TSE Task Force Prion reduction evaluation in the manufacturing of plasma protein therapies

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TSE Task ForcePrion reduction evaluation in the
manufacturing of plasma protein therapies

• Dr. Henry Baron,
• Chair, PPTA TSE Task Force
• FDA TSE Advisory Committee
• The Hilton Hotel, Silver Spring
• 14 October 2004

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FVIII / vWF Products

• Study Parameters
• Prion strain 263K hamster adapted Scrapie
• Spike preparations
• Microsomes
• Purified PrPSc
• Detergent solubilized brain homogenate
• 10 brain homogenate
• Prion detection / quantification method CDI
  Western blot, bioassay
• 2 - 3 independent runs/spike preparation

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FVIII / vWF Products

• Results
• Product A Consecutive salt precipitation
  (Preliminary data on Prion Reduction Factor)
• Microsomes 2.5 log10 /3.2 log10 /2.5 log10
  mean 2.7 log10
• Purified PrPSc 2.9 log10 /3.3 log10 /2.8 log10
  mean 3.0 log10
• Product B 3 PEG precipitation (Published data
  on Prion Reduction Factor)
• 2.2 log10 infectivity
• 3.0 log10 PrPRES by Western blot
• Product C (Heparin-affinity purified) 3.5 PEG
  precipitation (Preliminary data on Prion
  Reduction Factor)
• Microsomes 3.5 log10/3.5 log10
• Detergent solubilised BH 4.2 log10/4.2 log10

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MAb purified F VIII

• Prion strain 263K hamster adapted Scrapie
• Spike preparations
• Brain homogenate (Mab affinity step)
• SD treated and filtered brain homogenate (DEAE
  step)
• Prion detection / quantification method Hamster
  bioassay
• Manufacturing stage studied MAb affinity
  chromatography and DEAE Sephadex
• 2 independent runs/spike preparation
• Result (Prion Reduction Factor)
• MAb affinity chromatography 4.1 log10
• DEAE Sephadex 3.5 log10

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FIX Products

• Study Parameters
• Prion strain 263K hamster adapted Scrapie
• Spike preparations
• Microsomes
• Purified PrPSc
• Detergent solubilized brain homogenate
• Prion detection / quantification method CDI
  Western Blot
• 2 independent runs/spike preparation

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FIX Products

• Results
• Product A Manufacturing stage studied Planova
  filters in series
• 35N
• 15N
• Result for detergent solubilized brain homogenate
  (Prion Reduction Factor) 4.1 log10 mean

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FIX Products

• Product B Manufacturing stage studied
  Nanofiltration (YM 100)
• Result (Preliminary data on Prion Reduction
  Factor)
• Microsomes ? 3.3 log10 / ? 3.7 log10 mean ?
  3.5 log10
• Purified PrPSc ? 3.6 log10 / ? 3.6 log10 /
  mean ? 3.6 log10
• Product C Manufacturing stage studied Salt
  precipitation
• Result (Preliminary data on Prion Reduction
  Factor)
• Microsomes ? 3.8 log10 / ? 3.6 log10 mean ?
  3.7 log10
• Purified PrPSc ? 2.9 log10 / ? 3.1 log10 /
  mean ? 3.0 log10

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IGIV
Prion Clearance by Coupled vs Independent Steps
a Bioassay n 1, confirmed by Western blot
measurement of PrPRES, n 3 b Spiked once at
the beginning of coupled steps consisting Cryo,
Frac. 1, and Frac. III separation c Spiked at
the beginning of each independent step d Not
determined by bioassay, the number is derived
from the coupled study. Western blot consistently
shown 1 log clearance
Conclusion Prion infectivity reduction can be
additive for these steps
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Single Steps vs. Combination of Steps

• Immunglobulin Production
• LRF LRF combined steps
• Depth filtration 1 4.5
• 7.2
• Depth filtration 2 2.8
• Sum 7.3
• Brain homogenate spiked to intermediates
• Prion reduction factor determinded by
  infectivity
• Gregori et al. 2004

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Risk of vCJD Donors in the UK Donor Population

• To date, 15 blood donors diagnosed with vCJD, of
  which 9 contributed to 20 pools used to
  manufacture plasma protein therapies
• Thus from 1980-1998 , the incidence of vCJD
  donors amongst the donor population was
• 15 / (1,907,000 x 18 years)
• 0.44 vCJD donors per million donors per year
• Based on the time period of potential exposure
  to BSE until when UK plasma was no longer used
  for manufacture
• In 1997 the yearly number of UK donors was
  1,907,000
• (DNV vCJD risk assessment 1999)

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BSE Exposure EU vs. UK
i.e. 100-fold lower EU vs UK vCJD exposure All
UK vCJD infected donors contributed prior to the
introduction of active testing for BSE.
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Active vs. Passive Detection of BSE (EU excluding
UK)
4-fold increase in BSE detection due to active
testing
From Report on the Monitoring and Testing of
Ruminants for the Presence of Transmissible
Spongiform Encephalopathy (TSE) in the EU in
2003, including the results of the survey of
Prion Protein Genotypes in Sheep Breeds (EU
report)
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Conclusions

• Comparability of data from different PPTA member
  companies using different investigative
  approaches gives confidence that current systems
  are working to ensure efficient prion removal,
  even though prions have never been shown to exist
  in human plasma.
• These efforts made by PPTA member companies
  represent enormous investments in applying the
  precautionary principle and providing reassurance
  on the safety of plasma products.
• Balanced approaches are necessary to ensure both
  safety and availability of life-saving plasma
  protein therapies