CBER Update on status of West Nile virus test, lot release and validation panel development Indira Hewlett, Ph.D CBER/FDA Blood Products Advisory Committee Meeting June 19, 2003

CBER Previous FDA Actions March BPAC discussion of FDA proposal for : - clinical study design - unit and donor management - FDA efforts in panel development

CBER FDA Actions – con’t Study design for test sensitivity Repository specimens, including transfusion and community acquired WNV illness Positive cases from prospective studies Seroconversion panels

CBER Clinical sensitivity Testing a common set of pedigreed specimens by all candidate investigational tests to determine whether assays have equivalent sensitivity Testing all reactive specimens identified during IND studies by all manufacturer’s assays

CBER Analytical sensitivity FDA’s current standard for WNV NAT assays is 100 copies/ml for the individual donation Standard may be revised as assay sensitivity improves and additional data on viremia and infectivity become available in future studies

CBER Unit and donor management FDA proposed foll: scheme for donor and unit management - Reactive invest. NAT results on the individual donation could be confirmed by F/U testing with invest. NAT, alternate NAT and IgM - If F/U sample is positive by invest. NAT or alt. NAT, donor remains deferred for an additional 28 days - Donor may be eligible for reinstatement if F/U sample prior to 28 days is NAT-ve, and IgM +ve

CBER Progress on test development Multiple IND studies are in progress Two manufacturers have publicly acknowledged existing INDs: Gen-Probe Inc. and Roche Molecular Systems Inc. IND tests are based on NAT using pooled or individual samples Intended use for whole blood, blood components, source plasma, bone marrow, cord blood, hematopoietic progenitor cells, tissue and organ donors

CBER Progress on test development Expected start date for testing is early July, 2003 All samples will be collected under approved IRBs with necessary informed consent Analytical sensitivity of IND tests is comparable and between 5-15 copies/ml

CBER Procleix ® WNV Assay TMA-based assay for screening blood donations for West Nile virus RNA Uses existing instrument platform as Gen-Probe’s licensed NAT blood screening assay –Procleix Semi-automated System (eSAS) currently used with Procleix HIV-1/HCV Assay Uses existing formulations as much as possible

CBER Procleix ® WNV Assay Analytical sensitivity: 95% detection rate between 7-15 copies/ml Specificity in pre-clinical studies evaluated by testing 1180 blood donations No cross reactivity to other blood borne viruses –HTLV, HIV-1/-2, HCV, HBV, HGV, Rubella, HAV, CMV, EBV, HCV, Parvo B19 No cross reactivity to other flaviviruses: Dengue (1-4), Yellow Fever Virus, and St. Louis Encephalitis virus

CBER WNV IND Two Phased Clinical Protocols Phase I: Retrospective prevalence study –89,000 archived American Red Cross samples from 6 high incidence areas during the 2002 season Phase II: Prospective donor screening –Voluntary donations of whole blood and source plasma at 25 testing sites : IDT or pools (site dependent) –Nation-wide testing expected to begin by July 1, 2003

CBER Procleix WNV Assay Early Testing Contingency Plan Upon WNV regional outbreak, samples will be shipped and prospective testing initiated at Phase I ARC site(s) –Current testing capability limited Archiving samples from ~June 1st onward –Testing of samples based on regional prevalence Contingent on IRB-approval, WNV informed consent in place

CBER Roche WNV NAT: Pre-clinical Performance Studies PCR-based screening assay for use with pooled samples Analytical sensitivity between 5-7 copies/ml No cross-reactivity seen with non-WNV microorganisms: HTLV-I/II, HIV, HCV, HBV, CMV, HSV, HAV, HPV, Varicella, Adenovirus Clinical specificity random volunteer samples from WNV low- and high- prevalence areas

CBER FDA Panel Development Efforts Lot release panel for licensure and post- market surveillance of NAT and IgM tests Qualification panel for evaluation of relative sensitivities of investigational NAT and IgM assays

CBER FDA NAT Panels FDA NY99 and FDA-Hu2002 isolates characterized by g enetic sequencing Viral infectivity determination –PFUdetermined at both FDA and NY Dept. of Health Laboratories, and by cytopathic assays at FDA RNA concentration measurements –Fluorescence and Optical density determination –TaqMan Final panel specifications are being established through collaborative studies

CBER PFU Results on FDA Isolates At FDA –NY99 (CDC Flamingo Isolate) 10 8 /mL –HuWNV /mL At NY State Dept. of Health –NY99 (CDC Flamingo Isolate) 5.5 x10 7 /mL –HuWNV x10 6 /mL

CBER Viral Titer Determination Copy/mL SampleLab 1Lab 2Lab 3Lab 4Average HuWNV HuWNV ND10 6 HuWNV ND10 2 HuWNV o C/2hr 10 7 NY NY ND10 6 NY ND10 2 NY o C/2hr

CBER Correlation between Copy/mL and PFU/mL SampleAv. copyPFU HuWNV /mL HuWNV 60 o C/2 hr NY /mL NY99 60 o C/2 hr

CBER At least 100 pedigreed clinical specimens –RNA positive only –IgM positive only –Dual RNA and IgM positive FDA also recommends that all reactive specimens identified in IND clinical trials be made available to all manufacturers through sharing of samples FDA Plan for Qualification Panel

CBER FDA IgM panel Panel will consist of clinical specimens containing varying titers of antibodies to WNV and some members that are also NAT positive Panel will be evaluated in collaborative studies using various candidate IgM assays Specifications for NAT and IgM panels will be established based on results of collaborative studies

CBER Summary Both NY99 and FDA-Hu2002 stocks have a viral titer of copies/mL PFU titers at both NY State Dept of Health Laboratory and at FDA were three logs lower than copy numbers Heat treatment virus results in loss of infectivity and 2 to 3 log reduction in copy number determined by TaqMan

CBER Acknowledgements Gen-Probe, Inc Roche Molecular Systems, Inc. Maria Rios, CBER, FDA Robert Lanciotti, CDC Laura Kramer, New York Department of Health