INACTIVATION OF PATHOGENS IN BLOOD PRODUCTS

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INACTIVATION OF PATHOGENS IN BLOOD PRODUCTS

• Martin H. Ellis MD
• Hematology Institute and Blood Bank
• Meir Hospital

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OUTLINE OF THE TALK

• Transfusion transmitted infections (TTI) -the
  scope of the problem
• Means available to decrease incidence of TTI
• Pathogen inactivation
• Technologies available
• Clinical trial results

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Breakdown of transfusion hazards reported to
SHOT, 1996 to 2004
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Annual risk of TTI
Developing world U.K.
150 000 12 135 000 HIV
5 million 1935 000 HCV
16 million 1144 000 HBV
? 1641 000 HTLV-I
Lancet 2005652151
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Blood-borne pathogensknown and screened by
testing

• Viruses
• HIV12
• HTLV III
• HBV
• HCV
• CMV (selected)
• West Nile virus (seasonal-US)
• Bacteria
• T. pallidum
• Protozoa
• T. cruzi (Chagas disease)

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Blood-borne pathogensknown but NOT screened by
testing

• Viruses
• EBV
• HHV-6, 7 8
• HDV
• Parvovirus B19
• Arboviruses (35 species!! including chikungunya)
• Coronavirus (SARS)
• Avian influenza
• Dengue hemorrhagic fever (Sept 2008)
• Bacteria (Gram , Gram -, anerobes)
• Protozoa (malaria, Babesia, Borrelia)
• Prions (vCJD)

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MEANS AVAILABLE TO DECREASE INCIDENCE OF TTI

• Donor selection
• Phlebotomy technique
• Diversion collection bag
• Laboratory testing
• Specialized filters (nanofiltration pores 15-40
  nm)
• PATHOGEN INACTIVATION

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PATHOGEN INACTIVATION

• ADDITION OF VARIOUS ADDITIVES TO BLOOD PRODUCTS
  TO INACTIVATE
• - viruses
• - bacteria
• - protozoa
• INACTIVATION OF PRIONS
• NOT POSSIBLE AT PRESENT

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Pathogen InactivationComponent Considerations

• Stable components
• Plasma products
• Labile components
• Platelet units
• Red cell units

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FRESH FROZEN PLASMA

• Solvent / Detergent
• EC approved
• Methylene blue
• EC approved
• UVA light psoralen (amotosalen)
• - EC approved
• Riboflavin (vitamin B2)technology
• experimental

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Solvent / Detergent (S/D) plasma

• Solvent tri-n-butylphosphate
• Detergent triton X 100
• Active against LIPID enveloped viruses
• HBV, HCV, HIV, HTLV, EBV, CMV
• Not active against PROTEIN coated viruses
• Parvovirus B19, Hepatitis A virus

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S/D plasma the process

1. FFP (single units or pheresis) thawed
2. Pooling 2 500 donors/pool
3. Incubation with S/D for 4 hrs _at_ 30C
4. S/D extracted with vegetable oil and resin
   chromatography
5. Pool is aliquoted into 200 cc units ? final
   product is called POOLED PLASMA

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S/D plasma - problems

• Large pool size
• Increased risk for parvovirus B19 and HAV
  transmission
• - abortions/hydrops fetalis
• marrow aplasia in patients with hemolytic anemia
• problematic in immunocompromised patients

PARVOVIRUS B19
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S/D plasma - problems

• Bleeding in severe liver disease and liver
  transplantation because of reduced levels of
  ?-2 antiplasmin increased fibrinolysis
  (Transfusion 19993912271234)
• Reduced levels of protein S (natural
  anticoagulant) causes increased incidence of
  venous thrombosis (in TTP patients) (Br J
  Haematol 2003121778785)

REMOVED FROM U.S. MARKET
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S/D plasma - cost

• 200 000 / QALY (Quality adjusted life year)
• (EXPENSIVE!!)

Curr Opin Hematol Sept 2008
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Methylene Blue treated plasma(MB plasma)

• Binds guanosine residues of DNA/RNA
• Light of 590 nm wavelength activates the dye ?
  genetic damage inactivation
• In use in Europe (gt 3 million units transfused),
  no adverse effects reported

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MB plasma - quality

• Reduction in activity of labile clotting factors
  of 10 30
• ( factors VIII, V and fibrinogen)
• May be associated with increase in transfusion
  requirements of FFP and cryoprecipitate
• ( 56 in a Spanish study ! Transfusion, Dec
  2001)

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Psoralen treated FFP

• Photochemical treatment
• Used for single FFP units
• Psoralen forms adducts with DNA and RNA
  prevents replication
• Effective against lipid and non-lipid enveloped
  viruses
• gt 5000 units transfused in Europe no apparent
  adverse effects

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PLATELETS

• UVA light psoralen (amotosalen)
• - EC approved
• Riboflavin (vitamin B2)technology
• experimental

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PSORALEN TREATED PLATELET UNITS

• Inactivates bacteria (Gram Gram -),
  viruses, protozoa
• Suitable for use with buffy coat or pheresis
  platelet units
• Large randomized clinical trials in
  thrombocytopenic patients have been conducted
  EuroSPRITE and SPRINT

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SPRINT main features
Control Treated
Apheresis Apheresis Product
327 318 of pts
50 39 Platelet survival
16 000 11 000 Corrected count increment (/µL)
5 5.5 Red cell unit transfusion requirements
6.2 8.4 Platelet transfusion required
6.1 4.1 Bleeding WHO grade 3-4
plt0.05
Blood 2004
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Clinical experience with INTERCEPT

• Licensed in Europe in 2002
• gt 60 000 transfusions in 11 countries
• No need for gamma irradiation (!)
• No requirement for bacterial testing, emerging
  virus testing
• No increase in platelet use overall
• Chikungunya outbreak in Reunion required rapid
  deployment of system-satisfactory!

Consensus Conference on PI, US NIH, 2007
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RIBOFLAVIN TREATED PLATELET UNITS

• Vitamin B2 non-toxic, no need to remove
• Absorbs light and intercalates into DNA and RNA
• Causes strand breakage inhibits replication
• Clinical applications currently being investigated

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RED CELL UNITS

• Less progress compared to other components
• Psoralens do not work UVA light is absorbed by
  Hemoglobin!

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RED CELL UNITS

• FRALES (Frangible Anchor Linker Effectors)
• 3 part molecules
• Activation is pH dependent
• Inactine
• Causes a stop signal that inhibits DNA RNA
  polymerase activity
• Unsuccessful clinically neoantigen formation
  causing positive crossmatches

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Transfusion Med Rev 2008
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Ideal Pathogen Inactivation System

• Single units treated
• Absence of toxicity
• Safe in all patient populations (pregnancy,
  neonates, renal failure, liver disease,
  immunocompromised)
• Reasonable cost

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Is pathogen inactivation a worthwhile enterprise?

• Real medical need?
• Technology and industry driven?

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It depends on What is acceptable risk?
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Blood Transfusion Circa 2005 2010 2015?
Transfusion 2000