Clinical trials of genetic therapy with antisense DNA and DNA vectors

448 Pages·1998·385.711 MB·English

by  Wickstrom, Eric

Clinical Trials
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MARCEL DEKKER, INC. NEw YoRK • BASEL • HoNG KoNG
DEKK ER
Library of Congress Cataloging-in-Publication Data
Clinical trials of genetic therapy with antisense DNA and DNA
vectors/e dited by Eric Wickstrom.
p. em.
Includes bibliographical references and index.
ISBN 0-8247-0085-6 (alk. paper)
1. Gene therapy-Testing. 2. Antisense DNA-Therapeutic use-
Testing. 3. Genetic vectors-Therapeutic use-Testing. 4. Clinical trials.
I. Wickstrom, Eric.
[DNLM: 1. Gene Therapy. 2. DNA, Antisense. 3. Genetic Vectors.
4. Clinical Trials. QZ 50 C641 1998]
RB155.5.C5728 1998
616'.042-dc21
DNLM/DLC
for Library of Congress 98-13317
CIP
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Foreword: Genetic Therapy in the
21st Century
0. Michael Colvin
Duke University Medical Center, Durham, North Carolina
The elucidation of the nature of the genetic code by Watson and
Crick in 1952 presaged that we will ultimately be able to describe the
determinants of the normal structure and functions of our bodies. The
rapid increase in our ability to identify genes and sequence them is
bringing that goal steadily closer to reality. A logical extension of this
ability will be the capability to ascertain the genetic abnormalities asso-
ciated with specific diseases, including cancer, and to treat these diseases
by returning the altered segments of the genetic code to normal, or in
some other way utilizing genetic knowledge and techniques for treatment.
At this time a number of such initiatives are in preclinical development
and several have entered the clinical trial stage. Examples of these
preclinical and clinical efforts are described in this volume.
Efforts in genetic therapy have taken two general approaches. The
first is the introduction into the patient of a vector that can insert into the
genetic code a sequence that will restore a normal function or alter an
abnormal function. Probably the most readily achieved example of this
approach will be to introduce a gene for a single missing enzyme. A more
difficult task will be to reverse a malignant state in all the cells of a tumor.
More immediately realized antitumor efforts will likely be the genetic
enhancement of the function of immune cells to recognize and eradicate a
tumor; the induction of a portion of the cells in a tumor to secrete an
antisense molecule, a ribozyme, or other lethal entity to attack those cells
and neighboring malignant cells; or introduction of an enzyme into tumor
iii
iv Foreword
cells which will activate a potent antitumor agent selectively in the region
of the tumor.
A second general approach to using the genetic code to treat disease
is to deliver to the affected cells antisense molecules that enter abnormal
cells and by sequence recognition selectively inhibit a pathologic process
in these cells. This approach has been limited by problems of selectivity
for specific genetic sequences, inadequate avidity of binding to the target
sequence, and inadequate delivery of the molecules into tissues and into
cells.
The delivery of agents to tumor cells has traditionally been more
readily accomplished with leukemias than with solid tumors, and for this
reason we are most likely to initially see beneficial clinical effects with
antisense molecules in leukemias. The problems with delivery also
suggest that the initial significant successes will be in local applications of
antisense technology, such as local administration to stenotic vasculature,
the purging of tumor cells from bone marrow and stem cells, local
injection into accessible tumors, and intraocular administration, as de-
scribed in these chapters.
However, it seems very likely that more successful delivery of both
vectors and antisense molecules will be achieved. It is probable that at
least limited evidence of effectiveness will be forthcoming from the
studies discussed here and from other studies underway. Nevertheless, as
with any difficult challenge, the full realization of the potential of this
therapeutic approach will depend on our ability to select the appropriate
targets, to improve the delivery of the agents to the critical sites, and to
optimize the effector functions of the agents. In this respect it is critical in
the clinical experiments to understand why the efforts do not work when
they don't, and how they could work better when they do.
This volume clearly demonstrates that genetic therapy is underway,
and that the efforts described are soundly based in rationale and
feasibility. However, we must remember that successful genetic therapy
represents a formidable technical challenge whose promise well justifies
our efforts to bring this type of treatment to fruition. This promise and
our increasing understanding of the mechanisms of conversion of the
genetic code into function indicate that gene-based therapy will become a
mainstay of disease control in the 21st century.
It is appropriate to remember that the first antitumor agents were
introduced into clinical therapy a half century ago. In retrospect, most of
the subsequent challenges and successes of cancer therapy were
predictable from the initial clinical experiments. I believe the same will be
true for the genetic therapy of cancer and other diseases.
Preface: From Theory to Practice in
Thirty Years
Eric Wickstrom
Tbomas jefferson University, Philadelphia, Pennsylvania
This collection of clinical and preclinical reports on genetic therapy
is designed to inform clinical and biomedical investigators in all disease
areas of gene-based interventions which appear to be plausible at this
time, by presenting a few examples of the wide variety of current studies
in this field. Since this editor's first volume on this subject (Wickstrom,
1991), the whole field of genetic therapy, by antisense DNA and by DNA
vectors, has advanced dramatically. Subsequent advances of genetic
therapy in cell culture (Crooke and Lebleu, 1993) and in animals
(Agrawal, 1996) have been described in later volumes.
A number of laboratories have published results of successful
human clinical trials. A larger series of papers on clinical trials of genetic
therapy will be published over the next year. Thus, thirty years after the
