PET and SPECT Imaging of Macrophages in the Tumor Stroma: An Update

Area of Science:

• Oncology
• Immunology
• Medical Imaging

Background:

• Tumor-associated macrophages (TAMs) are crucial immune cells influencing tumor progression and treatment outcomes.
• Traditional TAM detection methods like biopsy are invasive and lack whole-body dynamic monitoring capabilities.
• Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) offer non-invasive imaging alternatives.

Purpose of the Study:

• To review advancements in TAM-targeted imaging probes for non-invasive tumor immune surveillance.
• To assess the potential of these probes in tumor targeting and therapeutic applications.
• To highlight challenges and future directions in TAM-targeted imaging for precision medicine.

Main Methods:

• Comprehensive review of literature on TAM-targeted imaging probes.
• Analysis of probes targeting cell surface markers (e.g., CD206), metabolic/functional markers (e.g., TSPO, CCR2), and multifunctional nanoprobes.
• Evaluation of theragnostic potential in preclinical and early clinical studies.

Main Results:

• Various TAM-specific biomarkers (CD206, TSPO, CCR2) are targeted by advanced imaging probes.
• Probes like ⁶⁸Ga-NOTA-anti-CD206 and ⁶⁴Cu-Macrin demonstrate high specificity and theragnostic potential.
• Challenges include target heterogeneity, off-target effects, and clinical translation hurdles.

Conclusions:

• TAM-targeted imaging offers a non-invasive approach for monitoring tumor immunity and guiding therapy.
• Further development of multi-target probes and multimodal imaging is essential for clinical translation.
• Optimized TAM imaging will enhance precision medicine and personalize cancer treatment strategies.