Disulfide-stabilized diabody antiCD19/antiCD3 exceeds its parental antibody in tumor-targeting activity.
BACKGROUND
A diabody is a bispecific antibody that is capable of recruiting a polyclonal T cell to antibody target-expressing tumor cells. However, the two chains of diabodies tend to dissociate because they are integrated non-covalently. Therefore, it is necessary to remodel the diabody to increase its stability in order to enhance the antitumor activity.


METHODS
We constructed an antiCD3×antiCD19 diabody with one binding site for the T cell antigen receptor (TCRCD3) and the other for the B cell-specific antigen (CD19) by recombinant gene engineering technology. Cysteine residues were introduced into the V domains of the anti-CD3 segment. The stability and cytotoxicity of the two diabodies were compared in vitro and vivo.


RESULTS
The disulfide-stabilized (ds) diabodies produced by Escherichia coli were secreted with high yields in a fully active form without a decrease in affinity. Compared with the parental diabody, the disulfide-stabilized (ds) diabody proved more stable in vitro and in vivo without reducing binding affinity. Both were able to effectively eliminate human lymphoma Raji cells by redirecting T lymphocytes in vitro and in vivo, but the ds diabody was more effective in inhibiting the growth of xenografts transplanted in BALB/C nude mice.


CONCLUSIONS
The antiCD3×antiCD19 ds diabody is more suitable for a controlled polyclonal T cell therapy of human CD19-positive B cell malignancies than its parental diabody.
State key Laboratory of Experimental Hematology, Institute of Hematology and Hospital of Blood Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China.
Li
L
Wei
Fan
F
Dongmei
Yang
Y
Ming
Shi
S
Ruizan
Yan
Y
Yan
Jiang
J
Linlin
Yan
Y
Cihui
Li
L
Shuangjing
Wang
W
Min
Wang
W
Jianxiang
Xiong
X
Dongsheng
D000818:Animals; D018033:Antibodies, Bispecific / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D000915:Antibody Affinity; D018941:Antigens, CD19 / Q000276:immunology*; D017252:CD3 Complex / Q000276:immunology*; D005434:Flow Cytometry; D005818:Genetic Engineering; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D016393:Lymphoma, B-Cell / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D023041:Xenograft Model Antitumor Assays
D018033:Antibodies, Bispecific; D018941:Antigens, CD19; D017252:CD3 Complex