Biomarkers in Cancer Therapeutics
Objectives
·
Assess
the use of imaging modalities as correlates to physiologic markers
·
Evaluate
various approaches used to identify cellular markers of disease state,
progression of disease, and therapeutic competence (efficacy)
·
Determine
research needs for the advancement of marker identification useful in the
identification of early cancer detection and cancer therapeutic drug
targets
·
Identify
other technological approaches that will provide opportunities for
developing more and better biomarkers to measure therapeutic efficacy
·
Examine
the roles of industry, academia, and government in the development of
toxicity biomarkers
·
Determine
the current barriers impeding the development of biomarkers for cancer
therapeutics
Agenda
Moderators:
Albert F. LoBuglio, M.D., University of Alabama, Birmingham
James
M. Pluda, M.D., National Cancer Institute
S.
Percy Ivy, M.D., National Cancer Institute
Introduction
and Overview
Albert
F. LoBuglio, M.D.
Biomarkers
and the Impact on Drug Development
Biomarker Analysis in Human Carcinomas Subsequent to Epidermal Growth
Factor-Receptor Blockade Therapy Alone and in Combination With Cytotoxic
Agents
Robert
Radinsky, Ph.D., University of Texas M.D. Anderson Cancer Center
Biochemical Endpoints in Mechanism-Based Clinical Cancer Trials
James
K.V. Willson, M.D., University Hospitals of Cleveland and Case Western
Reserve University
Practical Issues in Current Drug Development: The Gross Philadelphia Chromosome as a Chronic Myelogenous
Leukemia Surrogate Endpoint; Progression-Free Survival as an Endpoint for
Tumoristatic Therapies
Robert
J. Spiegel, M.D., Schering-Plough Research Institute
HER2 Testing: Use of a
Biomarker To Select Therapy
Susan
D. Hellmann, M.D., M.P.H., Genentech, Inc.
Biomarker
Application in the Assessment of Cellular Mechanisms
Biomarkers and Angiogenesis—A Tabula Rasa
Thomas
Boehm, Ph.D., Children’s Hospital and Harvard Medical School
Prognostic Markers
Donald
Berry, Ph.D., Duke University
Biomarkers in Cancer Therapeutics (continued)
Technology
Interface With Pathophysiology
Radiolabeled Probes as a Tool for the Assessment of Receptor Expression
or Vascularity
Albert
F. LoBuglio, M.D.
Assessing the Effects of Antiangiogenic Therapy on Tumor Vasculature and
Metabolism Using Functional Imaging
Steven
K. Libutti, M.D., National Cancer Institute
Open
Discussion
Summary
James
M. Pluda, M.D.
Albert
F. LoBuglio, M.D.
S.
Percy Ivy, M.D.
Biomarker
Analysis in Human Carcinomas Subsequent to Epidermal Growth
Factor‑Receptor Blockade Therapy Alone and in Combination With
Cytotoxic
Agents
C.J.
Bruns, M.D.; P. Perrotte, M.D.; T. Matsumoto, M.D., Ph.D.; C.P.N. Dinney,
M.D.; and Robert Radinsky, Ph.D.
The
molecular mechanisms specific regulate the metastasis of tumor cells to
specific organs are diverse and both tumor and organ specific.
Data will be presented that demonstrate that the organ
microenvironment can influence the pattern of gene expression and the
biologic phenotype of metastatic tumor cells, including regulation of
cellular survival, angiogenesis, and growth at the organ‑specific
metastatic site. Insight into
the molecular mechanisms regulating this process as well as a better
understanding of the interaction between the metastatic cell and the
organ‑specific microenvironment provides a foundation for the design
of new therapeutic approaches. The
purpose of this study was to determine whether epidermal growth factor
receptor (EGF‑R) signaling regulates, in part, human bladder and
pancreatric carcinoma cell proliferation, invasion, or angiogenesis.
EGF‑R overexpression correlates with bladder (TCC) and
pancreatic carcinoma (PC) progression.
