These simple, robust kits shall allow hospitals with different generators to participate in clinical studies of <sup>68</sup>Ga-RM2 for screening of GRPR-expressing prostate tumors.
Here we investigated the potential of a novel DOTHA<sub>2</sub>-conjugated, <sup>64</sup>Cu-radiolabeled GRPR peptide antagonist, [D-Phe<sup>6</sup>-Sta<sup>13</sup>-Leu<sup>14</sup>-NH<sub>2</sub>]bombesin(6-14) (DOTHA<sub>2</sub>-PEG-RM26) to visualize prostate tumors by PET imaging.
Preliminary in vivo studies of 64Cu-6 in NMRI nu/nu mice, bearing the human prostate tumor PC-3 showed an accumulation of the conjugate in the tumor (2.25 +/- 0.13 SUV, 12.5 min p.i.; 0.94 +/- 0.05 SUV, 55 min p.i.) and allowed a clear visualization of the gastrin-releasing peptide receptor distribution by positron emission tomography (PET).
Because of tumor heterogeneity, the high number of receptors in the PC-3 line may not represent the clinical situation, and little definitive work on the GRP-R status of primary prostate tumors and metastases exists.