Transcript Pathogen Inactivation Making Decisions About New
PROTECTING THE BLOOD SUPPLY FROM EMERGING PATHOGENS: THE ROLE OF PATHOGEN INACTIVATION (PI)
M.A. Blajchman, MD, FRCP(C) McMaster University Canadian Blood Services
WHAT IS PATHOGEN INACTIVATION?
● A process of killing micro-organisms in biological fluids including: - Viruses - Bacteria - Parasites ● PI is a well-established approach to treat fractionated blood products (proteins) during manufacture.
● PI is thus currently being explored to increase the safety of plasma, platelets and blood components including RBCs.
REDUCING THE RISK OF TRANSFUSION TRANSMITTED INFECTIONS
• • • • • • • •
Donor history Donor examination Donor testing Diversion of initial aliquot Leukoreduction Post donation information Donor deferral registries Limit donor exposure
NEW TEST IMPLEMENTATION AND DECLINING RISK OF TA-VIRAL INFECTIONS IN THE U.S.
C u l t u r e +
Vamvakas EC, Blajchman MA. Blood 2009; 113: 3406-3417
Vamvakas EC, Blajchman MA. Blood 2009; 113: 3406-3417
CURRENT DONOR TESTING FOR INFECTIOUS DISEASE
• Syphilis (1938) • Anti-HIV • Anti-HTLV • HIV p24 Antigen • WNV NAT • Anti-HBc ● HB s Ag ● Anti-CMV ● Anti-HCV ● HIV and HCV NAT ● Bacteria (2004) ● Chagas Disease (2009)
DONOR TESTING FOR INFECTIOUS DISEASE IN THE U.S.
HBV NAT WNV HIV HCV NAT Anti-HCV HIV Ag Chagas Syphilis 1938 HBsAg Anti-HTLV ALT Anti-HBc Anti-CMV Anti-HIV
Malaria HHV8 Babesia Leishmania Foamy viruses HEV
1970 1975 1980 1985 1990 1995 2000 2005 2010
ONGOING AND UNTESTED RISKS TO THE BLOOD SUPPLY Any agent known to cause disease in man and that has a viremic or bacteremic phase during its clinical course.
Agents for which there are no routine screening tests in place include (partial list):
vCJD Malaria HHV-8 Parvovirus Babesia HAV HPV Dengue Rickettsia Chikungunya Foamy viruses HEV Leishmania SARS etc.
RISKS OF TRANSFUSION-TRANSMITTED INFECTIONS IN THE UNITED STATES (1984-2005) Blajchman MA, Vamvakas EC. NEJM 2006; 355: 1303-1305.
RISK OF TA-BACTERIAL SEPSIS
• Data from 2001 • Canadian data published in 2007 • ARC data published in 2007 • Passport data reported in 2008 • Murphy W et al. data published in 2008
Bacterial-Related Septic Transfusion Reactions*
(reported rates per million platelet units transfused)
Study Perez (2001) Kuehnert (2001) Ness (2001) AP 31.8
9.8
74.5
WB Platelets 71.8
10.6
67.0
RBCs 5.8
0.2
ND AP = apheresis platelets “It is likely that only the most severe forms of transfusion reactions are reported and under reporting undoubtedly occurs”.
*From McDonald CP and Blajchman MA Transfusion Microbiology 2008.
Bacterial Testing Apheresis Platelets at CBS & HQ*
• 82,004 units tested, BacT/alert, aerobic only • 70 units initially positive – 6 confirmed positive • 2 false negative PC resulted in TA-bacterial sepsis – Salmonella sepsis in 61 yr. old man, with AML and neutropenia.
–
Serratia marcesens
cultured at autopsy in a 3 year old girl with leukemia who died of multisystem organ failure 21 hours after transfusion with contaminated apheresis platelets.
*Ramirez-Arcos et al, Transfusion 2007
American Red Cross Bacterial Screening of Apheresis Platelets*
Single bottle culture of 1,004,206 AP donations (2004-06) • 186 True Positives (1:5,399) ● • False negative cultures resulted in 20 reported septic reactions, including 3 fatalities (passive reporting) Partially associated with the use of 2-arm AP procedures ● 13 of 20 reactions occurred with day 5 APs
*
Eder AF et al. Transfusion 2007; 47: 1134-42.
