California Cancer Research Program
Completed Projects
The following Principal
Investigators have completed their research as funded by CRP. Where applicable,
publications resulting from CRP funding are also included.
CYCLE I FINAL LAY
ABSTRACTS
Robert C. Brasch, M.D.: MRI Grading of Ovarian Cancer Microvessels
Richard J. Cote, M.D.: Detection and Mechanism of Occult Metastasis in
Prostate Carcinoma
Stavros G. Demos, Ph.D.: Endoscopic Subsurface Optical Imaging for
Cancer Detection
Lee Goodglick, Ph.D.: Pathway for Prostate Cancer Resistance to an
Anticancer Agent
Lawrence
W. Jones, M.D.: Rhodamine-123: Innovative Treatment for
Prostate
Cancer
Young S. Kim, M.D.: Chemopreventive Effect of Balsalazide on Colorectal
Polyps
Shen Pang, Ph.D.: A Prostate-Specific Lentiviral Vector for Gene
Therapy
Donna M. Peehl, Ph.D.: Vitamin D and Prostate Cancer: Risk, Prevention
and Therapy
Eila C. Skinner, M.D.: Effect of Selenium on Prostate Tissue of High Risk
Men
Rowan
T. Chlebowski, M.D., Ph.D.: Androgen Ablation and Co-Morbid
Disease in Prostate Cancer
Faye A. Eggerding, M.D., Ph.D.: Molecular Markers of Prostate Cancer
Risk
Romaine E. Saxton, Ph.D.: Laser and Hypericin Phototherapy for
Squamous Cell Carcinoma
Atsuko Shibata, M.D., Ph.D., M.P.H.: Genetic Markers and Prostate
Cancer Prognosis
Michael Albert Thomas, Ph.D.: Diffusion-Weighted MRI and MR
Spectroscopy of Prostate Tumors
Virginia Urquidi, Ph.D., M.Sc.: Stage-Specific Gene Expression in Ovarian
Cancer Progression
Henry F. VanBrocklin, Ph.D.: Choline-Based Imaging Agents for
Non-Invasive Tumor Detection
Timothy D. Solberg, Ph.D.: A Novel Approach to Intensity Modulated
Radiotherapy
Paul O. Zamora, Ph.D.: Absorbable Brachytherapy Devices for Cancer
Therapy
University of California,
San Francisco
Investigator-Initiated
Award, $711,284.00 / 36 mos.
(Ovarian Cancer)
The formation of new blood
vessels, termed angiogenesis, is essential to the exponential growth and
metastatic spread of cancer. The
currently evolving understanding of angiogenesis, its promoters and its
inhibitors, has already led to a proliferation of new drugs to reduce tumor
morbidity and mortality. Knowledge
of the angiogenic status of a given tumor can define prognosis and can be used
to select between therapeutic options.
New techniques using magnetic resonance imaging (MRI) and innovative
diagnostic drugs, contrast media, under development by our group can define the
vascular characteristics of tumors.
These MRI-defined vascular characteristics are a direct reflection of
angiogenic status. MRI vascular
characterizations can be used not only to better understand the biology of tumors
as a whole, but also to specifically characterize an individual tumor for
prognostic and treatment purposes.
Thus, this research program addresses two CPR priorities, tumor
detection with individual risk assessment and innovative treatment with anti-angiogenesis
drugs.
A multidisciplinary team
including those with expertise in diagnostic imaging, pharmacokinetics,
gynecologic oncology, physics, and chemistry has addressed the problem. Tumor angiogenic status has special
significance for ovarian cancer, the focus of this program. The majority of ovarian cancer patients
present with advanced disease with ascites fluid in the abdomen, ascites being
a major cause of patient suffering.
Tumor production of ascites has been directly linked to angiogenesis,
specifically to vascular endothelial growth factor (VEGF) a known mitogen and
potent enhancer of vessel permeability.
A new MRI technique, tested in this program, has been shown in
experimental studies to measure the permeability of tumor microvessels with
respect to macromolecular contrast agents. In the current research proposal, a refined technique for
MRI microvascular characterization has been evaluated with success for its
potential to characterize ovarian cancer, predict the accumulation of ascites,
and monitor the effect of anti-angiogenesis treatments designed to inhibit
cancer growth and ascites production.
Results from these studies serve to better our understanding of
angiogenesis and its relation to ascites production and to enhance the transfer
of new techniques in the fields of
MRI, contrast media, and angiogenesis to clinical practice and patient
management.
1. Gossmann A, Helbich TH, Mesiano S,
Shames DM, Wendland MF, Roberts TPL, Ferrara N, Jaffe RB, Brasch RC: Magnetic
resonance imaging in ovarian cancer demonstrating altered microvascular
permeability following inhibition of vascular endothelial growth factor. American Journal of Obstetrics and
Gynecology, 2000; 183(4): 956-963.
2. Daldrup-Link HE, Shames DM, Wendland
MF, Muehler A, Gossmann A, Rosenau W, Brasch RC: Comparison of Gadomer-17 and
Gadopentetate for differentiation of benign from malignant breast tumors by MR
imaging. Academic Radiology, 2000;
7(11): 934-944.
3. Brasch RC, Turetschek, K: MRI characterization of tumors and
grading angiogenesis using macromolecular contrast media: status report. European Journal of Radiology, 2000;
34:148-155.
4. Turetschek K, Huber S, Floyd E, Helbich
TH, Roberts TPL, Shames DM, Tarlo KS, Wendland MF, Brasch RC: MR imaging characterization
of microvessels in experimental breast tumors by using a particulate contrast
agent with histopathologic correlation.
