Research ArticleCancer Imaging

68Ga-DOTA-GGNle-CycMSHhex targets the melanocortin-1 receptor for melanoma imaging

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Science Translational Medicine  07 Nov 2018:
Vol. 10, Issue 466, eaau4445
DOI: 10.1126/scitranslmed.aau4445

Figures

  • Fig. 1 Schematic structures and in vitro competitive binding curves.

    (A) Schematic structures of DOTA-GGNle-CycMSHhex and Cy5.5-GGNle-CycMSHhex. (B) In vitro competitive binding curves of DOTA-GGNle-CycMSHhex and Cy5.5-GGNle-CycMSHhex using B16/F10 and M21 melanoma cells. The IC50 values of DOTA-GGNle-CycMSHhex were 2.1 ± 0.3 nM (*, black) and 1.1 ± 0.2 nM (•, pink) on B16/F10 and M21 melanoma cells, respectively. The IC50 values of Cy5.5-GGNle-CycMSHhex were 7.1 ± 0.1 nM (□, green) and 2.6 ± 0.3 nM (○, red) on B16/F10 and M21 melanoma cells, respectively.

  • Fig. 2 UV and radioactive HPLC profiles.

    (A) Ultraviolet (UV) HPLC profile of DOTA-GGNle-CycMSHhex (retention time, TR = 15.7 min) and (B) radioactive HPLC profile of 68Ga-DOTA-GGNle-CycMSHhex (TR = 16.9 min). (C) Serum stability of 68Ga-DOTA-GGNle-CycMSHhex at 1 hour after incubation (TR = 16.4 min). (D) Radioactive HPLC profile of the urine sample of a normal C57 mouse at 2 hours after injection of 68Ga-DOTA-GGNle-CycMSHhex (TR = 16.9 min). Arrows indicate the original compounds of DOTA-GGNle-CycMSHhex (A) and 68Ga-DOTA-GGNle-CycMSHhex (B to D). Specific binding of 68Ga-DOTA-GGNle-CycMSHhex on (E) B16/F10 and (F) M21 melanoma cells with or without peptide blockade (P < 0.05).

  • Fig. 3 Fluorescence staining of MC1R.

    Fluorescence staining of (A) B16/F10 murine melanoma cells, (B) B16/F10 flank melanoma lesions, (C) B16/F10 pulmonary metastatic melanoma lesions, (D) M21 human melanoma cells, and (E) M21-xenografted flank melanoma lesions. Cells and melanoma tissues were stained with 1 μM Cy5.5-GGNle-CycMSHhex (red) in the presence or absence of 100 μM peptide blockade. The nuclei were stained with DAPI (blue). The microscopic images were acquired by confocal laser microscopy at 100× magnification. Scale bar, 20 μm.

  • Fig. 4 PET imaging of flank melanoma.

    Representative PET imaging of a live B16/F10 murine melanoma–bearing mouse (top) and a live M21 human melanoma–xenografted nude mouse (bottom) using 68Ga-DOTA-GGNle-CycMSHhex as an imaging probe at 0.5, 1, and 2 hours after injection. Melanoma lesions are highlighted with arrows on the images.

  • Fig. 5 PET imaging of pulmonary metastatic melanoma.

    Representative PET imaging of a live B16/F10 pulmonary metastatic melanoma–bearing mouse using 68Ga-DOTA-GGNle-CycMSHhex as an imaging probe at 0.5 and 1 hour after injection. Pulmonary metastatic melanoma lesions are highlighted with arrows on the images.

  • Fig. 6 PET imaging of patients with melanoma.

    Representative first-in-human PET studies on two patients with melanoma. Melanoma metastases in the brain, lung, connective tissue, and small intestine of patient 1 (A and C) were visualized by PET using 68Ga-GGNle-CycMSHhex. Melanoma metastases on the left leg of patient 2 (E) were imaged by PET using 68Ga-GGNle-CycMSHhex. 18F-FDG PET (B, D, and F) studies were performed on the same patients for comparisons. The melanoma metastases in brain (BM1 and BM2) were confirmed by MRI, and the metastasis in connective tissue (CM1) was confirmed by CT. Melanoma metastases are highlighted with arrows on the images. SUVbw, standardized uptake value based on body weight.

Tables

  • Table 1 Biodistribution of 68Ga-DOTA-GGNle-CycMSHhex on B16/F10 murine melanoma–bearing C57 mice.

    The data are presented as percent injected dose per gram (%ID/g) or as percent injected dose (%ID) (means ± SD, n = 4).

