GVAX Immunotherapy For Prostate Cancer Induces A Broad, Patient-Specific Antibody Response
- From: Matti Narkia <mna@xxxxxxxx>
- Date: Wed, 18 Apr 2007 20:28:20 +0300
Cell Genesys Reports GVAX Immunotherapy For Prostate Cancer Induces
A Broad, Patient-Specific Antibody Response
Article Date: 18 Apr 2007
Cell Genesys, Inc. (Nasdaq: CEGE) today reported immune response
data from two previously conducted Phase 2 clinical trials of GVAX
immunotherapy for prostate cancer. Evaluation of antibody responses
in patients with advanced prostate cancer from these studies shows
that the GVAX cell-based immunotherapy induces antibody responses
to a broad array of prostate cancer- associated antigens, including
some not previously known to be associated with prostate cancer. In
addition, the antibody responses to this non patient- specific
product were predominantly patient-specific and unique from patient
to patient, indicating the potential advantage of a cell-based
multi-antigen product such as GVAX to generate the broadest and
most relevant immune response. Serological analysis of gene
expression (SEREX) technology was also used to identify target
antigens involved in response to the immunotherapy. More than 148
proteins to which antibody responses were induced were identified
and many of these proteins had not been identified previously as
prostate cancer-associated antigens. These findings were presented
today by Dr. Thomas Harding and colleagues from Cell Genesys at the
annual meeting of the American Association for Clinical Research
being held in Los Angeles, CA.
GVAX immunotherapy for prostate cancer is currently being studied
both as a single agent and in combination with docetaxel
chemotherapy in two Phase 3 clinical trials targeted to enroll
approximately 1200 patients with metastatic hormone-refractory
prostate cancer (HRPC). This ongoing Phase 3 program is supported
by the median survival results from two, independent, multi-center
Phase 2 clinical trials. Cell Genesys recently reported final,
updated results from its second multi-center Phase 2 trial of GVAX
immunotherapy for prostate cancer, which evaluated escalating doses
of the immunotherapy in 80 patients with metastatic hormone-
refractory prostate cancer (HRPC). Additional follow-up of the 22
patients who received the dose that is comparable to that being
employed in the company's ongoing Phase 3 program revealed that
their median survival is 35.0 months. Four patients have withdrawn
consent to further follow-up and thus were censored in the
analysis. The company also has previously reported final median
survival results from its first multi-center Phase 2 trial of GVAX
immunotherapy for prostate cancer in 34 patients with metastatic
HRPC that showed an overall median survival of 26.2 months. The
survival results from the two, independent multi-center Phase 2
clinical trials compare favorably to the previously published
median survival of 18.9 months for metastatic hormone-refractory
prostate cancer patients treated with Taxotere(R) (docetaxel)
chemotherapy plus prednisone, the current standard of care for
these patients. The company's ongoing Phase 3 program is designed
to confirm this potential survival benefit of GVAX immunotherapy
for prostate cancer.
"The immune response data reported today provide added support for
the concept that a whole-cell immunotherapy, such as GVAX
immunotherapy for prostate cancer, is an ideal multi-antigen source
that is capable of eliciting an immune response to a broad array of
tumor-associated antigens," stated Peter K. Working, Ph.D., senior
vice president of Research and Development at Cell Genesys. "That
the majority of antibody responses are unique to individual
patients is further evidence that the non patient-specific format
of GVAX immunotherapies is capable of inducing unique, patient-
specific immune responses. Moreover, the fact that many of these
antigens have not before been associated with prostate cancer,
further suggests that a multivalent antigen immunotherapy like GVAX
immunotherapy may provide the best potential for inducing an
effective anti-tumor immune response, especially for heterogeneous
cancers such as prostate cancer."
Evidence of patient-specific immune responses associated with non
patient- specific GVAX immunotherapy products has also been
reported in other cancers. In August 2004, the company reported on
data published in the Journal of Experimental Medicine from a Phase
1 clinical trial of GVAX immunotherapy for pancreatic cancer that
provided evidence that patient-specific immune responses can be
generated following treatment with this non patient-specific
product. The article described detailed analyses of the immune
response to the immunotherapy in three out of 14 patients who were
long-term survivors and who also demonstrated strong T cell
responses to mesothelin, a tumor- associated protein found in the
majority of pancreatic cancers and in the GVAX immunotherapy for
pancreatic cancer cells. The specificity of the T cell response to
mesothelin was shown to be unique to each responding patient
providing further scientific proof-of-concept for the company's
GVAX immunotherapy strategy.
GVAX immunotherapy for prostate cancer is comprised of two prostate
cancer cell lines that have been modified to secrete GM-CSF
(granulocyte-macrophage colony stimulating factor), an immune
stimulatory hormone, and irradiated for safety. GVAX cancer
immunotherapy for prostate cancer is being developed as a non
patient-specific, "off-the-shelf" pharmaceutical product. ...
Excerpted from
Cell Genesys Reports GVAX Immunotherapy For Prostate Cancer Induces
A Broad, Patient-Specific Antibody Response
<http://www.medicalnewstoday.com/medicalnews.php?newsid=68097&nfid=crss>
--
Matti Narkia
.
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