1. Integrin-targeted quantitative optoacoustic imaging with MRI correlation for monitoring a BRAF/MEK inhibitor combination therapy in a murine model of human melanoma.
- Author
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Kazmierczak, Philipp M., Burton, Neal C., Keinrath, Georg, Hirner-Eppeneder, Heidrun, Schneider, Moritz J., Eschbach, Ralf S., Heimer, Maurice, Solyanik, Olga, Todica, Andrei, Reiser, Maximilian F., Ricke, Jens, and Cyran, Clemens C.
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MELANOMA ,NEUROENDOCRINE tumors ,DYSPLASTIC nevus syndrome ,PHOTOACOUSTIC spectroscopy ,XENOGRAFTS ,IMMUNOHISTOCHEMISTRY - Abstract
Purpose: To investigate α
v β3 -integrin-targeted optoacoustic imaging and MRI for monitoring a BRAF/MEK inhibitor combination therapy in a murine model of human melanoma. Materials and methods: Human BRAF V600E-positive melanoma xenograft (A375)-bearing Balb/c nude mice (n = 10) were imaged before (day 0) and after (day 7) a BRAF/MEK inhibitor combination therapy (encorafenib, 1.3 mg/kg/d; binimetinib, 0.6 mg/kg/d, n = 5) or placebo (n = 5), respectively. Optoacoustic imaging was performed on a preclinical system unenhanced and 5 h after i. v. injection of an αv β3 -integrin-targeted fluorescent probe. The αv β3 -integrin-specific tumor signal was derived by spectral unmixing. For morphology-based tumor response assessments, T2w MRI data sets were acquired on a clinical 3 Tesla scanner. The imaging results were validated by multiparametric immunohistochemistry (ß3 –integrin expression, CD31 –microvascular density, Ki-67 –proliferation). Results: The αv β3 -integrin-specific tumor signal was significantly reduced under therapy, showing a unidirectional decline in all animals (from 7.98±2.22 to 1.67±1.30; p = 0.043). No significant signal change was observed in the control group (from 6.60±6.51 to 3.67±1.93; p = 0.500). Immunohistochemistry revealed a significantly lower integrin expression (ß3 : 0.20±0.02 vs. 0.39±0.05; p = 0.008) and microvascular density (CD31: 119±15 vs. 292±49; p = 0.008) in the therapy group. Tumor volumes increased with no significant intergroup difference (therapy: +107±42 mm3 ; control +112±44mm3 , p = 0.841). In vivo blocking studies with αv β3 -integrin antagonist cilengitide confirmed the target specificity of the fluorescent probe. Conclusions: αv β3 -integrin-targeted optoacoustic imaging allowed for the early non-invasive monitoring of a BRAF/MEK inhibitor combination therapy in a murine model of human melanoma, adding molecular information on tumor receptor status to morphology-based tumor response criteria. [ABSTRACT FROM AUTHOR]- Published
- 2018
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