68Ga-BBN-RGD PET/CT for GRPR and Integrin αvβ3 Imaging in Patients with Breast Cancer

Purpose: This study was to assess a gastrin-releasing peptide receptor (GRPR) and integrin αvβ3 dual targeting tracer 68Ga-BBN-RGD for positron emission tomography (PET)/computed tomography (CT) imaging of breast cancer and metastasis. Materials and Methods: Twenty-two female patients were recruited either with suspected breast cancer on screening mammography (n = 16) or underwent breast cancer radical mastectomy (n = 6). All the 22 patients underwent PET/CT at 30-45 min after intravenous injection of 68Ga-BBN-RGD. Eleven out of 22 patients also accepted 68Ga-BBN PET/CT within 2 weeks for comparison. A final diagnosis was made based on the histopathologic examination of surgical excision or biopsy. Results: Both the primary cancer and metastases showed positive 68Ga-BBN-RGD accumulation. The T/B ratios of 68Ga-BBN-RGD accumulation were 2.10 to 9.44 in primary cancer and 1.10 to 3.71 in axillary lymph node metastasis, 3.80 to 10.7 in distant lymph nodes, 2.70 to 5.35 in lung metastasis and 3.17 to 22.8 in bone metastasis, respectively. For primary lesions, the SUVmax from 68Ga-BBN-RGD PET in ER positive group was higher than that in ER negative group (P < 0.01). For both primary and metastatic lesions, SUVmean quantified from 68Ga-BBN-RGD PET correlated well with both GRPR expression and integrin αvβ3 expression. Conclusion: This study demonstrated significant uptake of a new type of dual integrin αvβ3 and GRPR targeting radiotracer in both the primary lesion and the metastases of breast cancer. 68Ga-BBN-RGD PET/CT may be of great value in discerning both primary breast cancers, axillary lymph node metastasis and distant metastases.