Department of Immunology and Molecular Pathology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, United Kingdom. p.delves@ucl.ac.uk
The heterodimeric 'pregnancy-specific' hormone human chorionic gonadotropin (hCG) has been used as the basis for a contraceptive vaccine. More recently, the observation that hCG, particularly in the form of the beta-chain expressed in the absence of alpha-chain, is aberrantly expressed in a number of different tumors has opened up a second potential application for such vaccines. Drawbacks of the currently available vaccines are that they are either relatively weakly immunogenic or that they induce antibodies that cross-react with human leuteinizing hormone (hLH). We have explored the possibility of creating mutated versions of the hCG beta-chain with improved immunologic properties.
PMID: 17049720 [PubMed - indexed for MEDLINE]
Monoclonal antibodies to two epitopes
of beta-human chorionic gonadotropin for the treatment of cancer.
Curr
Opin Mol Ther. 2003 Apr;5(2):156-60.
Iversen PL, Mourich DV, Moulton
HM.
Source: AVI BioPharma Inc., 4575 SW Research Way, Corvallis, OR 97333,
USA. piversen@avibio.com
. Vaccination of patients with the therapeutic peptide Avicine
(CTP37; AVI BioPharma Inc/SuperGen Inc), that contains 37 amino acids from the carboxyl
terminus (CTP37; AVI BioPharma Inc/SuperGen Inc) of hCG, can result in two distinct
antibody responses to separate epitopes within the peptide. . These observations provide a compelling rationale for the
development of two human monoclonal antibodies (mAbs), one for each of the epitopes
within the 37 amino acid peptide region of hCG. Two such human mAbs, both exhibiting
a high degree of specificity and affinity have been prepared using XenoMouse technology.
These mAbs may prove useful in multiple clinical settings for the treatment of various
cancers. Treatment options may include passive immunotherapy with both mAbs, mixed
passive supplement to active specific immunotherapy with Avicine and conjugation
of the mAbs with radioisotopes or cytotoxic drugs. The requirement for dual mAb therapy
is consistent with current trends in the development of complex, non-toxic therapies
for cancer.
December 7, 2001 -AVI BioPharma, Inc.
announced today that its therapeutic cancer vaccine, AVICINE, provided a substantial
survival benefit in patients with pancreatic cancer.
In a 55-patient Phase
II study, patients were treated with AVICINE alone or in combination with gemcitabine
(Gemzar®, Eli Lilly & Co.). The randomized trial was designed to evaluate the
safety and effectiveness of these treatments, and was conducted at seven centers
across the United States.
One-year survival data for the AVICINE alone group
is similar to that reported for Gemzar. However, patients had no significant vaccine-related
side effects, in contrast to the often severe side effects associated with Gemzar.
Importantly, one-year survival of 30% for the patient group treated with AVICINE
plus Gemzar was significantly better than either treatment alone. Patients continue
to be treated and followed, with 22 months the longest patient survival to date.
These results provide support for previous observations that AVICINE is an effective
cancer-fighting agent.
Principal Investigator John Marshall, M.D. of Lombardi
Cancer Center, Georgetown University, Washington, DC, commented, "These results
compare very favorably to the best published results of chemotherapy alone in this
condition. The results in the combination group are the best I've observed with this
difficult cancer. The findings provide ample support for AVI's ongoing AVICINE cancer
vaccine program."
In addition to survival, study endpoints included specific
antibody responses to the vaccine and the influence of chemotherapy on antibody response.
Patients treated with chemotherapy and vaccine together had nearly equivalent antibody
responses to vaccination, indicating that gemcitabine had little or no impact on
pancreatic cancer patients' ability to respond to a new immune challenge.
"We
are very encouraged by the results of this study. Our preliminary data, presented
at the annual meeting of the American Society of Oncology (ASCO) in May, 2001, suggested
that AVICINE is as effective as traditional chemotherapy, but without the devastating
side effects associated with that treatment," said.
David H. Mason, Jr.,
M.D., AVI's Senior Vice President of Clinical Development and Regulatory Affairs.
"We are particularly pleased at this time to report that one-year survival data
suggest an advantage to the addition of AVICINE to traditional chemotherapy. That
patients continue in the study, some beyond 18-20 months, bodes well for potential
long term benefits to patients from treatment with our immunotherapeutic agent."
Dr.
Mason added, "Having reviewed the complete data from the study, we are encouraged
that Gemzar did not seem to have a negative influence on patients' immune response
to cancer vaccine treatment. Patients can undergo combination treatment without concern
that this chemotherapy will reduce vaccine effectiveness."
