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Magnetic Resonance Imaging of Tumor Associated Macrophages: Clinical Translation.

Magnetic Resonance Imaging of Tumor Associated Macrophages: Clinical Translation. Clinical cancer research : an official journal of the American Association for Cancer Research Aghighi, M. n., Theruvath, A. J., Pareek, A. n., Pisani, L. n., Alford, R. n., Muehe, A. M., Sethi, T. K., Holdsworth, S. J., Hazard, F. K., Gratzinger, D. n., Luna-Fineman, S. n., Advani, R. H., Spunt, S. L., Daldrup-Link, H. E. 2018

Abstract

Tumor associated macrophages (TAM) in malignant tumors have been linked to tumor aggressiveness and represent a new target for cancer immunotherapy. As new TAM-targeted immunotherapies are entering clinical trials, it is important to detect and quantify TAM with non-invasive imaging techniques. The purpose of this study was to determine if ferumoxytol-enhanced MRI can detect TAM in lymphomas and bone sarcomas of pediatric patients and young adults.In a first-in-patient, IRB-approved prospective clinical trial, 25 pediatric and young adult patients with lymphoma or bone sarcoma underwent ferumoxytol-enhanced MRI. To confirm ferumoxytol enhancement, five pilot patients (2 lymphoma, 3 bone sarcoma) underwent pre- and post-contrast MRI. Subsequently, 20 patients (10 lymphoma, 10 bone sarcoma) underwent ferumoxytol-enhanced MRI 24-48 hours after intravenous injection, followed by tumor biopsy/resection and macrophage staining. To determine if ferumoxytol-MRI can differentiate tumors with different TAM content, we compared T2* relaxation times of lymphomas and bone sarcomas. Tumor T2* values of 20 patients were correlated with CD68+ and CD163+ TAM quantities on histopathology.Significant ferumoxytol tumor enhancement was noted on post-contrast scans compared to pre-contrast scans (P = 0.036). Bone sarcomas and lymphomas demonstrated significantly different MRI enhancement and TAM density (P < 0.05). Within each tumor group, T2* signal enhancement on MR images correlated significantly with the density of CD68+ and CD163+ TAM (P < 0.05).Ferumoxytol-enhanced MRI is immediately clinically applicable and could be used to stratify patients with TAM-rich tumors to immune-targeted therapies and to monitor tumor response to these therapies.

View details for PubMedID 29764855