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Toxins 2018, 10(1), 32; https://doi.org/10.3390/toxins10010032

Development of a Deimmunized Bispecific Immunotoxin dDT2219 against B-Cell Malignancies

1
University of Minnesota Masonic Cancer Center, Section of Molecular Cancer Therapeutics, Therapeutic Radiology-Radiation Oncology, University of Minnesota, Minneapolis, MN 55455, USA
2
Department for Hematology and Oncology, University Hospital of Tuebingen, Medical Department 2, 72076 Tuebingen, Germany
3
Division of Hematology, Oncology, and Transplantation, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA
*
Author to whom correspondence should be addressed.
Received: 26 October 2017 / Revised: 16 December 2017 / Accepted: 31 December 2017 / Published: 6 January 2018
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Abstract

Diphtheria toxin (DT) related targeted toxins are effective in cancer treatment, but efficacy diminishes in time because of their immunogenic potential and/or former vaccinations. In order to overcome this limitation for DT2219, a promising bispecific targeted toxin which targets CD19 and CD22, we deimmunized the DT moiety, and thereby developed an exciting improved drug (dDT2219) which still has the potential to sufficiently target B-cell malignancies but also limits clearance because of its reduced immunogenicity. The DT moiety was modified by inducing point mutations in prominent positions on the molecular surface. The new engineered dDT2219 was tested for activity, efficacy, and specificity using functional assays, proliferation assays, and flow cytometry. Furthermore, 12 samples of Chronic Lymphatic Leukemia (CLL) patients were used to assess binding. Immunogenicity was determined using a BALB/c mouse model. dDT2219 was efficient and specific against B-cell malignancies such as Bukitt-Lymphoma cell lines Daudi and Raji. dDT2219 showed specific binding on targets and on CLL samples. Intraperitoneal vaccination of immune competent mice showed that even after multiple administrations with increasing doses, induction of neutralizing antibodies was significantly lower in the dDT2219 treated animal group. The new dDT2219 combines potent anti-tumor cell activity with a reduced immunogenicity. With regard to the frequent development of neutralizing antibodies after multiple administrations with immunotoxins, dDT2219 shows promise to overcome this limitation and thus might maintain effectiveness even after multiple treatment cycles. View Full-Text
Keywords: diphtheria toxin; B-cell malignancies CD19; CD22; deimmunized; immunotoxin; Key Contribution; The new dDT2219 targeted toxin combines potent anti-tumor cell activity with a reduced immunogenicity. diphtheria toxin; B-cell malignancies CD19; CD22; deimmunized; immunotoxin; Key Contribution; The new dDT2219 targeted toxin combines potent anti-tumor cell activity with a reduced immunogenicity.
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Schmohl, J.U.; Todhunter, D.; Taras, E.; Bachanova, V.; Vallera, D.A. Development of a Deimmunized Bispecific Immunotoxin dDT2219 against B-Cell Malignancies. Toxins 2018, 10, 32.

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