T-cell activation and B-cell depletion in chimpanzees treated with a bispecific anti-CD19/anti-CD3 single-chain antibody construct

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Item Type:	Article
Title:	T-cell activation and B-cell depletion in chimpanzees treated with a bispecific anti-CD19/anti-CD3 single-chain antibody construct
Creators Name:	Schlereth, B., Quadt, C., Dreier, T., Kufer, P., Lorenczewski, G., Prang, N., Brandl, C., Lippold, S., Cobb, K., Brasky, K., Leo, E., Bargou, R., Murthy, K. and Baeuerle, P.A.
Abstract:	BscCD19xCD3 is a bispecific single-chain antibody construct with exceptional cytotoxic potency in vitro and in vivo. Here, we have investigated the biological activity of bscCD19xCD3 in chimpanzee, the only animal species identified in which bscCD19xCD3 showed bispecific binding, redirected B-cell lysis and cytokine production comparable to human cells. Pharmacokinetic analysis following 2-h intravenous infusion of 0.06, 0.1 or 0.12 mug/kg of bscCD19xCD3 as part of a dose escalation study in a single female chimpanzee revealed a half-life of approximately 2 h and elimination of the bispecific antibody from circulation within approximately 8 h after the end of infusion. This short exposure to bscCD19xCD3 elicited a transient increase in serum levels of IFNgamma, IL-6, IL-2, soluble CD25, and transiently upregulated expression of CD69 and MHC class II on CD8-positive cells. Cytokine release and upregulation of T-cell activation markers were not observed with vehicle controls. A multiple-dose study using 5 weekly doses of 0.1 mug/kg in two animals also showed transient cytokine release and an activation of peripheral T cells with a first-dose effect, accompanied by a transient lymphopenia. While oscillations of T-cell counts were relatively even during repeated treatments, the amplitudes of peripheral B cells declined with every infusion, which was not observed in a vehicle control animal. Our data show that bscCD19xCD3 can be safely administered to chimpanzees at dose levels that cause fully reversible T-cell activation and, despite a very short exposure time, cumulative loss of peripheral B lymphocytes. A clinical trial testing prolonged administration of bscCD19xCD3 (MT103) for improving efficacy is currently ongoing.
Keywords:	B-Lymphocytes, Bispecific Antibodies, CD19 Antigens, CD3 Antigens, Cultured Cells, Flow Cytometry, Immunologic Cytotoxicity Tests, Immunotherapy, Lymphocyte Activation, Lymphocyte Depletion, Mononuclear Leukocytes, Pan troglodytes, T-Lymphocytes, Tumor Cell Line, Animals
Source:	Cancer Immunology Immunotherapy
ISSN:	0340-7004
Publisher:	Springer
Volume:	55
Page Range:	503-514
Date:	May 2006
Official Publication:	https://doi.org/10.1007/s00262-005-0001-1
PubMed:	View item in PubMed

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