Related Experiment Video
Updated: Oct 8, 2025
Harnessing the Bioorthogonal Inverse Electron Demand Diels-Alder Cycloaddition for Pretargeted PET Imaging
Published on: February 3, 2015
Humanization, Radiolabeling and Biodistribution Studies of an IgG1-Type Antibody Targeting Uncomplexed PSA for
Joanna Strand1, Kjell Sjöström2, Urpo J Lamminmaki3
1Department of Oncology, Department of Clinical Sciences, Lund University, 22243 Lund, Sweden.
Abstract:
Metastatic castration-resistant prostate cancer is today incurable. Conventional imaging methods have limited detection, affecting their ability to give an accurate outcome prognosis, and current therapies for metastatic prostate cancer are insufficient. This inevitably leads to patients relapsing with castration-resistant prostate cancer. Targeting prostate-specific antigens whose expression is closely linked to the activity in the androgen receptor pathway, and thus the pathogenesis of prostate cancer, is a possible way to increase specificity and reduce off-target effects. We have humanized and evaluated radioimmunoconjugates of a previously murine antibody, m5A10, targeting PSA intended for theranostics of hormone-refractory prostate cancer. The humanized antibody h5A10 was expressed in mammalian HEK293 cells transfected with the nucleotide sequences for the heavy and light chains of the antibody. Cell culture medium was filtered and purified by Protein G chromatography, and the buffer was changed to PBS pH 7.4 by dialysis. Murine and humanized 5A10 were conjugated with p-SCN-Bn-CHX-A"-DTPA. Surface plasmon resonance was used to characterize the binding to PSA of the immunoconjugates. Immunoconjugates were labeled with either indium-111 or lutetium-177. Biodistribution studies of murine and humanized 5A10 were performed in mice with LNCaP xenografts. 5A10 was successfully humanized, and in vivo targeting showed specific binding in xenografts. The results thus give an excellent platform for further theranostic development of humanized 5A10 for clinical applications.
Insights
Researchers humanized an antibody targeting prostate-specific antigen (PSA) for improved imaging and therapy of metastatic castration-resistant prostate cancer. This new radioimmunoconjugate shows specific binding, offering a platform for theranostic development.
Area of Science:
- Oncology
- Immunology
- Radiochemistry
Background:
- Metastatic castration-resistant prostate cancer (mCRPC) remains incurable with current treatments.
- Conventional imaging lacks accuracy for prognosis in mCRPC.
- Prostate-specific antigen (PSA) targeting offers specificity for prostate cancer therapy.
Purpose of the Study:
- To humanize the murine antibody m5A10 for targeting PSA.
- To develop radioimmunoconjugates for theranostic applications in mCRPC.
- To evaluate the efficacy and specificity of the humanized antibody.
Main Methods:
- Humanization of the m5A10 antibody (h5A10) using mammalian cell expression.
- Conjugation of antibodies with p-SCN-Bn-CHX-A"-DTPA.
- Radiolabeling with Indium-111 or Lutetium-177 for imaging and therapy.
- Surface plasmon resonance for binding characterization.
- Biodistribution studies in LNCaP xenograft mouse models.
Main Results:
- Successful humanization of the m5A10 antibody to h5A10.
- Demonstrated specific in vivo targeting of PSA in xenografts.
- Characterized binding affinity and specificity of immunoconjugates.
Conclusions:
- Humanized 5A10 antibody is a viable candidate for prostate cancer theranostics.
- The developed radioimmunoconjugates show promise for clinical translation.
- This approach offers a potential improvement over existing mCRPC therapies.
