Multiparametric MRI of early tumor response to immune checkpoint blockade in metastatic melanoma.

Abstract:: BACKGROUND: Immune checkpoint inhibitors are now standard of care treatment for many cancers. Treatment failure in metastatic melanoma is often due to tumor heterogeneity, which is not easily captured by conventional CT or tumor biopsy. The aim of this prospective study was to investigate early microstructural and functional changes within melanoma metastases following immune checkpoint blockade using multiparametric MRI. METHODS: Fifteen treatment-naïve metastatic melanoma patients (total 27 measurable target lesions) were imaged at baseline and following 3 and 12 weeks of treatment on immune checkpoint inhibitors using: T2-weighted imaging, diffusion kurtosis imaging, and dynamic contrast-enhanced MRI. Treatment timepoint changes in tumor cellularity, vascularity, and heterogeneity within individual metastases were evaluated and correlated to the clinical outcome in each patient based on Response Evaluation Criteria in Solid Tumors V.1.1 at 1 year. RESULTS: Differential tumor growth kinetics in response to immune checkpoint blockade were measured in individual metastases within the same patient, demonstrating significant intertumoral heterogeneity in some patients. Early detection of tumor cell death or cell loss measured by a significant increase in the apparent diffusivity (Dapp) (p

Authors:: D Lau, MA McLean, AN Priest, AB Gill, F Scott, I Patterson, B Carmo, F Riemer, JD Kaggie, A Frary, D Milne, C Booth, A Lewis, M Sulikowski, L Brown, J-M Lapointe, L Aloj, MJ Graves, KM Brindle, PG Corrie, FA Gallagher

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