Originally Published IVD Technology March 2002
Industry News
CBER releases guidance on nucleic acid plasma-screening tests
Richard Park
FDA's Center for Biologics Evaluation and Research (CBER) has recently released a draft guidance on the use of nucleic acid tests to screen plasma for HIV and hepatitis C. Entitled "Use of Nucleic Acid Tests on Pooled Samples from Source Plasma Donors to Adequately and Appropriately Reduce the Risk of Transmission of HIV-1 and HCV," the guidance presents background information and updates on the development of nucleic acid testing as a screening tool for plasma.
The draft guidance was released in early December 2001 at a CBER-sponsored workshop on emerging technologies and the application of nucleic acid testing to blood-borne pathogens. According to CBER, the document is intended to inform establishments engaged in the manufacture of source plasma that the agency
has approved nucleic acid tests (NAT) to identify human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) in source plasma donations, and that we believe that a licensed nucleic acid test to identify HIV and HCV in source plasma donations, when available, should be used to adequately and appropriately reduce the risk of transmission of these communicable diseases.
Industry analysts point out that the draft guidance may result in the elimination of p24 antigen testing. According to the draft guidance, such other types of testing may not be as reliable as nucleic acid testing, and may be unnecessary once nucleic acid testing is being used.
"The availability of nucleic acid testing to identify HIV and HCV will change the testing protocol that should be used to adequately and appropriately reduce the risk of transmission of those diseases," the guidance states. "We believe that when nucleic acid testing is available, it may no longer be appropriate to rely solely on other tests for HIV-1 and HCV, such as those for antibody and HIV-1 p24 antigen; those tests, without nucleic acid testing, may not be adequate and appropriate. FDA may also consider not requiring HIV-1 p24 testing of source plasma if establishments implement NATs that are more sensitive than HIV-1 p24 tests."
Beyond this change, however, industry analysts believe the draft guidance will have little impact on the IVD industry as a whole.
"The guidance is primarily for the plasma industry, not for the whole-blood industry," says Larry Mimms, vice president for product development at Gen-Probe Inc. (San Diego). "So it's not really going to affect the way whole blood is being tested today. The guidance will have little or no effect on companies such as ours. Essentially, the guidance reiterates what is already being done and basically restates FDA's position."
The workshop at which the guidance was released focused on issues regarding the implementation of nucleic acid testing to screen blood and plasma donors for HIV, HCV, and HBV, as well as the manufacturing pools for HAV and parvovirus B19. Topics covered at the workshop included an examination of international developments and regulatory issues relating to the implementation of minipool and single-unit nucleic acid testing; standardization and quality assurance for nucleic acid methods; industry experience with minipool nucleic acid testing for donor screening and in-process testing of plasma pools; potential replacement of current tests by nucleic acid testing; and emerging issues and challenges, including new pathogens and technologies.
"It is hoped that using nucleic acid methods to test individual units rather than to test minipools will eventually be technologically possible and cost-effective," says Edward Tabor, MD, associate director for medical affairs at CBER. "This would make nucleic acid screening far more sensitive. Nevertheless, it was not clear from presentations at the workshop exactly how long it will be before single-unit nucleic acid testing is available, and it appeared from these presentations that a cost-effective single-unit nucleic acid test is still not available."
A copy of the draft guidance is available via CBER's Web site at http://www.fda.gov/cber/guidelines.htm. Transcripts of the workshop are also available at http://www.fda.gov/cber/minutes/workshop-min.htm.
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