[Letter to Tema Luft from Anthony Fauci]

DEPARTMENT OF HEALTH & HUMAN SERVICES

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National Institutes of Health
Bethesda, Maryland 20892
Building:31
Room:7A03
(301) 496- 2263
October 15, 1991
Ms. Tema Luft
8115 Conduit Road
Baltimore, Maryland 21234
Dear Ms. Luft:
Thank you for your letter of September 16, 1991 which expressed concern about
trials of candidate vaccines sponsored by the National Institute of Allergy
and Infectious Diseases (NIAID). Let me begin by commenting on our current
knowledge of the safety and efficacy of recombinant gpl60 (rgpl60) candidate
vaccines.
The study recently published by Redfield and colleagues was designed to
evaluate whether rgpl60 manufactured by MicroGeneSys was safe and immunogenic
in individuals with CD4+ T cell counts greater than 400. The results showed
that there were no apparent detrimental effects during the 10 month period of
study and that a subset of the patients "responded" to the candidate vaccine
in that they had increased levels of both antibodies and cells that recognize
gpl60. Further, these "responders" maintained slightly higher CD4+ T cells
counts over the 10 month study period.
In spite of press reports, these results, while promising, do not mean that
rgpl60 was effective. The individual rate of decline of CD4+ T cells is
highly variable. It is quite possible that infected individuals who
"responded" to rgpl60 in this study experienced a slower decline in CD4t T
cells for reasons that are unrelated to rgpl60. More specifically, it is
possible that a response to the vaccine (or perhaps to any antigen) may simply
be an indication of which individuals possess a more functional immune system
and might therefore, without. any therapy, progress more slowly relative co
__those who can not respond to an antigen. While these studies represent an
- important first step in using rgpl60 therapeutically in infected individuals,
we can not at this time conclude that rgpl60 affords a clinical benefit The
- safety of rgpl60 beyond this initial observation period is also not known
N - This is quite important because long term harm is a real possibility.
___ Appropriately controlled studies designed to answer these questions are now
underway at Walter Reed and in the NIAID-sponsored AIDS Clinical Trials uroups
-ou (ACTG).
0
__ - The NIAID is supporting vaccine evaluations through two mechanisms - the AIDS
___ Vaccine Evaluation Units (AVEUs) and the AIDS Clinical Trials Group (ACTC,
The AVEUs have responsibility for examining the safety and immunogenicitw of
__-_ candidate vaccines in uninfected individuals. The results obtained by te