Radiology, 2001; 218:562-569.
5.
Turetschek, K, Floyd E, Shames DM, Roberts TPL, Preda A, Novikov V,
Corot C, Carter WO, Brasch RC: Assessment of a rapid clearance blood pool MR
contrast medium (P792) for assays of microvascular characteristics in
experimental breast tumors with correlations to histopathology. Magnetic Resonance in Medicine, 2001;
45:880-886.
6. Turetschek K, Floyd
E, Helbich TH, Roberts TPL, Shames DM, Wendland MF, Carter WO, Brasch RC: MRI
assessment of microvascular characteristics in experimental breast tumors using
a new blood pool contrast agent (MS-325) with correlations to histopathology. Journal of Magnetic Resonance Imaging,
2001; 14(3): 237-242.
Rowan T. Chlebowski, M.D., Ph.D.
University of California,
Los Angeles
Pilot and Feasibility
Study Award, $179,201.00 / 24 mos.
(Prostate Cancer)
Prostate cancer is a leading
cause of cancer and the second leading cause of cancer death. Despite these facts, approximately two
thirds of men diagnosed with prostate cancer die of other causes. Currently, the most effective therapy
against disseminated prostate cancer is androgen ablation either by surgery or
medication. However, androgen
ablation may be considered a doubled edged sword since reports have suggested
that androgen ablation may influence the course of a number of chronic diseases
adversely.
To evaluate this important
issue, we performed the first comprehensive cross-sectional evaluation of the
effects of androgen ablation on risk factors and intermediate markers of
chronic disease conditions. A total
of 58 prostate cancer patients with controlled disease (PSA < 10) were
studied including 31 in a non-androgen ablation group and 28 in an androgen
ablation group. Androgen ablation
status was confirmed using serum testosterone levels. Only men with low testosterone levels were included in the
androgen ablation group. After
informed consent all participants had a physical examination, careful blood
pressure measurements, anthropometric measurements, body composition analysis,
complete blood counts, basic chemistry panels, fasting glucose, fasting
insulin, C-peptide, growth hormone, bone turnover measures and lipid
panels. In addition EKGÕs and
neuropsychological testing were performed. The men also underwent muscle strength testing and
ultrafast-CT scan to determine coronary calcification as a marker of heart
disease risk. At this time all
analyses are complete.
Despite contrary suggestions
in the literature, lipid profiles including cholesterol, low density
lipoprotein and high density lipoprotein were closely comparable in the
androgen ablation and the non-androgen ablation groups. Thus, androgen ablation had no adverse
effect on lipid profile. There
were somewhat fewer abnormal electrocardiograms seen in the androgen ablation
group as well. The picture
regarding the influence of androgen ablation on cardiac disease risk factors
was mixed since the average blood pressures were higher in the androgen
ablation group and the calcium coronary calcium scores were also higher in the
androgen ablation group suggestive of increased cardiovascular disease
risk. With respect to hormonal
profiles linked potentially to diabetes, fasting insulin and glucose were
comparable in the androgen ablation and non-androgen ablation groups. The
androgen ablation group was somewhat glucose intolerant with higher fasting
two-hour glucose levels and lower two-hour insulin levels seen compared to the
men without androgen ablation.
With respect to body composition, men in the androgen ablation group had
a greater amount of body fat and had a greater percentage of body fat than the
prostate cancer patients without androgen ablation. Bone mineral density was also not surprisingly reduced in
men with androgen ablation.
In summary, our study of the non-prostate cancer effects of
androgen ablation resulted in a mixed picture but one that provides some
reassurance. With respect to
cardiac disease some adverse indicators were associated with androgen ablation
but other parameters were not adversely influenced. Glucose metabolism abnormalities were seen in the androgen
ablation group only following the oral glucose tolerance test suggesting some
glucose intolerance and increased diabetes risk. The body composition differences seen were not unexpected as
the potential for osteoporosis in prostate cancer patients with androgen
ablation is well known. Our future
efforts will concentrate on the potential role of exercise in mitigating some
of the potentially adverse effects of androgen ablation so that the risk benefit
ratio of this important therapeutic intervention can be more fully
realized.
University of Southern
California
Investigator-Initiated
Award, $690,842.00 / 36 mos.
(Prostate Cancer)
Cancer of the prostate often
appears to be confined to that gland and therefore should be curable by
complete removal of the gland or irradiation. The reason that prostate cancer recurs after such treatment
is that small populations of tumor cells that cannot be detected by routine
analysis have escaped from the gland.
We term these Ôoccult metastasesÕ and they may be found in the blood,
bone marrow and lymph nodes. There
are two distinct methods used to detect occult metastases. One is by applying special stains that
specifically bind to proteins in the cancer cells that are normally not found
in blood, bone marrow or lymph nodes.
The second method is to amplify prostate specific gene products in the
blood and bone marrow by polymerase chain reaction. The goals of this project are to determine the number of
patients who have these cells present in their blood, bone marrow or lymph
nodes and to ascertain what implications this has in terms of disease
progression.