We evaluated whether EGF‑R blockade by use of (1) dominant
negative mutant EGF‑Rs, (2) EGF‑R‑specific tyrosine
kinase inhibitors, or (3) neutralizing anti‑EGF‑R antisera
(C225) has therapeutic benefits against high‑grade TCC and PC
growing orthopically in nude mice. In
vitro treatment of each cell type with EGF‑R blockade therapies
resulted in inhibition of EGF‑R‑specific phosphorylation as
measured by Western blotting and maximal 50 percent cytostasis.
A decrease was observed in expression of the angiogenic factors
vascular endothelial growth factor, IL‑8, and bFGF and the matrix
metalloproteinase 9 protease by the treated cells at both mRNA and protein
levels in a dose‑dependent manner (p<0.005).
In contrast, cell cycle‑related proteins such as p16, p21,
and CDK2 were not downregulated, although the cyclin‑dependent
kinase inhibitor p27 was elevated after treatment. Systemic therapy of established TCC and PC tumors with EGF‑R
blockade therapies alone or in combination with Taxol or gencitabine,
respectively, resulted in growth inhibition, tumor regression, and
abrogation of metastasis (p<0.0005).
Therapy conferred a significant survival advantage to the treated
mice (p=0.0001). The
expression of proliferating cell nuclear antigen, Rb, MMP9, VEGF,
IL‑8, and bFGF (protein and mRNA) levels was significantly reduced
in treated versus control tumors (p=0.001), whereas p27 levels were
induced to high levels. The
inhibition of the angiogenic peptides resulted in the subsequent
involution of the tumor neovascularization as determined by microvessel
density (p<0.005), contributing in part to an increased tumor cell
apoptotic index. These
experiments indicate that therapeutic strategies targeting EGF‑R
signaling have a significant antitumor effect, mediated in part by the
inhibition of cellular proliferation, invasion, and angiogenesis that
leads to apoptosis and tumor regression.
Ongoing studies are analyzing the identical biomarkers in patient
specimens subsequent to treatment with EGF‑R blockade therapies in
combination with cytotoxic drugs. Collectively,
these data support the hypothesis that the microenvironment of different
organs can influence the biological behavior of tumor cells during the
metastatic process and provide a therapeutic basis for interfering with
metastasis by downregulation of receptor number or function.
Biochemical
Endpoints in Mechanism‑Based Clinical Cancer Trials
James
K.V. Willson, M.D.
Our
group has conducted a series of mechanism‑based phase I clinical
cancer trials in which one endpoint of the trial was the modulation of a
molecular target. A procedure
for sequential computerized tomography‑guided biopsies of solid
tumors was developed to investigate the modulation of a biochemical target
in tumor tissues. In one
phase I trial, we used this approach to determine the dose and schedule of
a novel modulator of DNA alkyltransferase activity in tumor tissues.
In this trial, 28 patients completed sequential tumor biopsies
which proved informative for biochemical studies of alkyltransferase.
The drug level required to deplete the enzyme in the tumors was
tenfold higher than the drug area under the curve required to deplete
alkyltransferase activity in peripheral blood mononuclear cells. This experience demonstrates the feasibility of using
molecular endpoints in the development of cancer therapeutics. This
experience also demonstrates the limitation of studying a surrogate tissue
and the importance of investigating biochemical endpoints in the relevant
target tissue.
Key
References
Spiro
TP, Willson JKV, Haaga J, Hoppel CL, Liu L, Majka S, Gerson SL. O6‑benzylguanine
DNA alkyltransferase directed DNA repair. Proc Am Soc Clin Oncol
1996;15:178(A366).
Willson
JKV, Haaga JR, Trey JE, Stellato TA, Gordon NH, Gerson SL. Modulation of O6alkylguanine
alkyltransferase directed DNA repair in metastatic colon cancers. J Clin
Oncol 1995;13:2301‑2308.