first suggestion of nucleic acid therapy against naturally occurring gene
sequences (Belikova, et al., 1967), and the first demonstration of antisense
activity in cell culture (Zamecnik and Stephenson, 1978), successes have
been achieved in clinical trials.
Traditionally, chemotherapy agents for cancer or viral diseases have
been designed to inhibit the enzymes necessary for cell growth or
production of new viruses. Chemotherapeutics have strong side effects,
extending to fatal toxicity. The diseased cells often become resistant to
existing drugs, so new approaches are needed for effective disease
management.
v
vi Preface
Cloning and sequencing of pathogenic genes over the last two
decades have made possible a direct genetic approach to the treatment of
disease, using nucleic acid therapeutics or vectors. The ability to tum off
individual disease-causing genes, or correct them, or replace them at will
in a patient's cells provides a powerful tool for therapeutic intervention in
genetic diseases. Gene-specific nucleic acid therapy has gone from theory
to practical possibility in a very short time.
These new DNA and RNA agents are intended to stop the growth of
cancerous cells, the production of HIV from infected cells, the production
of faulty proteins, or the pathogenic absence of necessary proteins, or to
make abnormal cells more easily recognized by the immune system. Aside
from traumatic events that require surgical repair, one may now say that
all diseases represent examples of genetic dysfunction.
In the Foreword, Dr. 0. Michael Colvin describes the scope of the
present volume, which extends from nucleic acid therapeutics acting as
drugs to tum off pathogenic genes to biological vectors carrying
antisense, ribozyme, corrected, replacement, or immunostimulatory genes.
Questions of preparation, delivery, toxicity, mechanism, and specificity
are addressed.
Following this Preface, a brief history of genetic therapy is provided
by Dr. James Hawkins, followed by a section on synthesis, preparation,
and production of synthetic oligonucleotides and biological vectors.
Applications to treat gene deficiencies, leukemia and lymphoma, solid
tumors, human immunodeficiency virus (HIV), cytomegalovirus (CMV),
and coronary restenosis are described in subsequent sections.
In the preparation section, the perspective and expectations of the
Food and Drug Administration towards synthetic oligonucleotides are
discussed by Drs. Ahn and DeGeorge, while the practical considerations
of meeting FDA requirements for large-scale cGMP production are
described by Dr. Gonzalez and his colleagues. Similarly, the perspective
and expectations of the Food and Drug Administration towards biological
vectors are discussed by Dr. Epstein, while practical considerations of
large-scale cGLP production are described by Drs. Davis and Baker.
Focusing on treatment of adenosine deaminase deficiency, Drs.
Gordon and Anderson recount their clinical experiences with vector
administration. For hematological malignancies, several approaches to
treatment of leukemia and lymphoma are presented. Drs. Gewirtz and
Sokol describe their experiences treating patients with chronic
myelogenous leukemia with antisense DNA against c-myb oncogene. In
the case of acute myelogenous leukemia, Dr. Iversen discusses the
pharmacokinetics and toxicity of an oligonucleotide against the tumor
suppressor gene p53. Next, a clinical trial of anti-bc/2 DNA oligomers to
Preface vii
treat follicular lymphoma is reported by Dr. Cotter and his colleagues. In
the area of bone marrow transplantation therapy, Drs. Abonour and
Cometta describe improvements in ex vivo retroviral transfection of stem
cells with marker genes and drug resistance genes.
Therapy of solid tumors is considered next, beginning with applic-
ation by Dr. Alavi and her colleagues of an adenoviral vector capable of
transforming glioma! cells to ganciclovir, in patients with brain cancer.
Preclinical and phase I clinical trials of a retroviral vector encoding an
antisense RNA against c-fos oncogene in breast, prostate, and ovarian
cancer cells are then reported by Dr. Obermiller and her colleagues. In an
attempt to boost immune cell responses to tumor cells, Drs. Stopeck and
Hersh discuss their clinical experiences using cytolytic T cells expressing
an allogeneic MHC class I antigen. Dr. Roth then presents the results of
treating lung cancer with retroviral p53 tumor suppressor gene replace-
ment, while bladder cancer is the focus of a preclinical study of
adenoviral delivery of ribozyme genes against H-ras oncogene, described
by Dr. Small and his colleagues. To elevate immune cell responses in
patients with melanoma, Drs. Lattime and his colleagues then report on
the efficacy of vaccinia virus for insertion of granulocyte-macrophage
colony-stimulating factor gene insertion for immunotherapy using vaccinia
virus vectors.
In the HIV section, Dr. Agrawal describes administration to patients
of antisense DNA against HIV gag gene, with little or no toxicity detected.
For opportunistic CMV infection of the retinas of AIDS patients, Dr.
Crooke reports that intravitreal treatment with an oligonucleotide comple-
mentary to a CMV immediate early gene clearly reduced the severity of
infection, with modest side effects.
Finally, two different approaches to prevention of arterial restenosis
following coronary bypass or balloon angioplasty are presented. An oli-
gonucleotide complementary to c-myc mRNA, the first antisense DNA
applied to an oncogene (Wickstrom, 1991), successfully inhibited
remodeling and regrowth of vascular smooth muscle cells in the hearts of
both pigs and human patients, as described by Dr. Zalewski and his
colleagues. In preclinical trials, Dr. Mann and his colleagues report that
encapsulation of antisense DNA, double-stranded decoy DNA, or plasmids
with hemagglutinating virus of Japan permitted excellent cellular uptake
and potency of gene therapy agents against a panel of proliferative genes
expressed in animal models of restenosis.
The CMV therapeutic discussed by Dr. Crooke is currently in a
Phase III trial, and may plausibly be approved for prescription and sale
this year, two years earlier than this editor's previous prediction
(Wickstrom, 1991). Great efforts must be applied to careful and thorough