We examined the blood from 90
patients using special stains and found tumor cells in 6.7% of them. Sixty-nine of these patients had their
blood tested using the molecular method and 13% were found to be positive. We also looked at the bone marrow of 93
patients by special stains and found 18.3% to be positive for occult
metastases. Eighty-one of these
patients were tested using molecular methods and 19.8% were found to be
positive. While occult metastases
were detected in both the blood and bone marrow and most of the patients with
positive blood samples also had positive bone marrow, the rate of detection was
higher in the bone marrow. We also
analyzed the lymph nodes from 66 of these patients. All had histologic negative lymph nodes by routine
analysis. We found that 8% (5/66)
were positive. We have also compared
the lymph node results with the bone marrow results as determined by
immunohistochemistry. We found
that only 20% (1/5) of the lymph node occult metastases positive cases have
occult metastatic cells in the bone marrow. This is an entirely new finding that indicates that occult
metastases in the different compartments represent different populations of
patients. Follow-up studies will
be able to determine which compartment is more important in terms of disease
progression.
In addition to our work
examining case matched lymph nodes along with the blood and bone marrow of
patients with prostate cancer, we have been examining the lymph nodes from a
cohort of men with long term follow-up data. We have a total of 141 patient samples in this arm of the
study. All of the lymph nodes
removed at surgery were evaluated, and in all cases the original pathology
analysis did not reveal detectable tumor cells in any of the lymph nodes. A total of 2820 lymph nodes (an average
of 7.2 per patient) were examined.
We were able to identify tumor cells in 18/141 (12.8%) patients who were
previously believed to be free of lymphatic disease. Follow-up of these patients for approximately 10 years
showed that the estimated survival and the duration of time to disease relapse
were significantly lower in patients with tumor cells detected in their lymph
nodes.
Therefore, the identification
of early prostate cancer spread in the blood, bone marrow and lymph nodes may
be a useful tool to help define therapeutic options for these patients,
including the need for surgery, radiation therapy and chemotherapy. This could clearly be of great benefit
to patients, and may have important economic impact.
Lawrence Livermore
National Laboratory
Investigator-Initiated
Award, $1,089,794.00 / 36 mos.
(Prostate/Colorectal
Cancer)
This research project
represents an effort to develop novel instrumentation to be employed in the
continuous effort to fight cancer. More specifically, this project involves the
development of endoscopic subsurface imaging technology that can be used as a
minimally invasive early cancer detection/screening and diagnostic tool. The
images obtained will be able to provide information of different tissue
structures on the surface and below the surface at different depth zones. The
utilization of this technology can be incorporated into different types of
existing endoscopes allowing for subsurface imaging inside the human body. This
imaging technology provides fast image acquisition, involves least expensive
equipment and can be utilized in a doctorÕs office or in the field.
The physical basis of this
subsurface imaging method for cancer detection originates in the differences in
the interaction of light with cancer and normal tissue arising from their
differences in the cellular level (size of the cells, density, cell makeup and
biochemical composition). Two main techniques are explored based on imaging
using light scattering and autofluorescence under laser excitation. The images
attained using the light scattering method represent differences in absorption
by blood or other chemical substance and scattering due to the presence of
different types of tissue at different depths. Photon discrimination methods
using polarization and light scattering spectral filtering followed by image
processing allow for effective removal of the image information of the outer
layers of the tissue and enhancement of the contrast and image quality of
subsurface tissue structures. Biochemical fluorophores activated by laser
excitation are used in the second method for tissue imaging and
characterization. As part of this research effort, we have undertaken the task
of building an endoscopic system for subsurface imaging inside the human body
and test it in a clinically relevant environment. This imaging system
incorporated existing technology that has been developed for medical endoscopes
with the appropriate modifications to accommodate the proposed subsurface
imaging technology. This "endoscope" type system will be able to
perform the measurements utilizing low cost off-the-self components, will be
user friendly requiring no particular specialization nor exposure of the
operator to any harmful radiation and will be minimally invasive for the
patient. The possible applications will involve cancer detection at early
stages in the skin, bladder, lung, bronchus, uterus, cervix, GI track, prostate
and kidney. In addition, this imaging technology may find application in
providing minimally invasive monitoring of the tumorÕs response to various
stages of treatments and in assisting during surgery by providing information
on the depth of penetration of the tumor.
Human and animal tissue
samples are studied in order to optimize and test the optical imaging
modality's ability to address a number of clinical situations. This is achieved
using prototype instrumentation that has been build at LLNL and used at the UC
Davis Medical Center. The key parameters such as illumination wavelength and
source, imaging depth and resolution, ability to distinguish between normal
tissue and maligned or benign tumors in various body parts are the focus of our
effort. Our experimental results have been very encouraging suggesting that
both imaging and cancer detection approaches we are investigating may prove
fruitful. The application of this technology for the detection of cancer in
bladder, colon, prostate and kidney is our initial objective.
1. Demos SG, Staggs M, Radousky HB, Alfano RR,
ÒInstrumentation for subsurface imaging in a clinical environmentÓ, SPIE, 3917, 62-66, 2000.
2.
Demos SG, Staggs
M, Radousky HB. ÒEndoscopic subsurface imaging in tissuesÓ, J. A. Conchello, C. J. Cogswell, T.
Wilson, Eds., SPIE, 4261, 122, 2001
3.
Demos SG, Staggs
M, Radousky HB, Gandour-Edwards deVere White RR. ÒCancer detection using NIR
elastic light scattering and tissue fluorescence imagingÓ, CLEO '01 Technical
Digest, (Optical Society of
America, Washington, D. C.), pp. 361.
4.
Demos
SG, Staggs M, and Radousky HB. Endoscopic method for large-depth optical
imaging of interior body organs. Electronics Letters. 2002. 38: p. 155-7.
5.
