MicroPET/CT Imaging of AXL Downregulation by HSP90 Inhibition in Triple-Negative Breast Cancer

Figure 2

MicroPET/CT imaging of MDA-MB-231 tumors with ⁶⁴Cu-anti-hAXL, autoradiography, and biodistribution. (a) Representative microPET/CT images of MDA-MB-231 tumor xenografts in mice 24 h after intravenous injection of either ⁶⁴Cu-anti-hAXL or ⁶⁴Cu-IgG control. Tumor uptake of ⁶⁴Cu-anti-hAXL, but not ⁶⁴Cu-IgG, was clearly visualized (left). White arrows: tumors. MIP: maximal intensity projection. Quantitative PET analysis of tumor uptake of each radiotracer ( = 3/group, right). Tumors of the mice that received ⁶⁴Cu-anti-hAXL had significantly higher uptake of the radiotracer than tumors of the mice that received ⁶⁴Cu-IgG (SUV: 143.20 ± 8.97 versus 39.34 ± 0.85, < 0.0001). (b) Representative autoradiographs of MDA-MB-231 tumor sections obtained 24 h after intravenous injection of ⁶⁴Cu-anti-hAXL or ⁶⁴Cu-IgG. (c) Biodistribution of radiotracer in mice 24 h after intravenous injection of ⁶⁴Cu-anti-hAXL or ⁶⁴Cu-IgG control ( = 3/group). Uptake of ⁶⁴Cu-anti-hAXL in MDA-MB-231 tumors was about three times higher than that of ⁶⁴Cu-IgG (14.48 ± 2.88 versus 5.24 ± 0.76 %ID/g, P < 0.001). Inset: comparison of ratios of tumor-to-muscle and tumor-to-blood uptake of ⁶⁴Cu-anti-hAXL and ⁶⁴Cu-IgG ( < 0.001, < 0.01).

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