Practical
Issues in Current Drug Development: The
Gross Philadelphia Chromosome as a Chronic Myelogenous Leukemia Surrogate
Endpoint; Progression‑Free Survival as an Endpoint for Tumoristatic
Therapies
Robert
J. Spiegel, M.D.
The
question to be addressed is, Are there now instances where outcomes short
of survival should be accepted as appropriate surrogates for new therapies
in the treatment of cancer? In
particular, Does the new genetic understanding of the basis of certain
malignant transformations allow demonstrations of effect on tumor genetics
to serve as adequate surrogates of new therapeutic's efficacy? In chronic myelogenous leukemia, the gross Philadelphia
chromosome (Ph1) aberration has been recognized for decades as a
pathognemonic marker of this disease.
With the introduction of interferon and bone marrow
transplantation, for the first time some patients were demonstrated to
lose detectable Ph1 following treatment.
A number of studies have now confirmed that those patients who lose
Ph1 can expect durable long‑term responses.
The question arises, Can the demonstration of loss of Ph1 and
normalization of hematologic values for some X period of time be
considered a suitable surrogate of treatment efficacy and preclude the
necessity of following cohorts of hundreds of patients over 3 to 5 years
to demonstrate survival benefit? This
model raises interesting questions for other therapies in the future,
which may be able to eliminate specific genetic defects that are easily
tracked. A larger and related
question involves the recent introduction into the clinic of new therapies
that are expected to produce tumoristatic rather than tumoricidal effects.
Some current approaches to gene therapy such as replacement of
tumor suppressor genes (p53) or reversal of oncogenic gene stimuli (farnesyl
protein transferase inhibitors in RAS‑positive tumors) may produce
successful control of tumor growth but without bystander effect and
without dramatic conventional tumor responses.
These approaches to cancer therapy may well produce control of
existent tumor but not elimination. Demonstration
of clinical benefit in these circumstances may take hundreds of patients
followed for many years, and this produces serious challenges to the
normal development process where early readout is necessary to optimize
drug formulations or determine a positive decision to invest further
resources. A discussion of
specific therapeutic approaches and specific disease settings will be
made.
Key
References
Anon.
Interferon alfa‑2a as compared with conventional chemotherapy for
the treatment of chronic myeloid leukemia. The Italian Cooperative Study
Group on Chronic Myeloid Leukemia. N Engl J Med 1994;114:820‑825.
Guilhot
F, Chastang C, Michallet M, Guerci A, Harousseau JL, Maloisel F,
Bouabdallah R, Guyotat D, Cheron N, Nicolini F, Abgrall JF, Tanzer J.
Interferon alpha‑2b combined with cytarabine versus interferon alone
in chronic myelogenous leukemia. French Chronic Myeloid Leukemia Study
Groups. N Engl J Med 1997;337:223‑229.
Kantarjian
HM, Smith TL, O'Brien S, Beran M, Pierce S, Talpaz M. Prolonged survival
in chronic myelogenous leukemia after cytogenetic response to
interferon‑alpha therapy. The Leukemia Service. Ann Intern Med
1995;122:254‑261.
Ohnishi
K, Ohno R, Tomonaga M, Kamada N, Onozawa K, Kuramoto A, Dohy H, Mizoguchi
H, Miyawaki S, Tsubaki K, et al. A randomized trial comparing
interferon-alpha with busulfan for newly diagnosed chronic myelogenous
leukemia in chronic phase. Blood 1995;86:906‑916.
Talpaz
M, Kantarjian H, Kurzrock R, Trujillo JM, Gutterman JU.
Interferon‑alpha produces sustained cytogenetic responses in chronic
myelogenous leukemia. Philadelphia chromosome‑positive patients. Ann
Intern Med 1991;114:532‑538.
HER2
Testing: Use of a Biomarker
to Select Therapy
Susan
D. Hellmann, M.D., M.P.H.
The
use of biomarkers to select therapy has been a frequent topic for
theoretical discussion. Herceptin,
a recently approved humanized monoclonal antibody, is the first drug whose
use is specifically based on the presence of a biomarker, the HER2/neu
oncogene. The challenges
associated with the practical implications of using a biomarker to select
therapy will be discussed.
Biomarkers
and Angiogenesis—A Tabula Rasa
Thomas
Boehm, Ph.D.
The
field of angiogenesis research and particularly the application of the
antiangiogenesis concept as a potential way to treat cancer were pioneered
by Judah Folkman during the past 30 years.
