Prostate Cancer Vaccines more Effective with Hormone Therapy
PHILADELPHIA, July 10, 2008– Among patients with
castration-resistant prostate cancer, the addition of hormone
therapy following vaccine treatment improved overall survival
compared with either treatment alone or when the vaccine followed
hormone treatment, according to recent data published in the July
15 http://clincancerres.aacrjournals.org Clinical Cancer
Research, a journal of the American Association for Cancer
Research.
Philip M. Arlen, M.D., director of the Clinical Research Group for
the Laboratory of Tumor Immunology and Biology, Center for Cancer
Research, at the National Cancer Institute, said the findings have
important implications for guiding treatment decisions for prostate
cancer patients.
“Vaccines, if and when they are approved, can be safely and
effectively combined with other therapies, including
hormones,” said Arlen. “There appears to be an
advantage in overall survival."
Arlen and colleagues enrolled 42 patients who had
castration-resistant prostate cancer. These patients were randomly
assigned to receive either a poxvirus-based prostate-specific
antigen vaccine or hormone therapy with nilutamide. At progression,
patients received the other therapy and continued to receive their
original therapy.
For all the patients enrolled in the study, the three-year survival
probability was 71 percent and the median overall survival was 4.4
years. Patients randomized to the vaccine had a three-year survival
probability of 81 percent and an overall survival of 5.1 years,
while patients taking nilutamide had a three-year survival
probability of 62 percent and an overall survival of 3.4
years.
Of the 42 patients in the study, 12 patients who were originally
assigned to vaccine switched to nilutamide plus vaccine and eight
patients who were originally assigned to nilutamide switched to
vaccine plus hormone, due to rising levels of prostate-specific
antigen with no evidence of metastasis. For patients who received
vaccine and then nilutamide, the three-year survival probability
was 100 percent with a median overall survival of 6.2 years. For
patients who switched to the vaccine after hormone, the three-year
survival probability was 75 percent with a median overall survival
of 3.7 years.
Arlen said the hormone therapy in combination with the vaccine
works in two ways.
“By using hormone therapy in prostate cancer you can help
enhance your T-cell response to where the cancer is in the prostate
gland, and you are also more likely to achieve a better immune
response,” said Arlen.
Building on the results of this phase II study, researchers have
developed another generation of this vaccine by adding molecules
which boost T-cell responses.
Based on the current pace of vaccine research overall, Arlen
predicts that men with prostate cancer could potentially see an
effective, new treatment vaccine within the next several
years.
“Phase II trials such as this one are adding to our
knowledge, and other phase III trials are getting ready to publish
their data,” said Arlen. “If the phase II data hold up
in phase III trials, we could see a new treatment vaccine within a
few years.” # # #
The mission of the American Association for Cancer Research is to
prevent and cure cancer. Founded in 1907, AACR is the world’s
oldest and largest professional organization dedicated to advancing
cancer research. The membership includes more than 28,000 basic,
translational and clinical researchers; health care professionals;
and cancer survivors and advocates in the United States and 80
other countries. AACR marshals the full spectrum of expertise from
the cancer community to accelerate progress in the prevention,
diagnosis and treatment of cancer through high-quality scientific
and educational programs. It funds innovative, meritorious research
grants. The AACR Annual Meeting attracts more than 17,000
participants who share the latest discoveries and developments in
the field. Special conferences throughout the year present novel
data across a wide variety of topics in cancer research, treatment
and patient care. AACR publishes five major peer-reviewed journals:
Cancer Research; Clinical Cancer Research; Molecular Cancer
Therapeutics; Molecular Cancer Research; and Cancer Epidemiology,
Biomarkers & Prevention. Its most recent publication and its
sixth major journal, Cancer Prevention Research, is dedicated
exclusively to cancer prevention, from preclinical research to
clinical trials. The AACR also publishes CR, a magazine for cancer
survivors and their families, patient advocates, physicians and
scientists. CR provides a forum for sharing essential,
evidence-based information and perspectives on progress in cancer
research, survivorship and advocacy.
Media Contact:
Jeremy Moore
267-646-0557
Jeremy.moore@aacr.org
Posted: July 2008
