Guide for the Assessment of Clotting Factor Concentrates

More documents

Recommendations

Info

Inventory holdInventory hold is the holding of plasma in (frozen) storage before it is processed into concentrates. Aplasma donation is held until testing of the donor ensures that the donation was not collected whilethe donor was in the window period of disease. The use of inventory hold pending qualification of plasmadonors further enhances safety and is an attractive, although not mandatory, feature. This measure isgenerally only possible for source plasma, as apheresis donors can donate more frequently which mayresult in more donations during the infectious window period. The particular features of an inventoryhold vary across the organizations which practice it. It is most effective when donations which are notre-tested are not used, whether the donor returns or not. This is not always the case, and the particularfeatures of a plasma supplier’s inventory hold should be kept in mind in assessing the relative safetymerits of paid and unpaid plasma sources.Ensuring the safety of raw materialsDonor selection procedures that exclude high-risk donors, combined with serological screening of plasmadonations are the mainstay of ensuring safe raw material for the fractionation process. The safety ofthe raw material can only be ensured by the fractionator through the use of suppliers that excludehigh-risk donors and use good quality viral screening tests. Further guidance on how regulatoryauthorities can make certain of the safety of raw material used for blood products is provided inSections 2, 3, and 4. Some fractionators may purchase plasma from the open or so-called “spot” plasmamarket, rather than obtain it from their own centres or from centres subscribing to their own standards.The use of such “spot” plasma will not be subject to the same level of safety and regulatory control asthe use plasma from well-accredited centres, and authorities should not consider using products manufacturedfrom this type of plasma.Viral reduction processesThere are two types of viral reduction processes: inactivation (viral kill) and removal of virus throughpurification of protein. Viral elimination procedures in the manufacturing process have had the greatestimpact on enhancing the safety of hemophilia treatment products. While all the components of theblood safety chain described in this guide are required for product safety, manufacturing processes canhave an especially significant role. For example, solvent-detergent treatment made pooled hemophiliatreatment products safe from hepatitis C before the introduction of testing for the virus increased thesafety of normal blood transfusion and single-donor cryoprecipitate from HCV transmission. Authoritiestasked with assessing which measures are essential for ensuring safe products – as opposed to thosewhich, while enhancing safety, are not essential – need to keep in mind the features of plasma derivatives,such as hemophilia products, relative to the hospital products of mainstream blood banking.While donor selection and screening of donations, combined with appropriate NAT testing (andinventory hold where it can be achieved), have significantly reduced the risk of blood-borne virusesentering the fractionation pool, we must presume that any plasma pool for fractionation may containlevels of virus capable of transmitting infection. The inclusion, in the fractionation process, of one ormore steps with validated capability to inactivate and/or remove relevant viruses, primarilyenveloped viruses (HIV, HBV, and HCV), results in plasma products that are essentially free from riskof these viruses. However, current inactivation and removal processes are less effective for nonenvelopedviruses (mainly HAV and parvovirus B19, and the concern can be extended to “unknown”viruses and infectious agents also).6 Guide for the Assessment of Clotting Factor Concentrates