AVICINE is
a therapeutic cancer vaccine that elicits a highly specific immune response to human
chorionic gonadoptropin (hCG), a cancer-associated oncofetal protein. The vaccine
blocks hCG's function, which is to facilitate tumor growth, angiogenesis, invasion
and immunosuppression. The most common side effects of AVICINE are mild reactions
at the site of injection. Six completed clinical trials have shown that it is considerably
less toxic than traditional chemotherapy.
....AVICINE™.....has completed a
Phase II trial in pancreatic cancer and is in a Phase III pivotal trial in colorectal
cancer. More information about AVI is available on the Company's website at http://www.avibio.com.
AVI BioPharma Initiates Multicenter
Phase II Clinical Trial of AVICINE in Pancreatic Cancer-PORTLAND, Oregon--(BW
HealthWire)--June 2, 1999
John Marshall, M.D. of Georgetown University To
Serve As Lead Principal Investigator
AVI BIOPHARMA INC. today announced that
it will initiate a multicenter Phase II clinical trial of the company's therapeutic
cancer vaccine, AVICINE(TM), in pancreatic cancer patients on June 15, 1999. The
randomized trial, involving at least 50 patients, is being conducted at seven centers
nationwide and is designed to evaluate the safety and efficacy of AVICINE alone and
the potential synergistic effects of AVICINE in combination with Eli Lilly &
Co.'s gemcitabine chemotherapy (Gemzar(TM)). This protocol was filed with the FDA
on April 23, 1999 and marks two advances in AVI's AVICINE development strategy. The
study will include the new AVICINE formulation containing an additional peptide domain,
which the company believes will enhance the effectiveness of the vaccine. Moreover,
this study marks the first trial in which the vaccine will be administered with a
chemotherapeutic agent. John Marshall, M.D. of Georgetown University will serve as
lead principal investigator for the study, which will be managed by Premier Research
Worldwide, a clinical research organization located in Philadelphia, PA.
This
trial follows Phase Ib/II clinical trials of AVICINE, which were designed to evaluate
safety and efficacy in pancreatic cancer patients. The evidence from these studies
suggested that AVICINE is a well-tolerated vaccine without systemic toxicity. The
median survival in the ten pancreatic cancer patients treated with AVICINE was 33
weeks without drug-related toxic side effects, compared to the 23 week median historical
survival for this disease for patients treated with chemotherapy.
Denis Burger,
Ph.D., President and CEO of AVI BioPharma, stated, "The initiation of Phase
II trials of AVICINE in pancreatic cancer represents a significant milestone for
the company, and is the result of extensive clinical efforts to demonstrate the applicability
of our unique technology to a broad range of cancers. As such, we have made great
strides in our development activities to support our premise that the peptides of
the hCG hormone are the key components in a cancer vaccine, which may result in survival
benefits even in the most aggressive tumors. Extensive analysis of our clinical data
from 77 patients with advanced colorectal cancer showed that a dual antibody response
to hCG peptides correlated with nearly a doubling of survival benefits compared to
chemotherapy. By including a second hCG peptide in AVICINE in this protocol, we believe
that most patients will produce the advantageous dual antibody response. Because
pancreatic cancer is so aggressive, the combination of AVICINE and gemcitabine may
provide additional benefits beyond either therapy alone."
Dr. Marshall
stated, "We have been impressed with the AVICINE data from AVI's Phase II study
in colorectal cancer where statistically significant survival benefits correlated
with a dual antibody response. As a result, we are very pleased to be involved in
this study, especially since AVICINE appears to work through a unique mechanism,
distinctly different from gemcitabine chemotherapy. Given the vaccine's excellent
safety profile and lack of systemic toxicity, we are encouraged that AVICINE alone
may provide survival benefits over chemotherapy. Moreover, the evaluation of AVICINE
plus gemcitabine may also provide evidence for the inclusion of the vaccine in combination
therapy."
Cancer of the pancreas is the fifth leading cause of cancer
death in the United States. This year an estimated 28,000 people in the U.S. will
die from this disease. Currently, fewer than 10% of patients live more than 1 year
after diagnosis and fewer than 50% will survive 6 months.