Demos
SG, Staggs M, Radousky HB, Gandour-Edwards R, Ramsamooj R, and deVere White R.
eds. Tissue imaging for cancer detection using NIR autofluorescence. Optical
Biopsy IV. ed. Alfano RR. Vol. 4613. 2002. SPIE.
6.
Demos
SG, Gandour-Edwards R, Ramsamooj R, White R. Near-infrared autofluorescence imaging for detection
of cancer. J
Biomed Opt. 2004 May-Jun;9(3):587-92
Faye A. Eggerding, M.D., Ph.D.
Huntington Medical
Research Institutes
Pilot and Feasibility
Study Award, $143,846.00 / 24 mos.
(Prostate Cancer)
Prostate cancer is the most
common malignancy in American men and as such it poses major public health
challenges. Androgens play a
pivital role in the evolution of prostate cancer and hormonal therapies
designed to inhibit the action of androgens remain the mainstay of treatment
for retarding the growth of advanced prostate cancer. Sadly, almost all patients eventually become resistant to
hormonal threrapy and their cancers then
progress rapidly. New ways
to identify individuals at risk for developing this disease and effective
strategies for identifying those early cancers that will progress to aggressive
disease are critically needed.
Our research addresses these
issues and is focused on characterization of genetic markers specific for
prostate cancer initiation and progression and on identification of common
genetic variants associated with increased susceptibility to prostate
cancer. Through our research
sponsored by the California Cancer Research Program we have developed methods
based on gene amplification technology to study the structure of the androgen
receptor gene in early and advanced cancers and to identify polymorphic
variants of the androgen receptor gene that may predispose to development of
cancer. We have developed
protocols to enable analysis of
the androgen receptor gene from buccal cells scraped from inside the cheek and collected
on swabs; this simple assay will greatly facilitate analysis of large
populations for androgen receptor variants. Because androgens play a key role in prostate development
and tumor formation, mutations and variants of this gene as well as other genes
in the androgen metabolism pathway may contribute significantly to prostate
cancer risk and to prostate cancer aggressiveness.
A prostate cancer consists of
cancer cells, blood vessels, connective tissue cells and immune cells. We have developed a method using
a stereo-microscope and micro-manipulator to dissect and separate the tumor
cells from connective tissue cells (stromal cells) present in the tumor for
individual genetic analyses. In a
single assay we are able to moniter the expression of thousands of genes. With these methods we hope to identify
reproducible patterns of gene expression and to identify a few key genes as
markers for development of a simple molecular test capable of telling whether a
lesion has the potential to develop into an aggressive tumor.
These studies are of great
importance as they may lead to identification of new genes whose expression is
altered during prostate cancer initiation and progression. Once identified, these novel
prostate-specific genes can be used as reagents for development of diagnostic
tests for prostate cancer early detection and as therapeutic targets for cancer
treatment. Identification of
common gene variants associated with predisposition to prostate cancer will
lead to screening tests for prostate cancer susceptibility, thus enabling
disease prevention.
University of California,
Los Angeles
New Investigator Award,
$302,610.00 / 36 mos.
(Prostate Cancer)
Extensive research and
clinical effort has focused on developing novel anti-cancer approaches with the
goal of inducing death to malignant cells while sparing normal, healthy tissue.
Achieving such specificity has been difficult since many targeted pathways are
common in both malignant and normal cells. An additional complication is the
exquisite ability of tumor cells to adapt and evolve and thus effectively
become resistant to specific therapies.
Our laboratory has been
studying a chemotherapeutic agent called 9-nitrocamptothecin (or 9-NC). In
experimental model systems, 9-NC has the properties of killing tumor cells but
not normal cells. The mechanism for this selective toxicity is not completely
understood. However, similar to other therapies, some tumor cells can
ultimately become resistance to 9-NC. As outlined previously, the goal of this
grant is to determine the mechanism of resistance of prostate cancer cells to
9-NC. During this funding period, we made significant progress on this issue.
Specifically, we utilized a number of state-of-the-art, high throughput
approaches (e.g., subtractive hybridization, cDNA microarray analysis, etc.) to
identify the molecular basis of this resistance.
We found that changes in the
expression of a number of genes that normally govern the life and death of a
cell, appeared to be the culprits. In particular, we focused on one
particularly important gene, called 14-3-3. 14-3-3 is an interesting protein in
that it regulates the activity of other proteins through binding and
sequestering these proteins in locations where they remain inactive. We
originally found that 14-3-3 levels were decreased in cells that were resistant
to 9-NC killing. Moreover, we could replicate this finding by artificially
introducing 14-3-3 into tumor cells that were normally killed by 14-3-3; this
manipulation made these cells resistant. We have further addressed the
questions of what is 14-3-3 regulating, and similarly, what is regulating
14-3-3. With regard to the former, we have found that 14-3-3 directly or
indirectly regulates the expression level of a number of proteins that dictates
when a cell lives or dies. With regard to the regulation of 14-3-3, we are
focusing on a protein called RKIP, which appears to directly or indirectly
control 14-3-3.
In conclusion, funding
through the California Cancer Research Program has been instrumental in
allowing us to make a number of significant discoveries on the mechanism by
which tumor cells can progress and become resistant to therapies. These
findings represent a universal theme not just a peculiarity of 9-NC treatment.
Our subsequent research efforts will be focused on both a more detailed
understanding of this mechanism at the cellular and molecular level, as well as
a translation of these results for use as potential prognostic indicators and/or
therapeutic targets.
