High Throughput Donor Plasma NAT Screening Assay Applied to Acute HIV Detection in a Public

Health Setting

December 5, 2007

Josh Goldsmith, Ph.D.National Genetics Institute, a LabCorp Company

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Presentation Outline Current challenges with acute HIV screening NGI PCR and pooling methods A prospective clinical study to validate the

method for plasma donor screening Acute HIV demonstration project with SFDPH

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Challenges in the Implementation of PCR-Based Acute HIV Screening Programs Availability of validated methods Availability of “off-the-shelf” methods Availability of cost-effective methods Availability of scalable methods where broad-

based screening programs are envisioned

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National Genetics Institute (NGI) Profile A provider of automated, sensitive PCR methods for infectious

disease testing Offers assays for HIV, HAV, HBV, HCV, and other infectious

agents Screens the majority of US supply of source plasma for infectious

agents (~8M donations/year) with pools of 512 samples A licensed clinical laboratory and approved by FDA CBER to

perform pooled nucleic acid testing for donor plasma screening A subsidiary of LabCorp with access to blood draw centers and

courier networks throughout the US

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Dilution Profile

Analytical Sensitivity of UltraQual HIV-1 PCR

Probit Analysis

99% detection cut-off = 5

copies/ml

512 x 5 copies/ml

= 2560 copies/ml

(minimum titer in individual sample to have

99% probability of detection in 512 sample pool

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NGI Pooling and Pool Resolution Process Launch Executable File

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NGI Prospective Clinical StudyStudy Objectives

To demonstrate HIV-1 PCR testing of pooled plasma samples can accurately detect HIV-1 infection

To validate plasma pooling and pool resolution process for pools ≤ 512 individual samples

To determine the clinical sensitivity and specificity of the pooling and pool resolution process

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NGI Prospective Clinical StudyStudy Design

342,729 plasma donations collected from ~48,000 donors donating at 33 donor centers over a 3.5 months

Informed consent obtained for HIV Ab and RT-PCR testing

Individual plasma samples tested for HIV Ab (Bio-Rad) and HIV-1 p24 antigen (Coulter) and HIV RNA (NGI)

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NGI Prospective Clinical StudyPool Numbers and Sizes

Summary of Master Pools and Donations Tested During Clinical Study Period

Master pools Donations

n (%) n (%) Min Max Mean SD

Tested during study 703 (100.00) 345,320 (100.00) 233 510 491 17

No results 6 ( 0.85) 2,591 ( 0.75) 233 509 432 110

Analyzed for study 697 ( 99.15) 342,729 ( 99.25) 388 510 492 14

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NGI Prospective Clinical Study Results

Rate of HIV-1 RT-PCR Positivity Found in Plasma Donations by Master Pool Testing and the Resolution Testing Algorithm

HIV RT-PCR positive

N N %

All donations in clinical trial 342,729 18 0.0053

Donations from repeat donors 316,099 15 0.0047

Donations from new donors 26,630 3

HIV-1 Ab negative donations 342,684 10 0.0029

Donations from repeat donors 316,065 10 0.0031

Donations from new donors 26,619 0

HIV-1 Ab negative, p24 Ag negative donations

342,674 6 0.0018

Donations from repeat donors 316,055 6 0.0019

Donations from new donors 26,619 0

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NGI Prospective Clinical Study ResultsClinical Specificity-false positives

samples HIV-1 PCR (-)Clinical Specificity = samples HIV-1 (-)*

* HIV-1 (-) defined as samples for which test results for HIV-1 PCR,

HIV EIA, and/or p24 antigen are negative

342,668 HIV-1 PCR (-)Clinical Specificity = 342,668 HIV-1 (-)* (HIV-1 PCR)

= 100%**

**95% CI 99.6-100%

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NGI Prospective Clinical Study ResultsClinical Sensitivity-false negatives

samples HIV-1 PCR (+)Clinical Sensitivity =

samples HIV-1 (+)*

* HIV-1 (+) defined as subjects for which test results for HIV-1

PCR, HIV EIA, and/or p24 antigen are positive

18 HIV-1 PCR (+)Clinical Sensitivity = (HIV-1 PCR) 18 HIV-1 (+)*

= 100%**

**95% CI 83.3-100%

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NGI Prospective Clinical StudyStudy Conclusions HIV-1 PCR testing of pooled plasma samples

can accurately detect HIV-1 infection Plasma pooling and pool resolution process for

pools ≤ 512 individual samples is validated Clinical sensitivity and specificity of the pooling

and pool resolution process is high NGI received FDA biologics license from FDA (CBER) for screening of donated plasma based

on the study results

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San Francisco Department of Public Health (SFDPH) Demonstration Project - Study Overview

Patient samples were collected from the SFDPH city clinics and community based services over a 5-month period

Samples were screened by SFDPH for HIV antibodies with standard EIA (Vironostika) or rapid HIV antibody tests (Orasure Technologies)

HIV Ab (-) samples were picked up by LabCorp couriers and transported to NGI for testing

NAT positive samples were identified in pools of 64 samples and confirmed by individual NAT

All patients identified as positive were counseled and referred for HIV care and follow-up by SFDPH.

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San Francisco Department of Public Health (SFDPH) Demonstration ProjectStudy Results

NAT testing identified 5 additional HIV-positive samples increasing the

overall HIV detection rate by 12% to 3.1%.

Total Positive (+) Negative (-) Positivity Rate

Patient Samples Collected 1536

HIV Ab Testing 1536 43 1493 2.8%

HIV NAT Testing 1444 5 1439 0.3%

HIV Ab and NAT Testing 1536 48 3.1%

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Conclusions A pooled specimen HIV PCR assay has been validated for large-

scale plasma donor screening involving pools of up to 512 samples

The method was applied to the detection of acute HIV in a public health setting with SFDPH

As this method is routinely used for screening millions of blood plasma donations per year, opportunities exist to implement broad-based acute HIV screening programs in a highly cost-effective fashion

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Acknowledgements

San Francisco Department of Public Health

Jeff Klausner MD, MPH

Nicola Zetola, Ph.D.

Katherine Ahrens, MPH

National Genetics Institute/LabCorp

Mark Richardson, CLSpMB Richard Smith, Ph.D.

Hawazin Faruki, Ph.D.