SSTR-Mediated Imaging in Breast Cancer: Is There a Role for Radiolabeled Somatostatin Receptor Antagonists?

• DOI: 10.2967/jnumed.116.189035
• Publication Date: 2017-04-28T01:00:29Z
• Authors: Simone U. Dalm; Joost Haeck; Gabriela N. Doeswijk; Erik de Blois; Marion de Jong; Carolien H.M. van...
• Keywords: Biodistribution; Immunostaining

Recent studies have shown enhanced tumor targeting by novel somatostatin receptor (SSTR) antagonists compared with clinically widely used agonists. However, these results been obtained mostly in neuroendocrine tumors, and only limited data are available for cancer types lower SSTR expression, including breast (BC). To date, two reported higher binding of the antagonist than agonist BC, but both a number cases were evaluated. In this preclinical study, we further investigated whether application an can improve SSTR-mediated BC imaging large panel specimens. We also generated vivo mouse model performed SPECT/MRI biodistribution studies. Methods: Binding 111In-DOTA-Tyr3-octreotate (SSTR agonist) 111In-DOTA-JR11 antagonist) to 40 human specimens was using vitro autoradiography. SSTR2 immunostaining confirm expression cells. Furthermore, radiolabeled analyzed tissue material from 6 patient-derived xenografts. One xenograft, estrogen receptor-positive T126, chosen generate models containing orthotopic tumors after injection 177Lu-DOTA-Tyr3-octreotate or 177Lu-DOTA-JR11. Results:111In-DOTA-JR11 significantly (P < 0.001). The median ratio versus 3.39 (interquartile range, 2-5). confirmed on found better visualization antagonist. This result line uptake as measured 285 min radiotracer (percentage injected dose per gram tissue: 1.92 ± 0.43 vs. 0.90 0.17; P = 0.002). Conclusion: promising candidates imaging.