1. Chatterjee D, Goldman M, Braastad CD, Darnowski J,
Wyche JH, Pantazis P, and Goodglick L. Reduction of
9-nitrocamptothecin-triggered apoptosis in DU-145 human prostate cancer cells
by ectopic expression of 14-3-3zeta. Int J Oncol. 2004. 25(2): p. 503-9.
2. Wadehra M, Braun J, and Goodglick L. One-step
RT-PCR for screening microdissected tissue samples. Biotechniques. 2002. 32(2):
p. 242, 244, 246, 248.
3. Wadehra M, Iyer R, Goodglick L, and Braun J. The
tetraspan protein epithelial membrane protein-2 interacts with beta1 integrins
and regulates adhesion. J Biol Chem. 2002. 277(43): p. 41094-100.
Huntington Memorial
Hospital
Investigator-Initiated
Award, $441,918.00 / 36 mos.
(Prostate Cancer)
Prostate cancer is the
leading cause of cancer-related death among men, accounting for more than
32,000 deaths annually in the United States. In California alone, 3,700 men die from prostate cancer each
year. The development of a
treatment which can be safely and effectively administered to men with
otherwise incurable prostate cancer has potentially life-saving benefits for
thousands of men in California and beyond each year.
The object of this Phase 1
study was to assess the toxicity of an innovative treatment for prostate
cancer: Rhodamine-123.
Rhodamine-123 is an
industrial dye traditionally used in photography labs and in research labs to
study malignant cells. Over the
last decade, studies have shown that Rhodamine-123 may also be effective in
attacking cancer cells, including prostate, the most common cancer diagnosed
among men. The purpose of the
proposed study was to determine the highest safe dose and the safety of
multiple doses of Rhodamine-123 as chemotherapy for patients with otherwise
incurable prostate cancer
The study involved 29
volunteer patients with metastatic hormone-refractory prostate cancer - cancer
that is spreading and for which no other course of treatment has been successful. The mechanism of action of
Rhodamine-123 is to interfere with the energy system of the cell by disrupting
mitochondrial enzymes. The study
has been divided into two parts.
In the first part of this study volunteers received a single infusion of
Rhodamine-123. The first group of
volunteers received Rhodamine-123 at a dose determined to be safe in
pre-clinical studies. Subsequent groups received increased dosages until a
toxic level of the agent was determined.
A safe dosage of Rhodamine-123 was then established as one level below
the toxic level. In the second part of this study, the frequency of infusions
was increased from one infusion to six infusions (once per month), using the
safe dosage of Rhodamine-123 as identified in the first part of the study.
Both parts of this Phase 1
study have been completed. They
have shown that a safe dosage of Rhodamine-123 can be given at monthly
intervals for a total of six infusions.
Northern California
Institute for Research and Education, Inc.
Investigator-Initiated
Award, $970,960.00 / 36 mos.
(Colorectal Cancer)
Colorectal cancer is the
third most commonly diagnosed cancer in both men and women and the second
leading cause of death due to cancer in the U.S. It is widely accepted that effective preventive approaches
offer us the best hope of reducing its incidence and mortality. Most colorectal cancers are believed to
arise in pre-existing adenomatous polyps (adenomas). Although most adenomatous polyps grow slowly and never
develop into cancer, certain factors are associated with malignant
transformation, such as the number and size of the polyps. The currently accepted method of
screening for colorectal cancer in symptom free people age 50 or older includes
sigmoidoscopy or colonoscopy and removing polyps at an early stage.
Some non-steroidal
anti-inflammatory drugs (NSAIDs) including aspirin reduce the risk for either
colorectal adenomas or cancers in both humans and animals. However, NSAIDs also cause serious
complications such as gastrointestinal bleeding, intestinal strictures and
kidney toxicity, particularly at large dosages. Recently a new aspirin-like drug called balsalazide has been
developed. It consists of an aspirin-like
molecule linked to an inert carrier molecule that is poorly absorbed in the
small intestine, unlike free aspirin.
When balsalazide enters the colon, a free aspirin-like compound is
released from the inert carrier molecule in high concentrations and exerts its
effects directly on colonic mucosa and polyps. Since very little free aspirin-like compound gets into the
circulation it has few side effects.
In fact, recent clinical trial studies to test the anti-inflammatory
effect of balsalazide (another effect of NSAIDs) in patients with ulcerative
colitis indicate that beneficial therapeutic effects of balsalazide were not
accompanied by serious side effects.
Further, in two recent animal studies in our laboratories, balsalazide
inhibited intestinal tumor formation.
The major goal of our study
is to determine whether this new and safe drug, balsalazide, can reduce the
size of adenomatous polyps over a 6 month period in persons with small polyps
(0.3 - 0.9 cm) found on routine screening sigmoidoscopic and colonoscopic
examination. The secondary goal is
to examine the effect of balsalazide on markers of cell growth and programmed
cell death in normal colonic mucosa.
If balsalazide changes the level of expression of these markers they can
then serve as intermediate end points in future chemoprevention trials,
shortening the trial period considerably.
To date, 220 patients
consented to enter the trial and underwent initial endoscopy and 76 of these
were found to have the small polyps required for eligibility. Sixty of these patients have completed
the trial. Since we are
using a blinded, placebo-controlled trial design we will not be able to
determine the effectiveness of balsalazide in reducing polyp size or its
effects on marker levels until after the trial is completed (unblinded) when we
will know which patients recieved balsalazide and which recieved placebo. We are currently seeking additional
funding to enroll a sufficient number of patients to achieve statistical
significance in this study.
