An Exploratory Study on (99m)Tc-RGD-BBN Peptide Scintimammography in the Assessment of Breast Malignant Lesions Compared to (99m)Tc-3P4-RGD2

PURPOSE: This study aimed to explore the diagnostic performance of single photon emission computed tomography / computerized tomography (SPECT/CT) using a new radiotracer (99m)Tc-RGD-BBN for breast malignant tumor compared with (99m)Tc-3P4-RGD(2). METHODS: 6 female patients with breast malignant tumors diagnosed by fine needle aspiration cytology biopsy (FNAB) who were scheduled to undergo surgery were included in the study. (99m)Tc-3P4-RGD(2) and (99m)Tc-RGD-BBN were performed with single photon emission computed tomography (SPECT) at 1 hour after intravenous injection of 299 ± 30 MBq and 293 ± 32 MBq of radiotracers respectively at separate day. The results were evaluated by the Tumor to non-Tumor ratios (T/NT). (99m)Tc-RGD-BBN and (99m)Tc-3P4-RGD(2) SPECT/CT images were interpreted independently by 3 experienced nuclear medicine physicians using a 3-point scale system. All of the samples were analyzed immunohistochemically to evaluate the integrin αvβ3 and gastrin-releasing peptide receptor (GRPR) expression. The safety, biodistribution and radiation dosimetry of (99m)Tc-RGD-BBN were also evaluated in the healthy volunteers. RESULTS: No serious adverse events were reported in any of the patients during the study. The effective radiation dose entirely conformed to the relevant standards. A total of 6 palpable malignant lesions were detected using (99m)Tc-RGD-BBN SPECT/CT with clear uptake. All malignant lesions were also detected using (99m)Tc-3P4-RGD(2) SPECT/CT. The results showed that five malignant lesions were with clear uptake and the other one with barely an uptake. 4 malignant cases were found with both αvβ3 and GRPR expression, 1 case with only GRPR positive expression (integrin αvβ3 negative) and 1 case with only integrin αvβ3 positive expression (GRPR negative). CONCLUSION: (99m)Tc-RGD-BBN is a safe agent for detecting breast cancer. (99m)Tc-RGD-BBN may have the potential to make up for the deficiency of (99m)Tc-3P4-RGD(2) in the detection of breast cancer with only GRPR positive expression (integrin α(v)β(3) negative). The preliminary application of (99m)Tc-RGD-BBN has demonstrated its powerful potential in breast cancer diagnosis and therapy.