AVICINE, a therapeutic
cancer vaccine, is AVI BioPharma's lead product candidate. AVICINE elicits a highly
specific immune response to the human hormone and growth factor hCG, a cancer-associated
oncofetal protein. AVICINE is essentially a non-toxic immunotherapy and has been
evaluated in five clinical trials. To date, 174 patients have been treated. Early
studies have provided evidence of objective tumor responses and apparent survival
benefits in patients who have failed conventional therapy.
AVI BioPharma Inc. Announces Additional
Data From Multi-Center Phase II Study of AVICINE in Advanced Colorectal Cancer.
PORTLAND, Ore.--(BW HealthWire)--May 26, 1999.
New Data Suggests Increased
Survival Linked To Dual Antibody Response -
AVI BIOPHARMA INC.....today
announced analysis of additional clinical data from its multi-center Phase II clinical
trial of AVICINE(TM), a therapeutic cancer vaccine, in advanced colorectal cancer.
This data builds upon previously announced results gathered from a two-year clinical
trial of AVICINE in 77 patients with metastatic colorectal cancer. Overall, 51 of
the 77 patients demonstrated an immune response to human chorionic gonadotropin (hCG),
with a median survival of 42 weeks. The additional data suggests that patients who
responded to both targets (epitopes) of the hCG peptide (CTP-37) experienced a median
survival of approximately 65 weeks, compared to a median survival rate of 39 weeks
for Pharmacia-Upjohn's FDA approved drug, Camptosar(R).
Intensive investigation
over the past six months found that the vaccine peptide is composed of two epitopes,
one of which is dominant. The dominant epitope orchestrates a single antibody response
in approximately half of the patients. The balance of the patients responded to both
epitopes (dual response). This dual response correlated with a statistically significant
survival benefit (65 weeks) compared to a single antibody response (35 weeks), or
standard chemotherapy with Camptosar. The new data support the addition of a second
hCG peptide to the vaccine formulation in order to modulate immunological dominance.
Overall, these data suggest that patient survival is linked to hCG antibody response,
with dual responses providing a significantly more favorable outcome than responses
to a single epitope. The inclusion of a second hCG peptide in the Company's AVICINE
formulation is expected to increase immunological response to multiple epitopes resulting
in improved patient survival.
Denis R. Burger, Ph.D. AVI's President and CEO,
stated, "Based upon the new data, we are encouraged to go one step further in
our development efforts in order to make AVICINE a more potent vaccine. Specifically,
we have formulated a new vaccine that contains an additional hCG peptide domain,
referred to as the loop peptide. The addition of the loop peptide modulates the dominance
of the past formulation, resulting in a strong, balanced antibody response. Simply
by adding an additional peptide we are able to force the immune system into responding
to multiple epitopes, which leads to improved survival. The FDA has reviewed the
new AVICINE formulation and AVI plans to use the new formulation in our upcoming
clinical trials."
AVICINE, a therapeutic cancer vaccine, is AVI BioPharma's
lead product candidate. AVICINE elicits a highly specific immune response to the
human hormone and growth factor hCG, a cancer-associated oncofetal protein. AVICINE
is essentially a non-toxic immunotherapy and has been evaluated in five clinical
trials. To date, 174 patients have been treated. Early studies have provided evidence
of objective tumor responses and apparent survival benefits in patients who have
failed conventional therapy.
Avicine Data Published in Oncology
Reports
PORTLAND, Ore.--(BW HealthWire)--Jan. 26, 1999--AVI BIOPHARMA
INC. today announced the publication of a review article, "Human chorionic gonadotropin
as a target for cancer vaccines," in Oncology Reports (5: 7-17, 1999)
by Pierre L. Triozzi, M.D. and Vernon C. Stevens, Ph.D. of The Ohio State University
Comprehensive Cancer Center, Columbus Ohio.
In summary, Drs. Triozzi and Stevens,
who have been examining the application of AVI's therapeutic vaccine Avicine(tm)
in cancer, conclude that "hCG is expressed by a variety of very common cancers,
and that several lines of evidence suggest that it may be an appropriate target for
cancer vaccines." The authors report that "synthetic peptide vaccines offer
a safe, stable, and cost-effective alternative to many preparations currently being
evaluated." They further report that hCG "may play a role in cell transformation
as well as angiogenic, metastatic, and immune escape phenomena that are central to
cancer progression." With respect to Avicine's ability to neutralize hCG biological
activity, Drs. Triozzi and Stevens note that "tolerance to this oncofetal antigen
can be broken and that both humoral and cellular responses have been generated in
clinical trials conducted to date."