THE PASSPORT STUDY
• FDA mandated post-marketing surveillance of 7 day apheresis platelets (AP) • Participation of 51 US Blood Centers • Assessed the risk of bacterial contamination in 7-day AP compared to 5-day AP • Cultures (BacT/ALERT, 2 bottles, 5 ml each) • Release: 100% at 24-36 h post-collection • Surveillance: PC inventory on day 7 • Passive reporting of clinical outcomes
PASSPORT Surveillance Cultures
•
4369 PC initially culture negative
– –
Re-tested after day 7 3 true positives: S. aureus , S. epidermidis,
S. veridans
•
Residual risk: 686 per million PC (1 in ~1500)
L. Dumont, BPAC, May 2008
Release and Surveillance Confirmed Positive 10000 1000 100 4 / 6039 662 7 / 8282 312 845 329 445 6 / 6438 932 865 185 119 200 121 231 ARC 10 ARC Diversion 4mL Diversion 8mL 1-Bottle Test PsPrt PsPrt Surv.
Irish Aph Surv.
Irish BC Welsh Aph 2-Bottle Test Surv.
Welsh BC
Contaminated Platelet Units Often Escape Bacterial Culture Detection*
• 100% bacterial screening of platelet concentrates (PC) introduced by Irish Blood Transfusion Service in 2005 • Overall Sensitivity of Screening: 29.2% (CI: 19.4-39.1%) – All PCs tested prior to release on day after manufacture • 0.08% (35/43,220) positive – PCs false negative at release • Expired PCs retested, 0.22% (18/8282) positive • Repeat test of PCs in stock on day 4 of storage to re-qualify, 0.12% (4/3320) positive *W.G. Murphy
et al
, Vox Sanguinis 2008 (e-pub)
● “It is unthinkable that a manufacturer of other intravenous medications could eschew reasonable methods to eradicate possible contamination on the basis that only organisms of questionable clinical significance persisted in the preparations infused.
” ● “It is also unthinkable that end users of intravenous agents would be asked to check sterility before use, …….” ● “It is apparent to us that bacterial testing, whether early or late, lacks sufficient robustness …… as the method of choice once a method of eradication of adequate proven safety and utility is available.
”
W.G. Murphy et al Vox Sanguinis 2008 95:13-19
TAS RISK - SUMMARY
• Current screening methods of for platelets inadequate.
the are bacterial clearly • Considerable TAS risk remains, particularly for recipients of platelets, as ~1 in 1500 PC units may not be identified as containing bacteria.
• PI has shown efficacy in killing bacteria that may be present in PCs.
FRACTIONATED PLASMA PROTEINS
It is particularly relevant that there has been no reported transmissions of HIV, HBV or HCV by a pathogen inactivated plasma derivative since 1987.
Should we not apply PI technology to all blood products, including platelets, RBCs and plasma?
BIOPHARMACEUTICAL PATHOGEN REDUCTION/CLEARANCE TECHNOLOGY
Nanofiltration Affinity Purification Solvent-Detergent AHF Heat Low pH UV/Propiolactone Fractionation Pasteurization 1985 2000
LESSONS LEARNED FROM PI OF PLASMA PROTEINS
• Efficacy of biological products is maintained.
• Toxicity not usually encountered.
• Immunogenicity seldom encountered.
• Viral safety clearly can be achieved.
PATHOGEN-INACTIVATED BLOOD COMPONENTS
•
Goal
: Eliminate transmission of viruses, bacteria and parasites (known and unknown) •
Secondary Specific Drivers
: - Bacteria - Parasites - CMV - GvHD
ADDITIONAL CONSIDERATIONS APPLICABLE TO BLOOD COMPONENTS
• Eliminating infectivity from components is more difficult than eliminating infectivity from derivatives: – Higher viral concentration – More proteins to consider – Cells (platelets, RBCs) more fragile – Some microbes not sensitive to PI (i.e. prions).
• Validation studies need to examine a wider range of variables than encountered in the protein setting.
• GMP requirements are yet to be enunciated.
PATHOGEN INACTIVATION METHODOLOGY
• Solvent-detergent (SD plasma) • Methylene blue (MB, for plasma) • Psoralens (S-59, Amotosalen) • Riboflavin (vitamin B2) • S-303 (for RBCs, Amustaline) • Other dyes • UVC (under investigation for platelets)
Disrupting Nucleic Acid
• • • • • •
REASONS FOR SLOW ACCEPTANCE OF PI
Perceived current safety of the volunteer blood supply.
