Panel to Review GP160 Vaccine Candidate: Report of the Meeting

development, Dr. Corey said. For instance, it might make sense to
use a "more natural" vaccine candidate--perhaps a gpl60 or gpl20
product carrying sugar groups that more closely resemble those
found on HIV itself (as produced on experimental vaccines being
made in mammalian cell systems)--than to continue with a
glycoprotein vaccine whose sugar groups are acquired in nonmammalian cells and thus are less like those found on envelope
proteins in clinical isolates of HIV. Moreover, possibly other
components of HIV rather than the envelope proteins in the gpl60
and gpl20 products will prove more useful in eliciting a
protective response, particularly from cytotoxic T cells in the
host, he said.
MicroGeneSys CEO raises objections. Mr. Franklin Volvovitz,
the CEO of MicroGeneSys, objected to the fact that Dr. Corey and
not Dr. Redfield of WRAIR had been asked to summarize the
latter's data. Dr. Volvovitz also criticized Dr. Corey's
interpretation of certain gpl60 studies, asserting that the
presentations were based on selection of data rather than being
"open and objective...without bias."
For example, Dr. Volvovitz and Dr. Corey appear to disagree
over animal model studies (involving SCID mice) undertaken to
determine (by indirect means) whether gpl60 can confer protective
immunity on human recipients. Dr. Corey pointed to results
indicating first a protection and the a loss of protection; Mr.
Volvovitz said that efforts to confirm these early studies
showing partial protection with combination gpl60 vaccines were
unsuccessful. He described studies that showed no protection in
the SCID-hu mouse model with either the MicroGeneSys gpl60
vaccine alone or in combination with other vaccines.
Mr. Volvovitz also raised several other issues--some
technical, but others more general in nature. Among issues from
the latter category, he posed a complex question that other
meeting participants still face: What is the relative importance
of the humoral and cellular immune responses in individuals who
are fighting HIV infections and what impact will vaccine
treatments have on them? Although discussions were abbreviated,
he was promised that these issues would be addressed more fully
at a follow-up meeting.
AIDS VACCINE DEVELOPMENT OPTIONS
With so many AIDS vaccine candidates currently being
developed, it is vital to evaluate which ones are ready to go
forward for serious clinical evaluation, and which others need
additional basic development or perhaps are ready to be
discarded. "Vaccines live in the world of science," said Dr. Dani
Bolognesi of Duke University Medical Center in Durham, North
Carolina. Because there are both scientific "gaps" and
"opportunities," it is appropriate to "take stock...and select
the best way to proceed."