Furthermore, Drs. Triozzi and Stevens
report that the transcription of hCG genes appears to be a common feature of malignant
cells. They also observed that the production of hCG may also play a role in cancer
progression by modifying tumor angiogenesis and metastasis and may provide tumors
with a mechanism by which they can evade immune effectors. Additionally, the anti-hCG
antibody induced with Avicine can "potentially mediate tumor elimination by
modulating the cellular biology mediated by hCG."
Denis R. Burger, Ph.D.,
President and Chief Executive Officer of AVI BioPharma, commented, "The extensive
data presented by Drs. Triozzi and Stevens validate our belief that hCG is an excellent
cancer vaccine target. We are confident that our lead anti-hCG vaccine agent, Avicine,
can generate highly specific hCG antibody responses with essentially no toxicity
to patients. As a result, we look forward to continuing down our clinical trial path
for Avicine in colorectal, pancreatic and prostate cancer over the next six months.
These studies in advanced cancer patients are expected to provide further evidence
of Avicine's ability to effect patient outcome by neutralizing the negative biological
activity of tumor-associated hCG."
Avicine is AVI BioPharma's lead product
candidate. As previously reported, Avicine elicits a highly specific immune response
to human chorionic gonadotropin (hCG), a hormonal cancer-associated oncofetal growth
factor. Detailed analysis of the Company's recently completed Avicine Phase II clinical
study in 77 patients with metastatic colorectal cancer provided evidence of survival
benefits comparable to Camptosar(R) (Lilly) chemotherapy and 5 Fluorouracil (5-FU).
Among all patients responding to Avicine immunotherapy, median survival was 42 weeks
compared to only 17 weeks in patients that did not respond immunologically. This
compares favorably to median survival of similar patients treated with Camptosar
and 5-FU (39 and 28 weeks respectively). When responding patients were evaluated
further, median survival increased to 46 weeks in patients randomized to the Avicine
low dose treatment arm.
"AVI BIOPHARMA INC. Reports Encouraging
Clinical Data From Multi-Center Phase II Study of Avicine in Advanced Colorectal
Cancer" PORTLAND, Ore.--(BW HealthWire)--Dec. 10, 1998
Patients Responding
to Avicine Demonstrate Increased Survival
AVI BIOPHARMA INC. today released
clinical data from a multi-center Phase II clinical trial of Avicine(tm), a therapeutic
cancer vaccine, in advanced colorectal cancer. The data reflects a two-year clinical
trial at 11 cancer centers throughout the United States in which two doses of Avicine
were compared in 77 patients with measurable metastatic colorectal cancer. The patients
were randomized to two treatment arms and evaluated to assess immunogenicity, safety
and efficacy of the vaccine. Overall, patient data demonstrates a measurable immune
response to human chorionic gonadotropin (hCG), increased survival in immune responders,
and from a safety standpoint, essentially no toxicity.
Colorectal cancer is
the third most frequent cancer type in the U.S. with approximately 131,000 diagnoses
and 55,000 deaths in 1997. Approximately one in 17 Americans will develop colorectal
cancer in their lifetime. Patients with advanced disease and 5-fluorouracil (5-FU)
treatment failures are currently treated with Camptosar(R) (Pharmacia & Upjohn,
Inc. (NYSE: PNU)) or an additional regimen of 5-FU. In this clinical setting, supporting
therapy results in a median survival of approximately 28 weeks, 5-FU results in a
median survival of approximately 37 weeks and Camptosar approximately 39 weeks.
Detailed
analysis of the clinical data revealed that approximately two-thirds of the patients
responded to the vaccine by producing antibodies to hCG, while the remaining one-third
were too ill or otherwise unable to mount an immune response. Importantly, overall
median survival in the group of patients responding to the vaccination was 42 weeks,
compared with a median survival of 17 weeks in patients that did not produce specific
antibodies. When the responding patients were evaluated further, and data segmented
into high- and low-dose treatment arms, low-dose immunotherapy resulted in a median
survival of 46 weeks, while the high-dose treatment group demonstrated a 39 week
median survival.
Patrick L. Iversen, Ph.D., AVI's Vice President of Research
and Development, commented, "It is important to note that in order to have effective
vaccine therapy, patients must be able to respond immunologically over 4-8 weeks,
the period it takes to mount an immune response. Patients unable to sustain an immune
response cannot hope to benefit from any cancer vaccine therapy. In this regard,
patients who received all doses of the vaccine over a 16-week evaluation period demonstrated
median survival of 58 weeks with low-dose immunotherapy and 44 weeks with the high-dose
regimen. Considering the advanced stage of cancer in these study patients, these
are truly remarkable and noteworthy results."