No single method to treat all components.
Success of surveillance and screening in dealing with emerging pathogens, even if delayed.
Inability of current technologies to inactivate all agents (small, non-encapsulated viruses, spores, high-titer viremia, and prions). Risks from the residual unknown agents?
Cost/Benefit ratio acceptable?
CAUTIONS REGARDING PATHOGEN INACTIVATION TECHNOLOGY
• Each technology is different: – Chemical/biological characteristics; – Spectrum of pathogen reduction; – Activity for specific pathogens -“log reduction;” – Activity in specific components; – Adducts and metabolites; – Lack of knowledge of the profile of adverse reactions (toxicity).
FUTURE SCREENING TEST DEVELOPMENT
• Babesia testing?
• Chagas’ disease testing ?
• Dengue (DFV) virus testing?
• Malaria testing?
• Point-of-use bacterial testing?
• Chikungunya virus?
U.S.TRANSFUSION-ASSOCIATED BABESIA MORTALITY
• Human babesiosis is a protozoal zoonotic illness that is transmitted by
Ixodes scapularis
ticks.
• Various babesia species can infect vertebrate hosts.
• 70 Babesia TTIs have been reported in North America since 1979, most in the last decade.
• Ten TTI babesia deaths since 1997, nine within the last 3 years.
• Babesia would be readily killed by PI.
Gubernot DM et al. Clin Infect Dis 2009; 48: 25-30.
MALARIA RISK MANAGEMENT
• The parasites are readily killed by PI.
• Would avoid malaria donor deferrals.
• Travel deferrals for malaria avoided.
• Testing strategy implementation will be avoided altogether.
AVOIDANCE OF BACTERIAL TESTING
• Current PI strategy would do nothing to prevent TAS due to contaminated RBCs.
• PI impact on platelet viability is minimal.
• Could result in significant cost savings.
• Increased safety of platelets.
• Platelet inventory could be released earlier.
AVOIDANCE OF NEW MICROBIOLOGICAL THREATS
• Good likelihood of killing most emerging agents.
• Fewer donor deferrals will be required.
• Test avoidance (WNV, Syphilis, anti-HBc).
• No impact on prions!
• Would eliminate the need for Chagas’ Disease testing.
• N.B. This would apply only if RBC or whole blood PI also becomes available.
IMPACT ON CONTINUED NEED FOR UNIVERSAL LEUKOREDUCTION
• With implementation of PI, there would be no need to γ-irradiate blood components.
• Thus there would be no need for blood irradiators in Blood Centres.
• May however not address the HLA alloimmunization risk of non-LR platelets.
IMPACT OF PI ON CMV TESTING
• Current CMV TTI risk ~2%.
• Reduced risk of CMV transmission to susceptible patients.
• When PI becomes universal, CMV testing would no longer be required.
• Avoids a special inventory for “CMV-safe” products.
IMPACT ON DONOR TESTING
• Simplified donor questionnaire.
• MSM would no longer be an issue.
• Less time would be needed to screen donors.
WHAT PI WILL PROBABLY NOT DO
• Will not reduce TRALI risk.* • Will not reduce prion risk associated vCJD travel deferrals.
or • Will not prevent the occurrence of transfusion errors.
*The use of SD-plasma will likely reduce the TRALI risk with its use (Prowse C. Transfus Med Rev 2009; 23: 124-133).
__________
Pathogen Inactivation
Making Decisions About New Technologies
CONSENSUS CONFERENCE ON PATHOGEN INACTIVATION
Sponsors: Canadian Blood Services Héma Québec (BEST Collaborative) March 29-30, 2007
STEERING COMMITTEE Morris Blajchman, MD, FRCPC (Chair)
Canadian Blood Services
Gilles Delage MD
Héma-Québec
Jaroslav Vostal, MD, PhD
CBER, FDA
Dana Devine, PhD
Canadian Blood Services
Sunny (Walter) Dzik, MD
Massachusetts General Hospital
Stephen Wagner, PhD
American Red Cross
Kathryn Webert, MD, FRCPC
McMaster University
Heather Hume, MD
Canadian Blood Services
Harvey G. Klein, MD
NIH (Panel Chair)
Lorna Williamson, MD, FRCP
University of Cambridge NHS UK Blood and Transplant
BEST Collaborative, Chair
CONSENSUS CONFERENCE PROCESS
March 29 – 30, 2007 • Topic Identified.