    Tissues0.5 hour1 hour2 hours1 hour
    NDP-MSH
    blockade
    %ID/g
    Tumor18.63 ±
    4.97
    24.27 ± 3.7411.61 ± 2.871.94 ± 0.51*
    Brain0.13 ± 0.020.07 ± 0.010.03 ± 0.010.09 ± 0.06
    Blood2.27 ± 0.320.83 ± 0.10.31 ± 0.060.98 ± 0.45
    Heart0.94 ± 0.060.36 ± 0.040.12 ± 0.020.35 ± 0.04
    Lung1.91 ± 0.220.87 ± 0.120.29 ± 0.020.73 ± 0.19
    Liver1.21 ± 0.080.79 ± 0.080.61 ± 0.060.69 ± 0.08
    Skin2.26 ± 0.121.23 ± 0.330.54 ± 0.190.8 ± 0.17
    Spleen0.75 ± 0.080.36 ± 0.050.33 ± 0.150.22 ± 0.15
    Stomach1.67 ± 0.870.91 ± 0.110.54 ± 0.160.49 ± 0.36
    Kidneys9.22 ± 1.387.78 ± 0.636.01 ± 0.915.98 ± 0.69
    Muscle0.44 ± 0.030.3 ± 0.050.13 ± 0.080.36 ± 0.24
    Pancreas0.44 ± 0.070.24 ± 0.050.11 ± 0.070.4 ± 0.19
    Bone0.98 ± 0.270.6 ± 0.130.24 ± 0.150.32 ± 0.22
    %ID
    Intestines1.32 ± 0.510.68 ± 0.110.59 ± 0.310.68 ± 0.31
    Urine71.62 ±
    11.72
    85.39 ± 3.7691.73 ± 0.2691.83 ±
    1.01
    Uptake ratio of tumor/
    normal tissue
    Tumor/blood8.2129.2437.451.98
    Tumor/
    kidney
    2.023.121.930.32
    Tumor/lung9.7527.9040.032.66
    Tumor/liver15.4030.7219.032.81
    Tumor/
    muscle
    42.3480.9089.315.39

    *P < 0.05, tumor uptake with or without peptide blockade at 1 hour after injection.

    • Table 2 Biodistribution of 68Ga-DOTA-GGNle-CycMSHhex on M21 human melanoma–xenografted nude mice.

      The data are presented as percent injected dose/gram (%ID/g) or as percent injected dose (%ID) (means ± SD, n = 4).

      Tissues0.5 hour1 hour2 hours1 hour
      NDP-MSH
      blockade
      % ID/g
      Tumor6.05 ± 0.836.07 ± 0.685.15 ± 0.781.02 ± 0.54*
      Brain0.09 ± 0.020.06 ± 0.010.04 ± 0.020.05 ± 0.02
      Blood1.78 ± 0.440.69 ± 0.190.41 ± 0.210.52 ± 0.12
      Heart0.80 ± 0.170.31 ± 0.030.17 ± 0.020.24 ± 0.07
      Lung1.86 ± 0.280.8 ± 0.10.3 ± 0.040.57 ± 0.09
      Liver0.97 ± 0.150.57 ± 0.030.45 ± 0.070.5 ± 0.03
      Skin2.0 ± 0.340.94 ± 0.210.62 ± 0.120.37 ± 0.23
      Spleen0.54 ± 0.040.36 ± 0.050.21 ± 0.090.28 ± 0.23
      Stomach0.80 ± 0.240.32 ± 0.070.46 ± 0.40.25 ± 0.07
      Kidneys6.61 ± 1.114.09 ± 0.493.74 ± 0.553.76 ± 0.39
      Muscle0.37 ± 0.10.15 ± 0.030.11 ± 0.030.08 ± 0.02
      Pancreas0.43 ± 0.160.2 ± 0.030.14 ± 0.050.19 ± 0.08
      Bone1.06 ± 0.30.37 ± 0.10.35 ± 0.110.26 ± 0.24
      % ID
      Intestines1.24 ± 0.360.68 ± 0.130.61 ± 0.270.51 ± 0.04
      Urine77.35 ± 4.0388.91 ± 0.6692.75 ± 1.1393.4 ± 1.34
      Uptake ratio of tumor/
      normal tissue
      Tumor/blood3.48.8012.561.96
      Tumor/
      kidney
      0.921.481.380.27
      Tumor/lung3.257.5917.171.79
      Tumor/liver6.2410.6511.442.04
      Tumor/
      muscle
      16.3540.4746.8212.75

      *P < 0.05, tumor uptake with or without peptide blockade at 1 hour after injection.

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