University of California,
Los Angeles
Investigator-Initiated
Award, $620,328.00 / 36 mos.
(Prostate Cancer)
The prostate-specific antigen
(PSA) promoter is known to be highly tissue-specific. Although its tissue specificity has been confirmed, its efficiency
of gene transcription is significantly lower compared to known non-specific
viral promoters. These lower
levels of promoter activity therefore pose a problem when developing an
efficacious gene vector for prostate cancer gene therapy. Thus, selecting an appropriate
therapeutic gene and vector system to carry the gene driven by the PSA promoter
(PSAP) is important. In this
study, we used an HIV‑1-based lentiviral vector carrying either the
enhanced green fluorescent protein (EGFP) reporter or the diphtheria toxin A (DTA)
gene to infect prostate cancer cells.
Using cell cultures, we
demonstrated that the PSA promoter in a lentiviral vector drives genes in prostate
cells with satisfactory efficacy and specificity. The tissue-specific expression of the DTA protein efficiently
eradicates LNCaP prostate cells in culture. We also infected prostate cancer cells and control cells carried
by nude mice with the EGFP lentiviral vector. Significant numbers of EGFP-positive LNCaP cells were
detected in all the mice bearing these tumors, but no EGFP-positive control
cells were detected in any other mouse tissue.
We then performed tests using
specific mice, the mice with defective immune system to grow human prostate
cancer. When our DTA gene therapy vector has been injected into the prostate
tumors in these mice, significant tumor shrinks have been demonstrated in
approximately 80% of the animals.
Our tests using both cell
cultures and animal models suggest that our prostate tissue-specific lentiviral
DTA vector has the potential for gene therapy of prostate cancer. The high levels
of expression in prostate cells, compared with the low levels of background
expression in other cells, provide a unique advantage for using our prostate
tissue-specific lentiviral vector for eradicate prostate cancer cells.
1.
Yu D, Chen D, Chiu C, Razmazma B, Chow Y-H, and Pang
S. Prostate-specific targeting using PSA promoter based lentiviral vectors. Cancer Gene Therapy. 2001, 8:628-635.
2.
Chow YH, Yu D, Zheng JY, An D-S, Xie Y, Poon B, Wei
OLC, Chiu C, Park NH, O. Yang, Chen ISY, and Pang S. gp120-independent
Infection of CD4- Epithelial Cells and CD4+ T-cells by HIV-1. J. AIDS, 30:1-8.
2002.
3.
Zheng, J-Y, Chen D, Chan J, Yu D, Ko E, Pang S.
Regression of prostate cancer xenografts by a lentiviral vector specifically
expressing diphtheria toxin A. Cancer Gene Therapy, 2003, Oct;10(10):764-70.
Stanford University
Investigator Initiated
Award, $1,426,528.00 / 36 mos.
(Prostate Cancer)
Prostate cancer is the most
commonly diagnosed cancer among men in the U.S. and is the second most common
cause of all cancer deaths in men.
Using cell culture systems and animal models of human prostate cancer,
we previously showed that vitamin D is an anti-proliferative and
differentiating agent on normal and malignant prostatic epithelial cells. In a pilot study to test therapeutic
activity of vitamin D, we found that the rate of growth of tumors which
recurred after radiation therapy or radical prostatectomy was slowed.
The studies that we completed
during our project are relevant to risk, prevention and therapy of prostate
cancer. With regard to risk, we
examined the relationship of genetic variants (polymorphisms) in the vitamin D
receptor (VDR) to risk of relapse following radical prostatectomy to surgically
treat prostate cancer.
Vitamin D must bind VDR in order to effect cellular growth or
differentiation. We found
that individuals with a particular variant of the VDR ( the "f" form)
have a greater chance of relapse than individuals with the "F"
form. This suggests that the
"f' form of VDR may be less functional than the "F' form, resulting
in less tumor-suppressive activity of vitamin D in cancer cells with this form
of VDR.
Our studies regarding the
enzyme, 1-hydroxylase, that synthesizes the active form of vitamin D are
relevant to prevention of prostate cancer. We found that normal prostate cells have high levels of
1-hydroxylase and convert the inactive precursor 25-vitamin D to the active,
growth-inhibitory 1,25-vitamin D.
Prostate cancer cells, however, have significantly less 1-hydroxylase
activity than normal cells. We
found that this was true even of cells from early stage cancer, suggesting that
loss of 1-hydroxylase activity may be a key element in cancer initiation. If 1-hydroxylase activity could be
restored, perhaps the tumor suppressor effects of locally synthesized
1,25-vitamin D would prevent the development of prostate cancer. Our studies so far suggest that normal
and cancer cells have equivalent levels of 1-hydroxylase RNA and protein, and that
the difference is in enzymatic activity. In future studies, we will determine if a critical co-factor
is absent in prostyate cancer cells.
Other studies that we
completed are relevant to treatment of prostate cancer. We developed a rationale for
combination therapy with ketoconazole and 1,25-vitamin D. Ketoconazole is commonly used to treat
androgen-independent prostate cancer.
However, ketoconazole blocks synthesize of 1,25-vitamin D, so patients
treated with ketoconazole may suffer the detrimental side effects of vitamin D
insufficiency. On the other hand,
ketoconazole also inhibits degradation of 1,25-vitamin D, so that administered
1,25-vitamin D would remain at high levels longer. Combination ketoconazole/21,25-vitamin D therapy therefore
should alleviate symptoms of vitamin D deficiency and perhaps enhance
anti-tumor activity of 1,25-vitamin D.
