Alternative therapies for drug refractory B cell malignancies are urgently needed. We used advances last cycle to develop a new class of recombinant bispecific targeted toxin with expanded ability to recognize a wider range of B cell cancers. With funding from this grant, we discovered that bispecific targeted toxins could be made by fusing two repeating scFv subunits creating a bispecific ligand directed toxin and they had superior activity over monospecific targeted toxins. We brought the drug to clinical trial for leukemia. Findings are encouraging, but preliminary data indicates that toxin immunogenicity will be a problem as anticipated. Multiple dosing is required to obtain sustained remissions and this generates anti-toxin antibodies that impact drug efficacy. To this end, we have found an important new and successful way to deimmunize our toxin that may have implications for deimmunizing other molecules.
In aim 1, we propose to study this deimmunization. Funding from this proposal has also led to the development of a very different targeted toxin that has the ability to target cancer stem cells. Current theory dictates that cancer cells differentiate as do normal cells. The cancer cell population consists of a small cohort of less differentiated, self renewing, tumor initiating stem cells and a larger cohort of more differentiated tumor cells. More differentiated cells are more susceptible to chemotherapy and the minor fraction of less differentiated cancer stem cells are more drug resistant, thus contributing to drug refractory relapse in cancer. We have created a new targeted toxin that targets cancer stem cells and clearly has therapeutic efficacy in systemic mouse models of cancer. The agent has the advantage of working against a variety of different cancers.
In aim 2, we propose to study this new strategy of targeting tumor stem cells.
Aim 1 relates to Aim 2 since the deimmunization strategies are used to construct anti-stem cell targeted toxins as well.

Public Health Relevance

Our group has discovered a new class of biological drugs called bispecific targeted toxins that show superiority over their monospecific counterparts and can be genetically modified to address some of the major problems in the field and we have proven that multiple treatments with these drugs are highly effective against systemic cancer in animals resulting in long-term disease free survivors. In this proposal, we will be addressing some of the major issues with these drugs. We will be investigating improvements in reducing their immunogenicity and destroying the most important drug resistant cells, cancer stem cells.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Cancer Immunopathology and Immunotherapy Study Section (CII)
Program Officer
Welch, Anthony R
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Minnesota Twin Cities
Schools of Medicine
United States
Zip Code
Oh, Felix; Todhunter, Deborah; Taras, Elizabeth et al. (2018) Targeting EGFR and uPAR on human rhabdomyosarcoma, osteosarcoma, and ovarian adenocarcinoma with a bispecific ligand-directed toxin. Clin Pharmacol 10:113-121
Schmohl, Joerg U; Todhunter, Deborah; Taras, Elizabeth et al. (2018) Development of a Deimmunized Bispecific Immunotoxin dDT2219 against B-Cell Malignancies. Toxins (Basel) 10:
Pilbeam, Kristy; Wang, Hongbo; Taras, Elizabeth et al. (2018) Targeting pediatric sarcoma with a bispecific ligand immunotoxin targeting urokinase and epidermal growth factor receptors. Oncotarget 9:11938-11947
Borgatti, Antonella; Koopmeiners, Joseph S; Sarver, Aaron L et al. (2017) Safe and Effective Sarcoma Therapy through Bispecific Targeting of EGFR and uPAR. Mol Cancer Ther 16:956-965
Schmohl, Jörg U; Felices, Martin; Oh, Felix et al. (2017) Engineering of Anti-CD133 Trispecific Molecule Capable of Inducing NK Expansion and Driving Antibody-Dependent Cell-Mediated Cytotoxicity. Cancer Res Treat 49:1140-1152
Schmohl, J U; Gleason, M K; Dougherty, P R et al. (2016) Heterodimeric Bispecific Single Chain Variable Fragments (scFv) Killer Engagers (BiKEs) Enhance NK-cell Activity Against CD133+ Colorectal Cancer Cells. Target Oncol 11:353-61
Schmohl, Joerg U; Felices, Martin; Todhunter, Deborah et al. (2016) Tetraspecific scFv construct provides NK cell mediated ADCC and self-sustaining stimuli via insertion of IL-15 as a cross-linker. Oncotarget 7:73830-73844
Schmohl, Joerg U; Felices, Martin; Taras, Elizabeth et al. (2016) Enhanced ADCC and NK Cell Activation of an Anticarcinoma Bispecific Antibody by Genetic Insertion of a Modified IL-15 Cross-linker. Mol Ther 24:1312-22
Vallera, Daniel A; Felices, Martin; McElmurry, Ron et al. (2016) IL15 Trispecific Killer Engagers (TriKE) Make Natural Killer Cells Specific to CD33+ Targets While Also Inducing Persistence, In Vivo Expansion, and Enhanced Function. Clin Cancer Res 22:3440-50
Schmohl, Joerg U; Todhunter, Deborah; Oh, Seung et al. (2015) Mutagenic Deimmunization of Diphtheria Toxin for Use in Biologic Drug Development. Toxins (Basel) 7:4067-82

Showing the most recent 10 out of 85 publications