Denis R. Burger, Ph.D.,
President and CEO of AVI BioPharma, stated, "Based on the data collected to
date in both colorectal and pancreatic cancer, we are encouraged that Avicine has
demonstrated efficacy and safety, and may provide patients with an essentially non-toxic
therapy. The extensive Phase II data in advanced colorectal cancer validate our belief
that hCG is an excellent cancer vaccine target. As a result, we look forward to initiating
a multi-center Phase III licensing trial in 300 patients, which is expected to provide
further evidence of Avicine's ability to effect patient outcome by both anti-tumor
effector mechanisms and neutralizing the biological activity of tumor-associated
hCG."
AVI is also planning a Phase II study comparing patients with pancreatic
cancer treated with Avicine to patients treated with the combination of Avicine plus
gemcitabine (Gemzar(R)) produced by Eli Lilly & Co.; and a Phase II study treating
pancreatic cancer patients with Avicine in combination with a drug in Phase III clinical
trials developed by SuperGen, Inc. (Nasdaq NM: SUPG) called RFS-2000, an improved
topoisomerase-I inhibitor.
Avicine, a therapeutic cancer vaccine, is AVI BioPharma's
lead product candidate. Avicine elicits a highly specific immune response to the
human hormone and growth factor hCG, a cancer-associated oncofetal protein. Avicine
is essentially a non-toxic immunotherapy and has been evaluated in five clinical
trials. To date, more than 125 cancer patients have been treated. Early studies have
provided evidence of objective tumor responses and apparent survival benefits in
patients who have failed conventional therapy.
"Abgenix and AVI BioPharma Sign
License Agreementto Develop Human Antibody to Treat Cancer"
FREMONT,
Calif. and PORTLAND, Ore., Jan. 7 /PRNewswire/ -- Abgenix, Inc. and AVI BioPharma,
Inc. today announced that they have signed a research license and option agreement
to develop fully human antibodies to human chorionic gonadotropin (hCG). Under the
terms of the agreement, AVI will utilize the Abgenix XenoMouse(TM) technology to
generate product candidates for the treatment of cancer. AVI will be responsible
for product development, manufacturing and commercialization of any products developed
through the use of this technology. As part of the agreement, Abgenix has received
certain payments and could receive milestone payments based on product development
progress plus royalties on future product sales.
"We are very pleased
to be working with AVI BioPharma, our eighth corporate collaborator involving XenoMouse(TM)
technology, " stated R. Scott Greer, president and chief executive officer of
Abgenix. "AVI's clinical evaluation of hCG indicates that it may be a target
with significant potential as a cancer treatment."
Denis R. Burger, Ph.D.,
president and chief executive officer of AVI BioPharma, stated, "We look forward
to applying Abgenix's human antibody technology to our hCG development program. To
date, we are very encouraged by the results generated from our Phase II clinical
trials of Avicine(TM), our therapeutic cancer vaccine, in colorectal and pancreatic
cancer. These studies indicated that hCG may be an excellent cancer target, evidenced
by increased survival in immune responders. Although Avicine was highly effective
in two thirds of our colorectal patient study, patients unable to generate an immune
response did not benefit from this essentially non-toxic therapy. Using the Abgenix
XenoMouse(TM) technology, we plan to generate fully human antibodies to hCG for potential
use with the patient population that could not previously respond to any form of
immunotherapy. AVI's goal will be to use our hCG technology to treat all cancer patients,
including those with weakened immune systems."
Avicine is AVI
BioPharma's lead product candidate. As previously reported, Avicine elicits a
highly specific immune response to the human hormone and growth factor hCG, a
cancer-associated oncofetal protein. Avicine is essentially non-toxic
immunotherapy, which has been evaluated in five clinical trials. To date, more
than 125 cancer patients have been treated. Detailed analysis of the clinical
data gathered from Phase II colorectal studies revealed that approximately
two-thirds of the patients responded to the vaccine by producing antibodies to
hCG, while the remaining one-third were too ill or otherwise unable to mount an
immune response. Importantly, overall median survival in the group of patients
responding to the vaccination was 42 weeks, compared with a median survival of
17 weeks in patients that did not produce specific antibodies. When the
responding patients were evaluated further, low-dose Avicine treatment resulted
in a median survival of 46 weeks.
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