San Francisco: Phase I Trial of Bucast (Castanospermine Analog) Recruiting

A new trial in San Francisco will begin the human testing of
Bucast, an anti-HIV compound which has been studied in
laboratory tests and in animals for several years. This phase
I study seeks 40 to 60 volunteers, who must have a T-helper
count over 500, and be willing to spend some time at HIVCare
at St. Francis Memorial Hospital -- the only site where this
early study is being conducted.

Bucast (also called 6-0-butanoylcastanospermine) is a
chemical derivative of castanospermine, an antiviral found in
an Australian tree, Castanospermum australe. Bucast is at
least several times more potent as an antiviral than the
natural castanospermine in laboratory cell cultures.

Bucast (and castanospermine) are glycosylation inhibitors --
they interfere with an enzyme required by HIV for processing
glycoproteins (chemicals composed of both proteins and
sugars). Laboratory studies suggest that these glycosylation
inhibitors will make the virus more susceptible to attack by
the immune system, and also prevent the formation of syncytia
-- giant cells formed when T-helper cells join together
abnormally and die. (A different glycosylation inhibitor,
butyl-DNJ, is already in human trials.)

Bucast has shown antiviral activity in animals, as well as in
laboratory cultures. Also, castanospermine has been found to
be synergistic with AZT in laboratory cell cultures, meaning
that the two work better together than would be expected by
adding their separate antiviral activities.

The Trial

There will be two parts of this trial, which will be placebo
controlled. Part A will test a single dose of bucast. Part B
will test daily doses given for 14 days. The drug is taken
orally. The aim of this study is to find the maximum
tolerated dose.

Persons can volunteer for either part A, or part B, or for
both. Part A requires one 36-hour stay in the hospital, and
daily visits of up to two hours each morning, for the
following seven days. Part B requires 36 hours in the
hospital, daily visits for 13 days, then another 36 hours in
the hospital.

Volunteers should realize that they cannot expect personal
medical benefit from participation in a phase I study; the
main motive for enrolling in this trial will be altruistic.
Because no medical benefit is expected, participants who
complete the study will receive monetary compensation for
their time. And they will not be excluded from phase II
trials of Bucast.

Comment

There is always a risk in a clinical trial which gives a new
drug to people for the first time. This risk is minimized by
careful animal studies, in which animals are given much
larger doses than any human volunteers will receive; the FDA
requires these studies before the drug can be given to
humans.

This trial is important, because of the great need for new
AIDS treatments.

For More Information

For more information, call Mark Bowers, Client Coordinator,
HIVCare, St. Francis Memorial Hospital, 415/353-6215.