An 89Zr-HDL PET Tracer Monitors Response to a CSF1R Inhibitor.
The immune function within the tumor microenvironment has become a prominent therapeutic target, with tumor-associated macrophages (TAMs) playing a critical role in immune suppression. We propose an 89Zr-labeled high-density lipoprotein (89Zr-HDL) nanotracer as a means of monitoring response to immunotherapy. Methods: Female MMTV-PyMT mice were treated with pexidartinib, a colony-stimulating factor 1 receptor (CSF1R) inhibitor, to reduce TAM density. The accumulation of 89Zr-HDL within the tumor was assessed using PET/CT imaging and autoradiography, whereas TAM burden was determined using immunofluorescence. Results: A significant reduction in 89Zr-HDL accumulation was observed in PET/CT images, with 2.9% ± 0.3% and 3.7% ± 0.2% injected dose/g for the pexidartinib- and vehicle-treated mice, respectively. This reduction was corroborated ex vivo and correlated with decreased TAM density. Conclusion: These results support the potential use of 89Zr-HDL nanoparticles as a PET tracer to quickly monitor the response to CSF1R inhibitors and other therapeutic strategies targeting TAMs.
['Mason|Christian A|CA|', 'Kossatz|Susanne|S|', 'Carter|Lukas M|LM|', 'Pirovano|Giacomo|G|', 'Brand|Christian|C|', 'Guru|Navjot|N|', 'Pérez-Medina|Carlos|C|', 'Lewis|Jason S|JS|', 'Mulder|Willem J M|WJM|', 'Reiner|Thomas|T|']
D000631:Aminopyridines D000818:Animals D005260:Female D008075:Lipoproteins, HDL D008264:Macrophages D051379:Mice D000072078:Positron Emission Tomography Computed Tomography D011758:Pyrroles D011849:Radioactive Tracers D011868:Radioisotopes D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor D014018:Tissue Distribution D015040:Zirconium
CSF1R inhibitor tumor-associated macrophages immunotherapy PET/CT imaging HDL