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M94B0778.TXT
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1994-11-11
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Document 0778
DOCN M94B0778
TI Bispecific antibodies recruiting cellular effectors (Meeting abstract).
DT 9412
AU Thielemans K; Lab. of Physiology-Immunology, Vrije Universiteit Brussel,
B-1090; Brussels, Belgium
SO EACR-12: 12th Biennial Meeting of the European Association for Cancer
Research. April 4-7, 1993, Brussels, Belgium, 1993.. Unique Identifier :
AIDSLINE ICDB/94697527
AB The idea to target T lymphocytes toward tumor cells has been tested
extensively and successfully by many laboratories. Our laboratory has
evaluated this attractive approach in vivo. We have developed bispecific
antibodies by hybrid-hybridoma technique, with dual specificity: the
murine CD3 complex and the idiotype (tumor specific antigen) of the
surface expressed IgM on two murine B-cell lymphomas. Since the primary
goal of our experiments was to evaluate the therapeutic potential of
this approach in vivo, we have invested great efforts in the generation
of proper control reagents. Using the aggressive 38C13 lymphoma of C3H
origin, we showed that bispecific antibodies could cure a significant
number of tumor-bearing animals. Animals with even a lower tumor burden
were not protected with any of the control antibodies (bi- or univalent
class-matched anti-idiotype mAb, bi- or univalent anti-CD3 mAb).
Tumor-bearing C3H/HeJ mice (not able to perform FcR-dependent ADCC)
could also be successfully treated. Animals in which we had induced
allo-sensitized effector T cells showed a much higher cure rate in
comparison with the experiments in untreated animals. Further evidence
that the therapeutic effect was T-cell-mediated and dependent on the
bridge formation between tumor cells and T cells, was obtained by using
a tumor-antigen negative variant of the 38C13 tumor line and by using a
mixture of a T-cell binding/nontumor-cell binding antibody plus a
tumor-cell binding/nonT-cell binding antibody. Similar results were
obtained with the BCL1 lymphoma model in BALB/c mice. The efficacy of
the bispecific antibodies was dependent on both tumor load and dose.
Repeated injections of bispecific antibodies could cure more mice than a
single injection. Treatment of tumor-bearing mice in which either CD4+,
CD8+ or both subsets had been depleted, clearly indicated the
T-cell-mediated effect and the contribution of both subsets to the tumor
eradicating mechanism. Taken together, our data indicate that it is
indeed possible to recruit and focus T cells against a given target in
vivo. Ongoing experiments explore the T-cell-mediated mechanism and the
potential improvement of our results by combining two bispecific
antibodies which will activate the T cells at the tumor site via CD3 and
CD28.
DE Animal Antibodies/*ADMINISTRATION & DOSAGE CD4-CD8 Ratio
*Immunotherapy Lymphoma/IMMUNOLOGY/*THERAPY Mice Mice, Inbred BALB C
Mice, Inbred C3H T-Lymphocytes/IMMUNOLOGY MEETING ABSTRACT
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).