During the past 5 years, several potent or less potent molecules
have been found to be capable of controlling certain aspects of
angiogenesis and thereby of blocking tumor growth.
Nevertheless, only a handful publications can be found on biomarker
and angiogenesis. In
addition, these publications describe molecules secreted from tumor cells
to stimulate endothelial cells (bFGF and VEGF).
In other words, these proteins are not real markers for
angiogenesis but for the presence of tumor cells.
It is now generally accepted that tumor cells need to establish an
adequate capillary network to expand. This
means that endothelial cells will undergo phenotypical changes, because
they have to migrate, proliferate, degrade, and remodel the matrix to
accomplish the task of forming a functional unit supplying the tumor cells
with oxygen and nutrients. If
these phenotypical changes can be measured and quantified, we could detect
cancer earlier or follow antiangiogenic therapy.
Before this can be accomplished, these endothelial
cell‑specific molecules lost or overexpressed during tumor growth
must be identified. A possible approach to isolate real endothelial cell marker
will be presented.
Key
References
Dirix
LY, Vermeulen PB, Pawinski A, Prove A, Benoy I, De Pooter C, Martin M, Van
Oosterom AT. Elevated levels of the angiogenic cytokines basic fibroblast
growth factor and vascular endothelial growth factor in sera of patients.
Br J Cancer 1997;76(2):238‑243.
Jinno
K, Tanimizu M, Hyodo I, Nishikawa Y, Hosokawa Y, Doi T, Endo H, Yamashita
T, Okada Y. Circulating vascular endothelial growth factor (VEGF) is a
possible tumor marker for metastasis in human hepatocellular carcinoma. J
Gastroenterol 1998;33(3):376‑382.
Kumar
H, Heer K, Lee PW, Duthie GS, MacDonald AW, Greenman J, Kerin MJ, Monson
JR. Preoperative serum vascular endothelial growth factor can predict
stage in colorectal cancer. Clin Cancer Res 1998;4(5):1279‑1285.
Landriscina
M, Cassano A, Ratto C, Longo R, Ippoliti M, Palazzotti B, Crucitti F,
Barone C. Quantitative analysis of basic fibroblast growth factor and
vascular endothelial growth factor in human colorectal cancer. Br J Cancer
1998;78(6):765‑770.
Moses
MA, Wiederschain D, Loughlin KR, Zurakowski D, Lamb CC, Freeman MR.
Increased incidence of matrix metalloproteinases in urine of cancer
patients. Cancer Res 1998;58(7):1395‑1399.
Nguyen
M, Watanabe H, Budson AE, Richie JP, Hayes DF, Folkman J. Elevated levels
of an angiogenic peptide, basic fibroblast growth factor, in the urine of
patients with a wide spectrum of cancer. J Natl Cancer Inst
1994;86(5):356‑361.
Prognostic
Markers
Donald
Berry, Ph.D.
Prognostic
markers are of little clinical interest unless they have therapeutic
implications. Despite some attitudes to the contrary, it may not be
appropriate to use the most intensive and most toxic therapies with
patients having the poorest prognosis.
But assessing interactions between therapy and biomarkers is
difficult and requires very large numbers of patients.
Such assessment is made even more difficult because the typical
experiment involves assessing numerous markers.
A result is that the false‑positive rate increases, giving
rise to biomarkers that are flashes in the pan.
These and related problems in the case of HER‑2/neu and p53
and their possible interaction with doxorubicin in node‑positive
breast cancer will be discussed as well as the general notion of using
surrogate markers in clinical research from the Bayesian perspective.
Radiolabeled
Probes as a Tool for the Assessment of Receptor Expression
or
Vascularity
Albert
F. LoBuglio, M.D.
A
recent phase I clinical trial utilizing a humanized anti‑Vitronectin
receptor provided an opportunity for our group to initiate attempts at
measuring antibody binding or blockade of this angiogenesis‑dependent
endothelial cell receptor. We
proposed that it may bind available Vitronectin receptors and that
administration of radiolabeled tracer doses might be used to image tumor
vascular bed and when administered postinfusion of a therapeutic dose,
might demonstrate blockade of the receptor.
