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Cancer Vaccines and Immunotherapy

Cancer Vaccines and Immunotherapy

For the past 20 to 30 years, enormous resources have
been directed toward the development of effective cancer immunotherapies. The
interest in immunotherapeutic approaches comes from the potential specificity
imparted by the recognition of tumor-specific antigens combined with the
powerful cytolytic properties of cellular and humoral immune effector arms.
Earlier attempts to induce and/or expand tumor antigen-specific immune
responses in patients involved the systemic administration of cytokines such as
interleukin-2 (Proleukin), or immunization with vaccines prepared from whole
tumor cells or tumor cell lysates admixed with powerful immunologic adjuvants
(stimulators). Unfortunately, only limited efficacy was achieved.

Over the past 15 years, several developments stimulated further interest and
growth in the introduction of cancer vaccines to the clinic. They include the
rapid progress in understanding the basic features of antigen presentation and
immune recognition, thus providing a means for more effective immunization;
progress in molecular biology that permitted the identification of numerous
potential tumor-specific or tumor-associated antigens; the increased
availability of recombinant cytokines, proteins, peptides, and other components
necessary to generate a vaccine product; and the relative ease with which
foreign genes such as cytokines or tumor antigens could be expressed in viruses
and cells.

Despite substantial efforts in the field and progress in basic understanding,
critical aspects of the biology and immunology related to optimal induction of
antitumor immune responses, and even the basic parameters of an effective
antitumor immune response, remain unknown. No clear best approach to inducing
antitumor immune responses has emerged. For these reasons, many different cancer
vaccines involving many different potential antigens and antigen presentation
approaches are currently in clinical development.

The editors of Cancer Vaccines and Immunotherapy have assembled a collection
of concise, well-written chapters by several leading figures in the field that
highlight many of the major areas of research and the important development
issues for cancer vaccines. The initial chapter provides a useful overview of
the basic features of antigen presentation, immune recognition of antigen,
immune effector arms, the interaction of the host immune system with the tumor
during tumor growth, types of tumor antigens, the rationale for the selection of
certain tumor antigens and antigen-presentation approaches, and the mechanisms
of tumor escape. The chapters that follow address specific immunization
approaches (eg, poxviruses, anti-idiotypes, and dendritic cells), vaccine
approaches for specific diseases (B-cell tumors, colon cancer, cervical cancer,
Epstein-Barr virus-related cancers), and tumor antigen discovery (SEREX
[screening of cDNA expression libraries derived from human tumors with
autologous antibody] and CTL [cytotoxic T lymphocyte] epitopes).

The chapters generally contain a generous number of helpful illustrations and
tables, and are organized to include an introductory section (with basic
information on the relevant disease or the basic biology supporting the
approach) and conclusions (which encompass future directions). In the final two
chapters, the editors provide a useful overview of the major issues introduced
and some discussion to relate these issues to current findings and prospective
possibilities.

Because the chapters are concise yet cover a broad range of diverse topics,
the book will be most useful to oncologists and immunologists who have limited
familiarity with cancer vaccines and would like greater knowledge of current
issues and developments in the field. The book may also be useful for those
seeking more in-depth knowledge of a selected topic, such as poxvirus vectors or
vaccine approaches in cervical cancer.

However, because of its organization and selected coverage of topics, the
book is not comprehensive and should not be considered a sole source of
information on cancer vaccines. For example, the coverage of melanoma vaccines—which
represents a significant portion of the work in the field—is somewhat limited.
Most of the book is devoted to defined-antigen vaccines, with less attention
paid to whole tumor cell vaccines, tumor cell lysates, or tumor cell components
such as heat-shock proteins, and gene-modified tumor cells. Paradoxically, one
chapter is devoted to intravesical bacillus Calmette-Guérin (BCG) instillation
for bladder cancer, which is arguably not a cancer vaccine but more of a
nonspecific immunotherapy.

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