Our preclinical studies with prostate cancer cell cultures indeed showed
that ketoconazole enhanced growth suppressive activity of 1,25-vitamin D,
providing a basis for the development of clinical trials.
The final project that we
carried out this past year was to use cDNA microarray analysis to identify
genes regulated by vitamin D in normal and malignant prostate cancer
cells. Genes known to be
regulated by vitamin D from previous studies were found to be regulated,
validating this new technology.
Novel targets of vitamin D were also identified, providing the starting
point for future experiments to determine the molecular mechanisms of vitamin D
action in prostate cells. Differences
were found in the genetic response of normal and cancer-derived cells that may
relate to escape of cancer cells from inhibition by vitamin D.
In summary, our preclinical
studies show that prostate cancer cells have defects in both synthesis of and
response to vitamin D. Since
vitamin D is a tumor suppressor, these defects may be important in cancer
development.
1. Hsu J-Y, Feldman D, McNeal JE, Peehl DM. Reduced 1alpha-hydroxylase activity in
human prostate cancer cells correlates with decreased susceptibility to
25-hydroxyvitamin D3 – induced growth inhibition. Cancer Res. 2001;61:2852-2856.
2. Peehl DM, Seto E, Feldman D. Rationale for combination
ketoconazole/vitamin D treatment of prostate cancer. Urology 58 (Suppl. 2A): 123-126, 2001.
3. Peehl, D.M., Seto, E., Hsu, J-Y. and Feldman,
D. Preclinical activity of
ketoconazole in combination with calcitriol or the vitamin D analog EB 1089 on
prostate cancer cells. J Urol.
2002 Oct;168(4 Pt 1):1583-8.
4. Shibata A, Garcia MI, Cheng I, Stamey TA, McNeal
JE, Brooks JD, Henderson S, Yemoto CE, and Peehl DM. Polymorphisms in the
androgen receptor and type II 5 alpha-reductase genes and prostate cancer
prognosis. Prostate. 2002. 52(4): p. 269-78.
5.
Xu Y, Shibata A, McNeal JE,
Stamey TA, Feldman D, Peehl DM.Vitamin D receptor start codon polymorphism
(FokI) and prostate cancer progression. Cancer Epidemiol Biomarkers Prev. 2003
Jan;12(1):23-7.
University of California,
Los Angeles
Pilot and Feasibility
Study Award, $199,641.00 / 24 mos.
(Skin Cancer)
Over half of all human
cancers of the head and neck recur locally following conventional surgery,
radiation, or chemotherapy. Nearly all of these recurrent squamous cell tumors
of the mouth, nose, or throat lead to death within 3-5 years. Our recent
development of a minimally invasive nontoxic treatment that can be repeated for
gradual tumor ablation promises to become an effective adjuvant therapy in
these cases of recurrent cancer.
Hypericin (HP), a nontoxic
pigment isolated from St. John's Wort, is lethal to tumor cells in test tubes
after exposure to low level visible light. Patients with squamous or basal cell
carcinoma also have been successfully treated by topical administration of
hypericin and white light. Hypericin has been shown to be a tumor-specific dye
for fluorescent endoscopy of bladder carcinoma in situ. We have recently
reported that HP and laser fiberoptics can be combined for treatment of human
squamous carcinoma tumor transplants in nude mice (Laryngoscope. 110:1312-1316,
2000). We have now optimized this nontoxic dye and laser therapy for successful
treatment of human adenocarcinoma and squamous cell tumors. Digital imaging of
KTP532 laser induced dye fluorescence at various times after injection
(50ug/0.05ml), revealed HP spreading gradually from the intra-tumor injection
sites over several hours until reaching the tumor margins. HP was visible as
bright orange fluorescence throughout these tumors for 10-14 days, but was not
seen in adjacent normal tissue.
Tumor aspirates examined by
confocal laser microscopy 1 hour after HP injection had initial cell membrane
and mitochondrial fluorescence with dye migration into the tumor cell nucleus
by 24 hours. Hypericin was effective in treatment of tumors up to 500 mm3 using
several cycles of pulsed KTP laser light (532nm, 200ms pulse, 600mW, 100J, Tmax
= 43C) delivered into tumors via a flexible 600um bare fiber tip to induce
lethal photo-oxidation. Rigid squamous cell tumors became noticeably softer
several days after treatment with aspirates containing an increasing proportion
of nonviable cells seen by Trypan blue staining via microscopy.
The procedure was
well-tolerated and could be repeated 2-3 times per week without use of
anesthesia and no apparent discomfort. Recently, complete regressions were seen
in over half of cases (n=29) using this new protocol for gradual tumor ablation
over a course of 4 to 10 weeks.
Followup for the next 3-6 months revealed margin recurrence in several
instances with successful retreatment in all cases. We are continuing to follow
up these encouraging therapy responses and have begun testing other human
tumors transplanted to internal organs of mice to evaluate the usefulness of
this treatment method in types of cancer that metastasize.
Although experimental, this
preclinical data indicate that hypericin and laser phototherapy are an
effective tumor treatment with little host toxicity. This method may become a
useful adjuvant treatment in malignancies like squamous cell carcinoma that
recur locally after conventional therapy in about half of head and neck cancer
patients. Because this novel
approach combines traditional herbal medicine and laser electronics for the
first time as a successful
technique in gradual ablation of recurrent tumors, it appears likely we
will need to perform more
laboratory studies before approval is obtained for our university surgeons to
begin clinical tests.