There are a number of different viral reduction methods available, including solvent-detergent, heattreatment (pasteurization, dry-heat, or steam heat), and nanofiltration. The advantages and limitationsof these are outlined in Table 2, page 8.Failures in testing, processing, or critical quality systems are more likely to result in the release of abatch of product with increased risk of infection than any fundamental deficiency in process design orcompetence. Because of the importance of viral elimination in the ultimate safety of plasma products,there is no room for failure in the process steps upon which viral elimination depends. Process validation,and those systems at the heart of good manufacturing practices — traceability, segregation of productmanufacturing steps to avoid cross-contamination, training, documentation, change control, deviationreporting — are the keys to the reliable manufacture of safe, effective plasma products.Non-enveloped virusesCurrent viral inactivation and/or removal steps are effective for enveloped viruses but less effective fornon-enveloped viruses. While some viral elimination steps, notably nanofiltration, have been shown tooffer at least a partial reduction of the viral burden from non-enveloped viruses during product manufacture,other strategies, particularly vaccination when possible (for HAV, for example) of people receivingplasma concentrates on a lifelong basis, should be used. For known non-enveloped viruses, severalmanufacturers have established schemes involving limit testing of the plasma pool using NAT inwhich a maximum level of viral contamination, rather than an absolute elimination, is the aim. In theabsence of validated viral reduction in-process steps, this offers probably the current best generalapproach for reducing the viral burden of the plasma pool and, therefore, for reducing the transmissionpotential for viruses tested using this methodology.Variant Creutzfeldt-Jakob disease (vCJD)Experiments with different animal species indicated that the diseases known as transmissible spongiformencephalopathies (TSEs) are transmissible through blood, plasma, and plasma fractions. These experimentsindicated that a considerable portion of the infectivity in blood is actually found in the plasma, and iscarried into plasma fractions when the plasma is processed into therapeutic products. However,depending on the fraction studied and the manufacturing technique used, much of the infectivity isremoved or cleared from the therapeutic product as a result of the manufacturing process.At least some of the animal studies have been confirmed in humans as four recipients of blood or redcells from donors who developed a human TSE — variant Creutzfeldt-Jakob disease (vCJD) 1 — havealso been infected with the disease. Therefore, this illness is a blood safety risk and is addressedthrough the same combination of measures which are used to minimize the risk of viral transmission.The only donor selection measure which is currently possible for minimizing the risk of donors incubatingthe disease entering the plasma pool is the deferral of individuals who have been exposed to BSEthrough travel or residence in a country where the disease has entered the food chain. These deferralmeasures have been introduced by a number of countries. The main target of these policies has beentravel or residence in the United Kingdom during the period when BSE was entering the human foodchain in that county, but some countries have also included deferral of donors with a history of travel andresidence in other countries with a minor BSE epidemic.1 CJD is the human form of bovine spongiform encephalopathy (BSE), a disease in cattle which has affected animals in theU.K. and the European continent and which is thought to have entered the human food chain through the consumption ofcontaminated meat products. For current information on the prevalence of BSE in different countries go to www.oie.intGuide for the Assessment of Clotting Factor Concentrates 7
Page 1: GUIDE FOR THE ASSESSMENTOF CLOTTING
Page 5 and 6: INTRODUCTIONSelecting therapeutic p
Page 7 and 8: SECTION 1FACTORS AFFECTING THE QUAL
Page 9: and authorities need to assess each
Page 13 and 14: Treatment Advantages Points to cons
Page 15: measures may have only limited bene
Page 18 and 19: • FDA draft guidelines• FDA ins
Page 20 and 21: Common strengths of U.S. & EU regul
Page 22 and 23: • Audit potential suppliers who m
Page 24 and 25: on HCV reactivity in product sample
Page 26 and 27: Basic requirementsThere are a numbe
Page 28 and 29: treatment, and therefore samples sh
Page 30 and 31: EvaluationSome of the consideration
Page 32 and 33: Figure 2: Production of cryoprecipi
Page 34 and 35: Some measures which should be inclu
Page 37 and 38: APPENDIX 1REGISTRY OF CLOTTING FACT
Page 39 and 40: TABLE 1A: SEROLOGIC TESTS ON INDIVI
Page 41 and 42: TABLE 2. FACTOR VIII CONCENTRATES M
Page 43 and 44: BRAND COMPANY SITE OF MANU-FACTUREP
Page 45 and 46: TABLE 7: OTHER CLOTTING FACTOR CONC
Page 47 and 48: APPENDIX 2MODEL PRODUCT ASSESSMENT
Page 49: (D) STABILITY AND SHELF LIFEInclude
Page 52 and 53: Nucleic acid testing (NAT): Testing
Page 56: World Federation of Hemophilia1425

Guide for the Assessment of Clotting Factor Concentrates

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?