• Steering Committee crafts questions, identifies speakers, and appoints panel.
• Speakers outline key issues (day 1).
• Panel deliberates and produces statement.
• Draft Statement presented (day 2).
• Panel refines Consensus Statement.
QUESTIONS POSED TO THE PANEL ─ 1 1. Implementation criteria
: Is the current risk of transfusion-transmitted diseases acceptable in relation to other risks of transfusions? a) If so, under what new circumstances should pathogen inactivation be implemented?
b) Should the criteria be the same for RBCs, platelets, and FFP?
c) Should different criteria be used for certain patient populations?
2. Licensing requirements:
What minimum acceptable safety and efficacy criteria should be put into place for the pre-approval assessment of pathogen inactivated products? Specifically: a) What criteria should govern acceptable toxicology standards and how should they be assessed? b) What type of post-marketing surveillance should be required (if any) with the implementation of pathogen inactivated blood components.
3.
Blood Service and Clinical issues:
For pathogen inactivation technologies that have been approved by the regulatory authorities, what implications should be considered prior to their widespread adoption? Also, if pathogen inactivated components differ in function from non-pathogen inactivated equivalent products, how should this information be disseminated?
QUESTIONS POSED TO THE PANEL ─ 2 4. Risk management issues:
If pathogen inactivation were to be implemented for all components; in principle, what criteria would allow: a) The relaxation of any current donor deferral/exclusion policies?
b) The cessation of any currently undertaken screening tests? c) A decision not to implement new screening tests for agents susceptible to pathogen inactivation? Should multiple inventories be considered for each component and if yes how should allocation be decided?
5. Cost-benefit impact:
How should the costs/benefits of pathogen inactivation be assessed? Should these be aligned with other blood safety interventions and/or other health care interventions?
6. Research requirements:
implemented?
What other information, considerations, and research-related questions would need to be answered in order to decide whether/when a particular pathogen inactivation procedure should be
CONSENSUS PANEL Harvey G. Klein - Panel Chair
National Institutes of Health
David Anderson
(Hematologist) QE II Health Sciences Centre Halifax, NS
Marie-Josée Bernard
(Ethicist) CRIR Montreal, QC
Ritchard Cable
(Transfusionist) American Red Cross Blood Services Farmington, CT
William Carey
(Blood Recipient) Owen Sound, ON
Jeffrey S. Hoch
(Health Economist) St. Michael’s Hospital Toronto, ON
Nancy Robitaille
(Hematologist–Paeds) CHU St. Justine Montreal, QC
Marco L.A. Sivilotti
(Toxicologist) Queen’s University Kingston, ON
Fiona Smaill
(Infectious Disease Expert) McMaster University Health Sciences Hamilton, ON
CONSENSUS CONFERENCE SPEAKERS TOPIC SPEAKER 1. Microbiological reasons for considering PI in Transfusion Medicine.
Dr. H. Alter Dr. R. Dodd 2. Biochemical and biological mechanisms of PI methodology.
3. Toxicology issues relating to the PI of blood products: Impact on recipients. Dr. J. Chapman
CONSENSUS CONFERENCE SPEAKERS TOPIC SPEAKER 4. Efficacy of PI FFP.
Dr. C. Prowse 5. Efficacy of PI platelets. 6. Clinical experience with PI platelets.
7. Efficacy of PI RBCs.
8. Immunogenic issues with the use of PI RBCs.
Dr. S. Slichter Dr. J-P Cazenave Dr. J. AuBuchon Dr. G. Garratty
CONSENSUS CONFERENCE SPEAKERS TOPIC SPEAKER 9. The place of PI in the Transfusion Medicine Dr. W. Dzik overall risk-benefit ratio.
10. Regulatory issues: FDA perspective.
11. Regulatory Issues: European community perspective.
12. Regulatory Issues: Canadian perspective.
Dr. J. Vostal Dr. M. Heiden Dr. P. Ganz
CONSENSUS CONFERENCE SPEAKERS TOPIC SPEAKER Dr. M. Kuehnert 13. Public health aspect of residual risks relating to transfusions.