1.
Chung
PS, Rhee CK, Kim KH, Paek W, Chung J, Paiva MB, Eshraghi AA, Castro DJ, Saxton
RE.Intratumoral
hypericin
and KTP laser therapy for transplanted squamous cell carcinoma. Laryngoscope. 2000
Aug;110(8):1312-6.
2.
Liu
CD, Kwan D, Saxton RE, and McFadden DW. Hypericin and photodynamic therapy
decreases human pancreatic cancer in vitro and in vivo. J Surg Res. 2000.
93(1): p. 137-43.
Atsuko Shibata, M.D., Ph.D., M.P.H.
Stanford University
Pilot and Feasibility
Study Award, $196,499.00 / 24 mos.
(Prostate Cancer)
Prostate cancer is the most
commonly diagnosed cancer (except for non-melanoma skin cancer) in U.S. men. A
remarkable increase in prostate cancer incidence rates in US men in late 1980's
and early 1990's, however, have been attributed partly to the increased use of
prostate-specific antigen (PSA) testing for screening prostate cancer in men
with no clinical symptoms. One of the challenges in prostate cancer research is
to identify markers that can distinguish tumors that would be fatal if left
untreated from less aggressive counterparts. We are investigating the clinical
significance of the DNA sequence variants in two genes that are associated with
the functional activity of male sex hormones in relation to prostate cancer
prognosis. Since the products of these two genes are among the determinants of
prostate cell growth and replication, their functional activities may be
related to the progression of prostate cancer. DNA sequence variants of these
genes, if they were associated with pathological characteristics of prostate
cancer and clinical outcome (failure to cure), might serve as markers for
predicting prognosis.
Our study includes 221 men
who were diagnosed with prostate cancer and underwent radical prostatectomy
between 1992 and 1996 at Stanford Medical Center. To date, we have identified
subjects who met our selection criteria, abstracted data on pathological
features of prostate cancer and serum PSA levels after surgery from existing
databases, performed molecular assays for DNA sequence variants of our interest,
and performed statistical analysis to address the study goals. Our data suggest
that none of these three DNA sequence variants of the genes involved in
androgen metabolism and function was a significant predictor of tumor pathology
indicating aggressiveness of tumor at the time of surgical treatment. In
contrast, men with certain DNA sequence variants in these genes seem more
likely to experience tumor recurrence after radical prostatectomy. However, our
findings are not consistent with results of some other studies that addressed
similar research questions. We need to carefully assess limitations and biases
of our study as well as other studies before drawing conclusions.
We also examined the
association of the same DNA sequence variants with risk of benign prostate
enlargement. We found that men with shorter versions of a DNA repeat sequence
in the androgen receptor gene had elevated risk of having large prostate after
adjustment for age. This finding suggests that variation in the androgen
receptor function due to the DNA sequence variation may influence benign
enlargement of the prostate.
This research project has
helped us better understand the involvement of androgen-related genes in
prostate cancer progression and risk of prostate enlargement. Strengths of this
study have included the use of unique resources at our institution (archive of
prostate glands that have been systematically evaluated by a pathologist and
follow-up data on serum PSA levels) and strong multidisciplinary collaboration
among epidemiologists, pathologists, molecular biologists, and clinicians with
expertise and sustained interests in prostate cancer research.
University of Southern
California
Investigator-Initiated
Award, $1,217,810.00 / 36 mos.
(Prostate Cancer)
Prostate cancer is the most
common cancer diagnosed in American men today, and is the second most common
cause of cancer death. Although
major strides have been made in early detection and treatment of localized
disease, many patients are still unable to be cured once diagnosed with the
disease, and treatment can significantly impact on quality of life. Primary prevention of the cancer holds
the best chance for reducing the death rate due to prostate cancer in this
country.
Selenium is a trace element
in our diet which has been shown to have some potential protective effects for
cancer in general, and specifically for prostate cancer. Although early data are promising, they
are not yet conclusive enough to recommend that all men take this supplement. We still do not know enough about how
selenium works or whether it will be helpful for men who are at particularly
high risk of developing prostate cancer.
At USC, we have developed a
model for studying potential cancer prevention agents in men at high risk of
developing prostate cancer. These
are men who have an elevated prostate specific antigen blood test (PSA), but
have had a prostate biopsy which is negative for cancer. With this model we studied the actual
prostate biopsy tissue before and after treatment with selenium supplementation
or a placebo for one year. We
looked for the effect of selenium on the growth rate of the normal prostate
cells, the development or disappearance of pre-cancerous lesions, and the
actual incidence of cancer at one year.
Of the 160 men enrolled, 133
have completed the protocol and have had a 12-month biopsy. Another two men are scheduled for their
12-month biopsy and pending. Of
these 135 men, 54.81% are Caucasian, (n = 74), 32.6% are Hispanic (n = 44),
6.67% are Asian (n = 9), and 5..93% are African-American (n = 8). We initially allowed for a 25% dropout
rate; we have achieved a 15.6% rate (25 of 160). An additional ten men (total of 145 men) have completed 12
months on study but have refused the 12-month biopsy, and are included in the
compliance and laboratory values analysis.
Medication compliance remains excellent. Of the 146 patients reaching 12 months on-study, 77% missed less than 5% of their pills, and 87% missed less than 10% of their pills. Of the 146 men reaching 12 months on study, one had begun taking a prohibited medication, Proscar. The mean serum selenium level of the remaining 145 men has increased from 122.86 ug/L to 134.71 ug/L. In this