This initial attempt was only partially successful and suggested
that the antibody’s binding affinity was too low, and particularly, its
“off‑rate” was too rapid. Evidence for this hypothesis was then presented by Viti and
colleagues who showed that single‑chain antibodies directed to an
alternative intravascular target were only able to image the tumor
vascular bed if their off‑rate was very slow.
Such high‑affinity and low off‑rate versions of the
anti‑Vitronectin receptor antibody have been described.
The generalization of this concept (i.e., use of a probe carrying
an isotope or other imaging agent as a means of delineating the tumor
vascular bed) might well be applicable to magnetic resonance imaging and
positron emission tomography scanning as a means of estimating
“volume” or “extent” of vascular bed per volume of tumor.
Key
References
Brooks
PC, Clark RA, Cheresh DA. Requirement of vascular integrin alpha v beta 3
for angiogenesis. Science 1994;264(5158):569‑571.
Viti
F, Tarli L, Giovannoni L, Zardi L, Neri D. Increased binding affinity and
valence of recombinant antibody fragments lead to improved targeting of
tumoral angiogenesis. Cancer Res 1999;59(2):347‑352.
Assessing
the Effects of Antiangiogenic Therapy on Tumor Vasculature and Metabolism
Using Functional Imaging
Steven
K. Libutti, M.D.
As
new anticancer agents are developed that target the tumor neovasculature,
novel approaches to measuring responses are needed.
Functional imaging has been suggested as a means of detecting
changes in tumor blood flow and metabolism.
Several challenges confront the development of these new
technolgies. We must identify
noninvasive methods to quantify changes in tumor vasculature, and we must
validate these methods as a means of quantifying the effects of
antivascular agents. We must
also be able to control for variability of repeated measures.
Finally, we must be able to coregister images with traditional
scans to follow the responses of particular lesions over time. We have identified several advanced imaging modalities that
we believe have the potential to address these challenges:
positron emission tomography (PET) utilizing radiolabeled glucose (18FDG),
radiolabeled carbon monoxide (11CO), radiolabled water (H2O15),
and dynamic magnetic resonance imaging (MRI).
PET‑FDG relies on the fact that malignant lesions have
elevated glycolysis, and therefore there is increased uptake of [18‑F]
fluorodeoxyglucose. Conversion
of 18FDG to 18FDG‑6‑phosphate
occurs, which traps the radioisotope in neoplastic tissues.
Our hypothesis is that changes in tumor vascularity in response to
agents may alter glucose metabolism and therefore change the amount of
uptake of 18FDG. PET‑CO is designed to assist in the quantification of
tumor blood volume. 11CO
is administered by inhalation, binds tightly to red blood cells, and has a
short half‑life (20 minutes). Red
blood cell volume can be quantified as can changes in blood volume over
time. PET‑H2O allows for the measurement of tumor
blood flow. H2O15
is delivered intravenously and is rapidly cleared (half‑life
< 5 minutes). Short
scanning times can be used, and flow in tumor vessels can be standardized
to major vessels and to arterial blood samples.
The technique has been validated in myocardial and cerebral blood
flow studies. Dynamic MRI
relies on the rapid (more than 1 minute) administration of a
gadolinium‑based contrast agent.
Ultrafast analysis of signal intensity and patterns of contrast
uptake within tumors can correlate with microvessel density. Pharmacokinetic modeling of gadolinium clearance—as well as
measurements such as the rate of enhancement, time to peak enhancement,
clearance rate, and area under the curve—can be performed.
Recent advances in MRI utilizing gradient‑recalled echo and
inhaled carbogen may enhance these measurements.
Our current clinical trial is designed to evaluate these various
imaging modalities in patients currently being treated with antiangiogenic
agents (anti‑VEGF, thalidomide, isolated hepatic perfusion).
Pretreatment imaging with CT, PET, and dynamic MRI is followed by
interval imaging while on therapy. Correlation
with tumor biopsy is performed when available.