14. Economic issues. Cost benefits of PI in relation to other aspects of transfusion medicine.
Dr. B. Custer 15. Overview of newer PI technologies. Dr. S. Wagner
PRIMARY PUBLICATIONS
1. Preliminary Panel Report: Klein HG et al.
Vox Sanguinis 2007; 93: 179-182.
2. Final Panel Report: Klein HG et al.
Transfusion 2007; 47: 2338-2347.
3. Proceedings: Webert KE et al. Transfusion
Medicine Reviews 2008; 22: 1-34.
SECONDARY PUBLICATIONS
4.
Editorial: McCullough J.
Pathogen inactivation: A new paradigm for blood safety. Transfusion 2007; 47: 2180-2184.
5.
Editorial: Sher GD, Devine DV. The consensus development process in transfusion medicine: Does it add value?
Transfusion 2007; 47: 2176-2179.
6.
Alter HJ.
Pathogen reduction: A precautionary principle paradigm. Transfusion Medicine Reviews 2008; 22: 97-102
Alter HJ: “I was in that packed hotel ballroom in 1994 when Dr. David Kessler urged blood banks to develop NAT for routine donor screening. His talk raised eyebrows and great skepticism; but because of his position of authority, it drove the system……, and resulted in the remarkably rapid development of practical NAT assays that have been an enormous addition to blood safety.”
NEW PI PARADIGM WOULD:
• Replace current paradigm which has been mostly reactive.
• Proactive paradigm would potentially deal with emerging microbiological agents (probably most).
• Would prevent GvHD.
● Research should be encouraged to identify rare and long-term consequences of the transfusion of PI products.
Chronically transfused patient populations might serve as an ideal surveillance population to identify long-term toxicities of pathogen inactivated products.
PI RESEARCH OPPORTUNITIES : SUMMARY OF AN NHLBI WORKSHOP*
• Took place in July 2008.
• 30 invited participants and speakers.
• The focus was non-microbiological research questions.
• The idea was to identify research opportunities of various PI methods for platelets, RBCs, plasma and whole blood.
• Currently available PI technologies were reviewed.
*Klein HG et al. Transfusion 2009: On line
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2.
3.
4.
5.
6.
GENERAL RESEARCH QUESTIONS POSTED
What are the appropriate methods for the clinical evaluation of candidate PI technologies?
Are there potential novel and/or improved methods for evaluating the efficacy of PI?
How will PI affect the risk of acute and delayed transfusion reactions such as fever, hemolysis, anaphylaxis, TRALI or other acute lung injury?
Will new technologies render blood functionally
leukoreduced
and will they be equivalent to the gamma irradiation currently being used in preventing GVHD?
How will PI affect recipient immune responsiveness and/or tolerance?
Will certain patient populations be at particular risk, or alternatively derive special benefit from PI treated components?
NOVEL PI TECHNOLOGY DEVELOPMENTS
• Methods that can be used for the PI of whole blood.
• Alternative approaches to the inactivation of cellular blood products using new chemicals and/or new technologies.
• Investigations into novel methods that can be used specifically for the PI of RBCs.
• PI technology that will have both an improved safety profile and ability to maintain in vivo function, recovery, and survival.
EXPLORING ADVERSE EVENTS RELATED TO PI TECHNOLOGIES
• Mechanism(s) of the adverse side effects that have been observed during clinical testing of PI-treated PLTs.
Particular priority should be given to investigations of possible pulmonary toxicity.
The development of suitable animal models is also encouraged.
• The development of a database capturing information on adverse events detected during clinical trials.
• Further evaluation of the distribution and metabolism of different additives and derivatives.
• Identification and use of improved models, including animal models, for the comparative assessment of PI treated cell/protein safety and efficacy.
SAFETY AND EFFICACY
• Evaluation of the effect of PI treatment on the noninfectious complications of transfusion.
• Exploration of study designs that will allow the evaluation of the safety and efficacy of PI products used in trauma patients.
• Exploration of study designs that will allow the evaluation of the safety and efficacy of PI products used in vulnerable populations.
• Evaluation of the impact of residual photoactive chemicals after PI treatment on blood product toxicity and stability in vivo.
• Investigation of methods that will facilitate the removal and/or inactivation of pathologic prion proteins.
