Acute myelogenous leukemia (AML) currently kills the majority of afflicted patients despite treatment with combination chemotherapy and allogeneic stem cell transplantation (SCT). Radiolabeled anti-CD45 monoclonal antibodies (Ab) have been shown to improve outcomes for AML in the setting of SCT, but toxicity remains high and cure rates are suboptimal. The objective of this research proposal is to maximize the cure rate of AML using a novel approach employing pretargeted radioimmunotherapy (PRIT) with genetically engineered bispecific antibodies.
In Aim 1, we will engineer, express, and purify anti-CD45 x anti-ligand bispecific Abs (scFv2-iFabs) that bind covalently and irreversibly to radiometal ligands.
In Aim 2, we will assess the binding characteristics of anti-CD45 x anti-ligand bispecific Abs (scFv2-iFabs) for CD45 antigen and for radiometal ligand chelates in vitro.
In Aim 3, we will compare and contrast the pharmacokinetics and biodistributions of pretargeted radioimmunotherapy using the novel molecularly engineered anti-CD45 x anti- ligand bispecific Abs (scFv2-iFabs) with our current gold standard method of PRIT using a streptavidin-biotin pretargeting method. Comparisons will be made in both an AML xenograft model and in a disseminated model of AML.
In Aim 4, we will compare and contrast the therapeutic efficacy of pretargeted RIT using the streptavidin-biotin approach with the novel bispecific anti-CD45 x anti-ligand bispecific antibody approach in both xenograft and disseminated AML models.
In Aim 5, we will investigate the toxicity and efficacy of combination therapy using anti-CD45 bispecific Ab pretargeting, with and without cytotoxic chemotherapy, in a disseminated model of human AML in SCID mice. We hypothesize that the novel bispecific "pretargeted" RIT strategy defined in this proposal will amplify the amount of radiation delivered to AML cells, decrease the radiation delivered to the liver, lungs, and other normal organs, improve remission and cure rates, prolong survival, and markedly attenuate toxicities compared to conventional RIT and to streptavidin-biotin PRIT. We anticipate rapid translation of the results of these preclinical experiments into our clinical RIT program for AML.

Public Health Relevance

Acute myelogenous leukemia (AML) develops in 13,290 Americans and kills 8,820 of them each year despite treatment with chemotherapy and stem cell transplantation. In this project, we plan to improve the cure rate of AML by targeting radionuclides to the CD45 antigen expressed on AML using a new method called pretargeted radioimmunotherapy using bispecific antibodies. Although this grant is specifically focused on AML, the treatment being developed can also be applied to other CD45- expressing malignancies, including other types of leukemia, myelodysplasia, and non-Hodgkin's lymphoma, that affect a total of more than 120,000 Americans each year. We anticipate that this approach will cure more patients and cause fewer toxicities than currently available therapies.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Merritt, William D
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Fred Hutchinson Cancer Research Center
United States
Zip Code
Palanca-Wessels, Maria Corinna; Press, Oliver W (2014) Advances in the treatment of hematologic malignancies using immunoconjugates. Blood 123:2293-301
Balkin, Ethan R; Kenoyer, Aimee; Orozco, Johnnie J et al. (2014) In vivo localization of ??Y and ยน??Lu radioimmunoconjugates using Cerenkov luminescence imaging in a disseminated murine leukemia model. Cancer Res 74:5846-54
Orozco, Johnnie J; Back, Tom; Kenoyer, Aimee et al. (2013) Anti-CD45 radioimmunotherapy using (211)At with bone marrow transplantation prolongs survival in a disseminated murine leukemia model. Blood 121:3759-67
Aweda, Tolulope A; Meares, Claude F (2012) Combination of isothermal titration calorimetry and time-resolved luminescence for high affinity antibody-ligand interaction thermodynamics and kinetics. Methods 56:145-53
Marquez, Bernadette V; Beck, Heather E; Aweda, Tolulope A et al. (2012) Enhancing peptide ligand binding to vascular endothelial growth factor by covalent bond formation. Bioconjug Chem 23:1080-9
Aweda, Tolulope A; Eskandari, Vahid; Kukis, David L et al. (2011) New covalent capture probes for imaging and therapy, based on a combination of binding affinity and disulfide bond formation. Bioconjug Chem 22:1479-83
Pagel, John M; Kenoyer, Aimee L; Back, Tom et al. (2011) Anti-CD45 pretargeted radioimmunotherapy using bismuth-213: high rates of complete remission and long-term survival in a mouse myeloid leukemia xenograft model. Blood 118:703-11
Palanca-Wessels, M Corinna A; Press, Oliver W (2010) Improving the efficacy of radioimmunotherapy for non-Hodgkin lymphomas. Cancer 116:1126-33
Walter, Roland B; Press, Oliver W; Pagel, John M (2010) Pretargeted radioimmunotherapy for hematologic and other malignancies. Cancer Biother Radiopharm 25:125-42
Aweda, Tolulope A; Beck, Heather E; Wu, Anna M et al. (2010) Rates and equilibria for probe capture by an antibody with infinite affinity. Bioconjug Chem 21:784-91

Showing the most recent 10 out of 11 publications