Cockroach allergen standardization

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Cockroach allergen standardization
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Cockroaches
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Cockroach allergen standardization

• Clinical studies
• Developing the appropriate surrogate
• Correlation
• Depletion studies
• Fab and scFv combinatorial libraries to cockroach
  allergens

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Why is cockroach allergy important?

• Ubiquitous
• Difficult to control
• Associated with asthma
• Standardization of cockroach allergen extracts
  supported by the Allergenic Products Advisory
  Committee on February 10, 2000

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Why is cockroach allergen standardization
important?

• To the patient
• More accurate diagnosis
• Safer and more effective immunotherapy
• To the physician/scientist
• Better science (if you cant measure it, you
  cant study it)
• Pathophysiology
• Epidemiology
• Environmental control
• To the FDA
• Safer, more effective product

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Initial studies Laboratory

• Develop/adapt methods for allergen determination
• Compare allergen content of different lots

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Conclusions

• Commercially available cockroach allergen
  extracts
• vary widely in protein content, Bla g 2 content,
  SDS-PAGE banding pattern, and overall
  allergenicity.
• appear to be less potent and contain less Bla g 1
  than the candidate reference extracts
• Established that cockroach allergen vaccines need
  to be standardized

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Next stage Clinical

• skin testing, histamine release, IT data
• establish biological unitage and ideal dosing
  ranges

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Goals

• Obtain valid clinical data on the biological
  potency of three commercial German cockroach
  allergen extracts
• Develop surrogate potency testing

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Goals

• Obtain valid clinical data on the biological
  potency of three commercial German cockroach
  allergen extracts
• Develop surrogate potency testing

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ID50EAL testing (Intradermal Dilution for 50 mm
Sum of Erythema Determines Bioequivalent Allergy
Units)
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NIAID Inner City Asthma Consortium
established in FY 2002 to explore and evaluate
promising new strategies for the treatment of
asthma among minority children residing in the
inner city. This consortium of basic scientists
and clinical investigators will conduct clinical
studies to elucidate the immunopathogenesis and
natural history of asthma in this population.
From the FY 2003 Budget Justification Narrative,
NIAID, http//www.niaid.nih.gov/director/congress
/2002/cj/narrative.htm
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NIAID Inner City Asthma Consortium steering
committee

• William W. Busse, MD, Chair
• Gordon R. Bloomberg, MD
• Peyton A. Eggleston, MD
• Peter Gergen, MD, MPH
• James Gern, MD
• Rebecca S. Gruchalla, MD, PhD
• Meyer Kattan, MD
• Carolyn M. Kercsmar, MD
• Andrew H. Liu, MD
• Floyd J. Malveaux, MD, PhD

• Herman Mitchell, PhD
• Wayne Morgan, MD, CM
• George T. OConnor, MD, MS
• Jacqueline A. Pongracic, MD
• Hugh A. Sampson, MD
• Sampson Sarpong, MD
• Ernestine Smartt, RN
• Robert C. Strunk, MD
• Stanley J. Szefler, MD

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Recruitment

• Inclusion criteria
• 18 to 65 years of age
• history of allergic disease, such as allergic
  rhinitis, related to exposure to the allergen of
  interest
• puncture sum of erythema diameter responses (SE)
  to the allergen concentrate of 30 mm.

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Recruitment

• Exclusion criteria
• Asthma with use of systemic steroids in the past
  12 months
• Peak flow lt 75 predicted at the time of testing
• Skin coloring or condition that would preclude
  the measurement of erythema responses
• Dermographism (gt 4 mm SE following saline skin
  test)
• Immunotherapy past or present - with the test
  allergen
• Current use of antihistamines, tricyclic
  antidepressants, MAO inhibitors, and beta-blockers

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Allergen extracts chosen

• German cockroach
• Approved for skin testing
• 50 glycerol
• 3 different manufacturers

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RP1 pooled monospecific rabbit sera against Bla
g 1, 2, 4 and 5 RP2 rabbit anti-German
cockroach RP3 human serum pool S1CR
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Timetable

• Steering committee approval - done
• Study centers identified - done
• Order extracts - done
• IRB approvals - done
• IND approval - done
• Distribute materials - done
• Proficiency testing - in process
• Proceed with study

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Goals

• Obtain valid clinical data on the biological
  potency of three commercial German cockroach
  allergen extracts
• Develop surrogate potency testing

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Surrogate tests to be evaluated

• Competition ELISA (using study sera)
• Specific allergen testing
• Direct ELISA
• Rabbit hyperimmune sera
• Clonal chicken and rabbit scFv and Fab
• Two-site ELISA
• Antibody microarray profiles
• Sensitized mast cell lines (H. Sampson)

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Figure legends

• Antibody/detector system
• Antigen/analyte

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Competition ELISA with pooled allergic human sera

• Examples mites, grasses
• Advantages
• quantitative
• reflects spectrum of allergen recognition
• does not require identification of relevant
  allergens
• Disadvantages
• use of pooled sera
• effects of fluctuations in individual allergens
  difficult to measure

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ELISA with monospecific antiserum

• Advantages
• quantitative
• monospecific
• Disadvantages
• need to identify relevant allergen(s)

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Two-site ELISA with monoclonal antibodies

• Advantages
• specificity
• Disadvantages
• specificity
• need to identify relevant allergen(s)
• cross-reactivity

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Antibody microarray

• Advantages
• quantitative
• reflects spectrum of allergen recognition
• does not require identification of relevant
  allergens
• Disadvantage
• New technology initial development will be labor
  intensive and expensive

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Conclusions

• Standardized German and American cockroach
  allergen vaccines will
• facilitate definitive studies on the role of
  cockroach allergens in inner city asthma, and on
  the best methods for eradication and treatment
• make for safer and more effective products