (TNFR-1, TNFR-2)
• TNFR-1 is expressed in all cells and has a Death
  Domain(DD)
• DD activation induces downstream signalling,
  procaspace, endonuclease activation, DNA
  fragmentation and apoptosis
• Nuclear Factor KB(NF-KB), constituitively
  produced in many tumor cell types prevents
  apoptosis. IKB Inhibitor of NF-KB.
  ProteosomesDegrade IKB

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TNF- Clinical Trials

• 4 multicenter studies of isolated limb perfusion
  (ILP)for extremity STS involving over 700
  patients
• 33 CR(100necrosis)
• 76 ORR
• 82limb salvage
• 35 European centers now use this approach for
  high grade STS

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TNF Clinical Trials

• 7 melanoma studies involving over 300 patients
• 60-90 CR 11-22PR
• In ILP for melanoma in transit
• melphalan
  TNF/melphalan
• CR() 50
  70-90
• ORR() 80
  95-100

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TNF background-angiogenesis

• Angiogenesis is necessary for sustained tumor
  growth ie the angiogenic switch
• Tumor Associated Vasculature (TAV) is chaotic
  with aberrant, discontinuous endothelium
• This poor vasculature is more suseptible to TNF
• eg there are far more TNF alpha receptors in TAV
  than normal endothelium
• Tumor hemorrhegic necrosis is preceded by
  endothelial cell necrosis
• With TNF induced hyperpermeability, there results
  synergy with chemotherapy drug delivery

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TNF Correlative Studies

• Angiography confirms TAV is selectively destroyed
  in IPL (normal vasculature remains intact)
• Histology confirms massive hemmorhagic necrosis
  in melanoma with TAV destroyed non-melanotic
  endothelium intact (Noonan, Br J Ca, 1996)

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TNFerade

• TNFerade a replication deficient adenovector
  with radiation inducible TNF alpha expression
• 30 patients treated w/ RT and weekly intratumoral
  injections (7 injections 7 dose levels)
• 70 ORR (21/30) 5CR,9PR,7minimal response
• In 4/5 with synchronous lesions, there was
  difference in response between the injected and
  uninjected tumors
• TNFerade toxicities fever(22),site
  pain(19)chills(19). No DLT seen (Senzer,
  JCO, 2004)

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TNFerade

• GV-001.004 A Randomized Phase II/III study of
  TNFerade Biologic with 5-FU and RT for First Line
  Therapy of Unresectable Locally Advanced
  Pancreatic Cancer
• RT/FU vs RT/5FU/TNFerade followed by
  Gemzar/-Tarceva

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Checks and BalancesTNF Pathway

• TNF induces apoptosis
• NF-KB anti-apoptosis
• IKB inhibits NF-KB (induces apoptosis)
• Proteosomes (degrade IKB) anti-apoptosis
• Bortezemab (inhibits proteosomes) induces
  apoptosis

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Targeting NF-KB

• TNF activity is assc with reactive 02 radicals
  NF-KB induces neutralizing enzymes (superoxide
  dismutase)
• Inactivating NF-KB sensitizes to TNF (Orlowski,
  2002)
• COX-2 inhibitors block NF-KB pathways, sensitize
  to TNF (Delhalle, Oncogene, 2002)
• Overexpression of the NF-KB inhibitor (IKB) can
  similarly induce apoptosis

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Targeting NF-KB

• Bortezemab A selective proteosome inhibitor.
  Blocks degradation(by proteosomes) of inhibitor
  of NF-KB (IKB) and thereby promotes apoptosis
• Inhibition of proteosomes active in Multiple
  Myeloma leads to less degradation of IKB, and
  therefore less NF-KB activity and more apoptosis.

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Targeting NF-KB Bortezemib

• N192, about half had 3 or more regimens for
  Multiple Myeloma (MM)
• Results
• 35 RR
• 7 with undetectable myeloma protein
• 12 detectable only by immunofixation
• Median duration of response was 12 months
• 
  (Richardson. NEJM, 2003)

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Tumor Necrosis Factor Related Apoptosis Inducing
Ligand (TRAIL)

• Activates the TNF Death Receptors
• Triggers an apoptosis cascade
• In vitro activity in many cancer cell types

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TRAIL and proteosome inhibition

• cervical cancer p53 inactivation by viral E6
  followed by protesome degradation and cell
  survival (E6 and proteosome activity interfere
  with p-53 induced apoptosis)
• MG 132 (proteosome inhibitor) given with
  recombinant TRAIL led to enhanced WT p53
  expression, and increased death receptor
  activity.
• Death Receptor antibodies (DR 4) reversed the
  effect
• (Hougarty, Int J
  CA, 2006)

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Conclusions

• Viruses can be used to successfully deliver genes
  whose products activate prodrugs, or are directly
  cytolytic
• Enhancing TNFs apoptotic activity represents a
  promising approach to cancer therapy

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Why Were Losing The War On Cancer (And How To
Win It) (Leaf, Fortune 2004)

• Yet virtually all these experts offered
  testimony that, when taken together describes a
  dysfunctional cancer culture-a groupthink that
  pushes tens of thousands of physicians and
  scientists toward the goal of finding the tiniest
  improvements in treatments rather than genuine
  breakthroughs
• Is this a description of the clinical trials
  approach? Is there room for the rationalists?

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• Man will never penetrate outer space
• -Albran, 1952

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• Man will never penetrate outer space without a
  rocketship
• -Albran, 1962