• Investigation of the effects of PI treatment on component viability and shelf life.
• Investigations into the effects of PI on component immunogenicity and on the immunomodulatory effects of transfused blood products .
HEALTH ECONOMICS AND COST-EFFECTIVENESS
• Development of analytical methods to determine what costs can be prevented by the adoption of PI technology and an assessment of the resources likely to be saved by the prevention of adverse events.
• Assessing the cost utility (cost-effectiveness) of PI technology from the societal perspective including budget impact analysis.
• Investigate and model the impact of PI implementation on blood availability.
• Development of cost-effective methods for PI that would be particularly suitable and effective for use in developing countries.
• The development of risk-benefit assessments using simulation modeling.
PATHOGEN INACTIVATION: THE NEW PARADIGM IN TRANSFUSION MEDICINE
PANEL RESPONSES TO QUESTIONS*
*Klein HG et al. Vox Sanguinis 2007; 93:179-182.
Klein et al. Transfusion 2007; 47:2338-2347.
1. Is the current risk of transfusion-transmitted diseases acceptable in relation to other risks of transfusions?
● The panel recognizes that emergent transfusion-transmitted pathogens have been detected at an increasing rate since the HIV epidemic.
● The panel recognizes that such risks require a proactive approach in accordance with the precautionary principle.
● The risk of bacterial contamination has been reported as high as 1 in 2,000 platelet transfusions prior to the implementation of bacterial testing of platelets.
● Hemovigilance data suggest that these risks are in aggregate substantially lower than the current non-infectious risks of transfusion; such as acute hemolysis, delayed hemolysis, and TRALI.
2. What minimum acceptable safety and efficacy criteria should be put into place for the pre-approval assessment of pathogen inactivated products?
● The Panel recognizes that the different regulatory authorities have each established their own standard approaches to these assessments. PI technologies that target nucleic acid should undergo careful scrutiny to assess the potential for genotoxicity, carcinogenocity, reproductive toxicity, and germ-line toxicity. The Panel strongly recommends the use of adequately powered well-designed randomized clinical trials using clinically relevant endpoints.
● The Panel encourages the harmonization of approaches and sharing of data among the various regulatory agencies.
● The panel recommends the sharing of hemovigilance data across jurisdictions.
3. For pathogen inactivation technologies that have been approved by the regulatory authorities, what implications should be considered prior to their widespread adoption?
● Consultation with appropriate patient and physician stakeholder groups as well as hospital physician and transfusion groups.
● Inventory management, particularly at the time of crossover from the current to the new technology.
● The PI procedure should be introduced as a pilot project in one geographic area to work out logistical, environmental and occupational health issues before it is implemented more widely.
4. If pathogen inactivation were to be implemented for all components; in principle, what criteria would allow changes in deferral and screening test policies:
● Following the implementation of PI for all components existing procedures could be modified in order to reduce donor deferrals. However, the rationale for PI implementation should be independent of these considerations.
● The regulatory agencies and blood collectors should review the donor screening questionnaire to eliminate or modify questions that are thought to be of marginal value such as tattooing and certain travel deferrals.
● Cessation of screening agents that are not readily transmissible by transfusion, e.g., T. pallidum (syphilis); agents sensitive to PI and for which redundant safety measures are in place, such as CMV, HTLV, and anti-HBc; and agents that are exquisitely sensitive to PI and for which the current tests have poor specificity and sensitivity, such as bacteria.
5. How should the costs/benefits of pathogen inactivation be assessed?
● Implementation of PI should not be based solely or even primarily on the results of an economic analysis; as most costs are currently unknown and the benefits are difficult to quantify.
● Costs and benefits should be assessed using a societal perspective, examining both direct and indirect costs in accordance with published recommendations.
Sensitivity analysis, at a bare minimum, should focus on variations in price and effectiveness.
6. What other information, considerations, and research-related questions would need to be answered in order to decide whether /when a particular pathogen inactivation procedure should be implemented?
● Consideration be given to robust governmental support for a large scale investment in developing an integrated PI technology for all blood components.
● Mathematical modeling should be used to develop credible scenarios for the unknown pathogen risk; for example, what are the “break-even” threshold conditions and are they consistent with a worst case scenario.
This model could be used in economic analysis of candidate PI technologies to support decisions about investment for the research agenda