Depicting adoptive immunotherapy for prostate cancer in an animal model with magnetic resonance imaging
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Updated: Jun 8, 2026
Multianimal Magnetic Resonance Imaging for Tumor Measurements in Pancreatic Cancer Mouse Models
Published on: February 3, 2026
Reinhard Meier1, Daniel Golovko, Sidhartha Tavri
1Department of Radiology, Technical University of Munich, Munich, Germany.
Abstract:
Genetically modified natural killer (NK) cells that recognize tumor-associated surface antigens have recently shown promise as a novel approach for cancer immunotherapy. To determine NK cell therapy response early, a real-time, noninvasive method to quantify NK cell homing to the tumor is desirable. The purpose of this study was to evaluate if MR imaging could provide a noninvasive, in vivo diagnosis of NK cell accumulation in epithelial cell adhesion molecule (EpCAM)-positive prostate cancers in a rat xenograft model. Genetically engineered NK-92-scFv(MOC31)-ζ cells, which express a chimeric antigen receptor specific to the tumor-associated EpCAM antigen, and nontargeted NK-92 cells were labeled with superparamagnetic particles of iron-oxides (SPIO) ferumoxides. Twelve athymic rats with implanted EpCAM positive DU145 prostate cancers received intravenous injections of 1.5×10(7) SPIO labeled NK-92 and NK-92-scFv(MOC31)-ζ cells. EpCAM-positive prostate cancers demonstrated a progressive and a significant decline in contrast-to-noise-ratio data at 1 and 24 h after injection of SPIO-labeled NK-92-scFv(MOC31)-ζ cells. Conversely, tumor contrast-to-noise-ratio data did not change significantly after injection of SPIO-labeled parental NK-92 cells. Histopathology confirmed an accumulation of the genetically engineered NK-92-scFv(MOC31)-ζ cells in prostate cancers. Thus, the presence or absence of a tumor accumulation of therapeutic NK cells can be monitored with cellular MR imaging. EpCAM-directed, SPIO labeled NK-92-scFv(MOC31)-ζ cells accumulate in EpCAM-positive prostate cancers.
Insights
Magnetic Resonance (MR) imaging can noninvasively monitor genetically engineered natural killer (NK) cells targeting EpCAM-positive prostate cancers. This technique quantifies NK cell accumulation in tumors, aiding early cancer immunotherapy response assessment.
Area of Science:
- Oncology
- Immunotherapy
- Biomedical Imaging
Background:
- Genetically modified natural killer (NK) cells show promise in cancer immunotherapy by targeting tumor antigens.
- Noninvasive, real-time methods are needed to assess NK cell homing to tumors for therapy response prediction.
Purpose of the Study:
- To evaluate if MR imaging can noninvasively diagnose NK cell accumulation in EpCAM-positive prostate cancer xenografts.
- To assess the efficacy of genetically engineered NK cells targeting EpCAM in vivo.
Main Methods:
- NK-92 cells engineered with a chimeric antigen receptor (NK-92-scFv(MOC31)-ζ) targeting EpCAM were labeled with SPIO ferumoxides.
- These labeled cells and control NK-92 cells were injected intravenously into rats with EpCAM-positive prostate cancer xenografts.
- MR imaging was used to monitor SPIO-labeled NK cell accumulation by measuring changes in contrast-to-noise ratio (CNR) in tumors.
Main Results:
- A significant decline in tumor CNR was observed after injecting SPIO-labeled NK-92-scFv(MOC31)-ζ cells, indicating accumulation.
- No significant CNR change occurred in tumors after injecting SPIO-labeled parental NK-92 cells.
- Histopathology confirmed the accumulation of genetically engineered NK cells in prostate tumors.
Conclusions:
- Cellular MR imaging can monitor the tumor accumulation of therapeutic NK cells.
- EpCAM-directed, SPIO-labeled NK-92-scFv(MOC31)-ζ cells effectively home to EpCAM-positive prostate cancers.
- MR imaging provides a noninvasive method for assessing NK cell therapy in prostate cancer models.
