Potency Assays For Recombinant Viral Vaccines For Cancer Therapy

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Potency Assays For Recombinant Viral Vaccines For
Cancer Therapy
Kelledy Manson Sr. Director Bioanalytical
Development Therion Biologics Corporation February
9, 2006
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Agenda

• Introduction to Therion products
• Challenges for Therion potency assays
• Matrix approach to potency evaluation
• Surrogate assays
• Questions and Answers

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Introduction to Therion Products

• PANVAC-VF
• Phase 3 for the treatment of patients with
  metastatic pancreatic cancer
• PROSTVAC-VF
• Phase 2 for the treatment of patients with
  metastatic prostate cancer

Poxviruses deliver genes encoding target tumor
antigens and immune-enhancing proteins
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Complex Biologic Function
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Complex Biologic Function
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Poxvirus Vectors

• Vaccinia (V)
• Replicates in multiple cell types
• Replication limited by rapid host immune response
• Fowlpox (F)
• Replicates only in avian cells
• Infects and expresses proteins but does not
  replicate in mammalian cells
• Protein expression not inhibited by host immune
  response to fowlpox

Administered in a heterologous prime-boost
regimen V F F F
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Vaccines Express Tumor-Associated Antigens and
Costimulatory Molecules

• Tumor-Associated Antigens (TAA)
• PANVAC-VF
• CEA
• MUC-1
• PROSTVAC-VF
• PSA
• TRIad of COstimulatory Molecules -TRICOM
• B7.1
• LFA-3
• ICAM-1

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Therion Biological Potency Assays

• Measure biological activity that relates to
  product function
• Ensure lot-to-lot consistency
• Stability-indicating
• Minimize variability
• Include suitable reference standards

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Challenges for Therion Potency Assays

• Complex products with multiple components
• Two distinct viral vectors with different
  biological characteristics
• One or two tumor-associated antigens
• Human costimulatory molecules
• Series of events required for biological activity

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Statistical Approach to Biological Assay
Development

• Statistical design of experiments
• Identification of the sources of assay
  variability
• Informs the number of replicates or doses for
  accuracy and precision
• May lead to assay modifications and refinements
• Accommodates use of multiple lots of reference
  standard

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Evolution of Therion Potency Assays
DEVELOPMENT STAGE
ASSAY TYPE
Plaque titration
Phase 1-2 Trials
Biological activity
MATRIX APPROACH Critical steps required for
biological function
Phase 3 Trials
Approved Product
Quantitative Surrogate
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Complex Biologic Function
BIOLOGICAL ACTIVITY
PROTEIN EXPRESSON
GENETIC CODING
INFECTION
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Summary of Matrix Assays to Measure Critical Steps
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How is TRICOM Designed to Work?
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The In Vitro TRICOM Assay

• Activation of human T cells in vitro
• Signal 1 Non-specific
• Signal 2 Poxvirus-infected cell line expressing
  TRICOM
• T cell activation quantitated by measurement of
  cytokine secretion

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Design of Experiments for In Vitro TRICOM Assay

• Sources of variability in a single experimental
  design
• Day-to-day
• Operator-to-operator
• Naïve T cell donor source
• Assay plate-to-plate
• Well-to-well
• ELISA plate to ELISA plate
• Dose-response to different multiplicities of
  infection
• Designed to increase sensitivity to allow
  assessment of lot-to-lot consistency and stability

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Surrogate Assays

• Evaluating surrogate assays for biological
  function
• Analytical
• Quantitative
• More reproducible
• Correlation with biological activity (e.g., use
  of quantitative flow cytometry to replace in vivo
  potency assay)

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Summary

• Complex products require more than one assay to
  assess activity
• Matrix of analytical assays can be used to
  evaluate critical steps
• Statistical approach for biological activity
  assays is critical for development and validation
• Quantitative surrogate assays can replace or
  supplement variable biological assays for
  consistency and stability assessment

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Potency Assays For Recombinant Viral Vaccines For
Cancer Therapy
Kelledy Manson Sr. Director Bioanalytical
Development Therion Biologics Corporation February
9, 2006