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Diagnostic Approaches to Maximize Therapeutic Effect 191
methodology that will facilitate the monitoring of patients with malignant diseases
to be treated with T cell–based immunotherapy in order to determine the
clinical significance and future directions.
It is becoming increasingly advantageous to screen patients for expression
of TAA for development of an antigen profile for the tumor in order to select the
immunotherapeutic product and/or regimen based on the profile. Besides being
advantageous for patient-positive selection for clinical use, these diagnostic
methods are also advantageous to determine, diagnose, or confirm diagnosis of
cancer and monitoring or predicting disease progression in a cancer patient. The
goal is to have an assay in place that is relatively inexpensive to practice and that
provides the ability to assay large numbers of samples in a limited amount of
time. Tumor tissue to assay can be obtained as bulk tissue through surgery or in
cellular form from blood, bone marrow, cellular aspirates, and peritoneal,
bronchial, or plural aspirates, among others.
Staining of formalin-fixed tissue sections provides reliable information
about the expression of HLA1 in lesions from various types of cancer. The
reactivity of anti-HLA1 with various molecular-based technologies and b2M
and TAA mAb with formalin-fixed tissues provides the opportunity to perform
retrospective studies, utilizing collections of pathological lesions from patients
with detailed information about the clinical course of the disease (30–32).
Immunohistochemical analysis of different types of cancer with an apparent
different involvement of immunological events in their pathogenesis and in their
clinical course generates clinically useful information (32). IHC is broadly
applicable, but western hybridization, RIA, and flow cytometry can also be used.
Reagents such as T cell lines and hybridomas, and more preferably, antibodies
specific for the peptide-MHC complex and TCR tetramers that detect presentation
of particular T-cell epitopes from target antigens can also be used (33).
TCR tetramer–based assays allow simultaneous confirmation of both MHC and
target antigen or target epitope expression and are inherently type specific.
TCR-Like Immunoglobulin (TCRL) as a Potential Diagnostic Tool in
Pretreatment Screening
MKC’s cancer vaccine is aimed at eliciting an effective CTL response that is
the ultimate effector to eradicate tumors. CD8 þ T cells recognize tumor cells in
an antigen-specific, MHC-restricted manner through the interaction between
TCR and a peptide fragment derived from tumor antigens bound to MHC1
molecule. Thus, antigen expression is the prerequisite for patients eligible to
receive the vaccine. Despite IHC, RT-PCR, PCR, and in-situ hybridization
being the common techniques to address antigen expression, none of them can
verify that tumor antigens are processed and presented on MHC1 molecules by
tumor cells.