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Dendreon Launches A New Vaccine Protocol For Men With Metastateic Hormone
Refractory PCa With Gleason Sums < 7 (September 2003)
Encouraged by
establishing "proof of principle" in their recently completed protocol,
D9901, Dendreon has opened a new protocol with similar design but limited
to men whose Gleason sum < 7. The D9901 protocol utilized the
Dendreon product "Provenge", a fusion protein combining GMCSF with
prostatic acid phosphatase to create a vaccine, administered in three
intravenous applications, and designed to stimulate a dendritic cell
mediated immune response against prostate cancer cells (Discussed in PCa
Commentary, December 2002). Treatment effectiveness was evident, but only
in the subset of patients with Gleason sums of < 7 (n=75) of which
50 men had received "Provenge" and 25 received a placebo. A major study
end points was time to disease progression (TTP). Progression developed at
a similar rate in both the treated and control groups (during which 50% of
each group experienced progression) until about 8 - 10 weeks at which time
a trend of better outcome favored the treatment group. This initial period
of superimposed decline preceding the separation of the TTP graphic curves
for the two groups was thought to result from the time required for the
development of an effective immune response. The percent remaining free
from progression in the treated v. control groups at 6 months was 34% v.
4%, at 12 months l0% v. 0%, and at 18 months 6.7% v. 0%. The numbers are
small, but encouraging, and hence the new protocol, D9902B.
D9902B is now open
for enrollment and is aiming for 275 participants. TTP progression and
time to first occurrence of cancer related pain are the primary endpoints.
As in the prior study, the randomization is 2:1 favoring treatment. For
study entry contact Drs. Tia Higano (U of W) or John Corman (Virginia
Mason Clinic).
The sister study of
similar design (P11) remains open for enrollment. This study accepts
patients experiencing their first PSA failure post radical prostatectomy
and who are free of metastatic disease on imaging studies. For patient
entry contact either Dr. Higano, Dr. Corman, or Dr. Jack West, Swedish
Cancer Institute.
BOTTOM LINE:
Enrollment of men into these early vaccine trials is a vital first step
toward the development of effective vaccine therapy for prostate cancer.
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