Anti-HBc Testing and Donor Reentry Results of a Pilot Study

1. Anti-HBc Testing and Donor ReentryResults of a Pilot Study Susan L. Stramer, Ph.D. American Red Cross Blood Products Advisory Committee Meeting Nov 4, 2005 (update from Oct 21, 2004 meeting) In collaboration with: National Genetics Institute and Abbott Laboratories

2. Anti-HBc TestingBackground • Historical/present RR rates range from 0.4%-1.6% • False positivity high • 25-87% reported • dependent on specificity of test used • No confirmatory/supplemental tests • 1X anti-HBc RR may donate again; impact of RR notification • 2X anti-HBc RR deferred • Historical number of deferred donors who lack other deferral codes • > 200,000 April 1991-Dec 2003 • > 500,000 nationwide since Feb 1987

3. Anti-HBc TestingBackground • Can an algorithm be validated to reenter deferred donors who are falsely anti-HBc reactive? • If so, what would be the yield of reentry? • Unanimous support from BPAC (Oct 21, 2004) for validation of a reentry algorithm • Test a follow up sample by: • Highly sensitive HBV DNA assay (<10 copies/mL) • “Alternate” anti-HBc assay having improved specificity • (and HBsAg) • Above tests must be negative

4. Anti-HBc TestingProject Yield Based on Current 2X Reactive Algorithm • 3.9 million donors (6.5 million donations) from 2000 studied • 0.64% anti-HBc overall repeat reactive rate • 1.37% from FT/0.24% from RPT donors • 75% 1X anti-HBc reactive donors became 2X on next donation (plus another 13% over next 3 years) • 88% FT and 38% RPT • Anti-HBc reentry algorithms projected to have higher yields if a “different” test is introduced; i.e., blood system converts to a different method

5. Reactive Rates for Anti-HBc (Ortho)through July 2005 Percent Mean RR by NTL (FY2006) NTL Percent N NTL Percent N NTL Percent N DET 0.28 289,547 CHA 0.42 227,840 PHL 0.41 241,895 STL 0.32 216,655 POR 0.57 166,533 Mean IR = 0.54 Mean RR = 0.39 Total N = 1,142,470 ’99 ’97 ’98 ’05 ’02 ’00 ’96 ’03 ’01 ’04 Month (1995-2005)

6. Anti-HBc Results from Hema-Quebec ---------Ortho--------------- --------Abbott PRISM*--------- *without reductant

7. Anti-HBc RR Donation PCR Testing (NGI)Pilot Study • 3000 anti-HBc RR unlinked donations selected in 2001 for further testing by NAT (HBV PCR at NGI) • Surplus NAT samples in PPTs (limit contamination) • Criterion for inclusion was nonreactive by all other test methods • No preselection of 1X versus 2X anti-HBc RRs • 3000 chosen to allow a large enough sample size to include significant numbers of 2X RR donors • 23.6% of ARC donors over a comparable time were 2X anti-HBc RR • Approx 708 of 3000 were 2X anti-HBc RR

8. Anti-HBc RR Donation PCR Testing (NGI)Pilot Study • Samples tested individually by HBV DNA • UltraQual 8-rxn, 0.2-mL input • Reactivity in any of 8 tests = Positive • Sensitivity 9 IU/mL • Conversion 3.44 copies/IU = 31 copies/mL • 19/3000 (0.63%) samples reactive • 11 < 100 copies/mL • Average of 1.7 per 8 reactions reactive • 8 with viral loads of 100-500 copies/mL; 287.5 mean • Average of 4.75 per 8 reactions reactive

9. Parameter REDS ARC Roche Sample dates 1991-95 2001 2002-03 No. tested 395 3,000 3,956 No. DNA-pos 4 19 14 Rate: Calc’ted Direct Direct per HBc-pos 0.24% 0.63% 0.35% per tx unit 1:49,000 1:37,000 1:54,000 Viral Load (copies/mL) all < 100 68% < 100 93% MP- NAT (-) HBV DNA in “anti-HBc-only” units

10. Anti-HBc RR Donation PCR Testing (NGI)Pilot Study • 3000 samples tested by Abbott PRISM anti-HBcore using licensed lots • Study initiated following qualification of PPTs on the PRISM and availability of “licensed” lots • Assumption is that 19 HBV DNA positives would be PRISM anti-HBc reactive • Anti-HBc nonreactive/DNA negative samples would represent “eligible donors” for reentry • Testing completed • Anti-HBc reactives investigated for anti-HBc IgM anti-HBs as samples volume allows • Study ongoing

11. PRISM HBcore NGI HBV UltraQual 1000 * Mean S/CO = 0.14 (range 0.02-0.49); S/CO < 1.00 = Reactive ** 7 Samples PCR Negative; PRISM HBcore QNS

13. Summary and Conclusions • Preliminary data indicate feasibility of anti-HBc reentry algorithm • All 19 HBV DNA-positive samples detected as reactive by Abbott PRISM anti-HBcore ChLIA • All 19 strongly anti-HBc reactive • Mean S/CO = 0.14 (range 0.02-0.49) • Yield of reentry dependent on prior assay • 25% for Ortho => Ortho (1X=>2X) • 21% for Ortho => PRISM (pilot study) • 40% for Ortho => PRISM (Hema-Quebec) • ?? for Corzyme (prior Abbott) => PRISM

14. Subsequent Studies • Approx 5000 deferred donors (2X, with anti-HBc as only deferral criterion and HBV DNA negative) from Oct 04-Sept 05 invited to provide follow-up sample under NGI’s HBV IND • Testing: HBV DNA (NGI; 5 copy/mL sens), HBsAg, anti-HBc (Ortho; PRISM pending), anti-HBs • Study will convert to Roche’s IND using FDA proposed anti-HBc reentry algorithm • Licensed PRISM anti-HBcore and HBsAg; nonreactives tested by investigational Roche HBV DNA protocol • 10% eligible donors have provided a follow up sample • 66% “past” HBV infection; leaves 44% for reentry • Yield dependent on PRISM anti-HBcore reactivity, but due to low participation rate, maximum is 4.4%

16. Reactive = 2994 (79%) Nonreactive = 782 (21%) HBV DNA Positives 

18. Anti-HBc RR Units Tested by HBV PCR (NGI) • anti-HBc RR donations tested by HBV PCR (N = 31,914) • HBV PCR Pos N = 2,669 (8.4%) • 1,002 (38%) HBsAg Confirmed Pos • 1,667 (62% or 5.2% total) HBsAg NR