Preclinical study of a new 177Lu-labeled somatostatin receptor antagonist in HT-29 human colorectal cancer cells

Document Type : Original Article


1 Department of Nuclear Pharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran

2 Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran

3 Research Center for Nuclear Medicine, Tehran University of Medical Sciences, Tehran, Iran

4 Department of Toxicology and Pharmacology, Faculty of Pharmacy, Toxicology and Poisoning Research Centre, Tehran

5 Toxicology and Poisoning Research Centre, Tehran University of Medical Sciences, Tehran, Iran

6 Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran

7 Drug Design and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran


Objective(s): Somatostatin receptor-positive neuroendocrine tumors have been targeted using various peptide analogs radiolabeled with therapeutic radionuclides for years. The better biomedical properties of radioantagonists as higher tumor uptake make these radioligands more attractive than agonists for somatostatin receptor-targeted radionuclide therapy. In this study, we tried to evaluate the efficiency of Luthetium-177 (177Lu) radiolabeled DOTA-Peptide 2 (177Lu-DOTA-Peptide 2) as a new radioantagonist in HT-29 human colorectal cancer in vitro and in vivo.
Methods: DOTA conjugated antagonistic peptide with the sequence of p-Cl-Phe-Cyclo(D-Cys-L-BzThi-D-Aph-Lys-Thr-Cys)-D-Tyr-NH2 (DOTA-Peptide 2) was labeled with 177Lu. In vitro assays (saturation binding assay and internalization test) and animal biodistribution were performed in human colon adenocarcinoma cells (HT-29) and HT-29 tumor-bearing nude mice.
Results: 177Lu-DOTA-Peptide 2 showed high stability in acetate buffer and human plasma (>97%). Antagonistic property of 177Lu-DOTA-Peptide 2 was confirmed by low internalization in HT-29 cells (<5%). The desired dissociation constant (Kd =11.14 nM) and effective tumor uptake (10.89 percentage of injected dose per gram of tumor) showed high binding affinity of 177Lu-DOTA-Peptide 2 to somatostatin receptors. 
Conclusion: 177Lu-DOTA-Peptide 2 demonstrated selective and high binding affinity to somatostatin receptors overexpressed on the surface of HT-29 cancer cells, which could make this radiopeptide suitable for somatostatin receptor-targeted radionuclide therapy.


1. Yeong C-H, Ng K-H, Cheng M. Therapeutic radionuclides in nuclear medicine: Current and future prospects. J Zhejiang Univ Sci B. 2014; 15(10):845–63 .
2. Banerjee S, Pillai MRA, Knapp FF. Lutetium- 177 therapeutic radiopharmaceuticals: Linking chemistry, radiochemistry, and practical applications. Chem Rev. 2015; 115(8):2934–74 .
3. Dash A, Chakraborty S, Pillai MRA, Knapp FF (Russ). Peptide receptor radionuclide therapy: An overview. Cancer Biother Radiopharm. 2015; 30(2):47–71 .
4. Bison SM, Konijnenberg MW, Melis M, Pool SE, Bernsen MR, Teunissen JJM, et al. Peptide receptor radionuclide therapy using radiolabeled somatostatin analogs: Focus on future developments. Clin Transl Imaging. 2014; 2(1):55–66 .
5. Fani M, Maecke HR, Okarvi SM. Radiolabeled peptides: Valuable tools for the detection and treatment of cancer. Theranostics. 2012; 2(5):481–501 .
6. Reubi JC. Peptide receptors as molecular targets for cancer diagnosis and therapy. Endocr Rev. 2003; 24(4):389–427 .
7. Stott Reynolds T, P. Bandari R, Jiang Z, J. Smith C. Lutetium-177 labeled bombesin peptides for radionuclide therapy. Curr Radiopharm. 2015; 9(1):33–43 .
8. Rahbar K, Afshar-Oromieh A, Jadvar H, Ahmadzadehfar H. PSMA theranostics: Current status and future directions. Mol Imaging. 2018; 17:1–9 .
9. De Araújo EB, Pujatti PB, Mengatti J. Radiolabeling of substance P with lutetium- 177 And biodistribution study in rat pancreatic tumor xenografted NUDE mice. Cell Mol Biol. 2010; 56(2):12–7 .
10. Cho EH, Lim JC, Lee SY, Jung SH. An assessment tumor targeting ability of 177Lu labeled cyclic CCK analogue peptide by binding with cholecystokinin receptor. J Pharmacol Sci. 2016; 131(3):209–14 .
11. Miao Y, Shelton T, Quinn TP. Therapeutic efficacy of a 177Lu-labeled DOTA conjugated α- melanocyte-stimulating hormone peptide in a murine melanoma-bearing mouse model. Cancer Biother Radiopharm. 2009; 22(3):333–41 .
12. Barbieri F, Bajetto A, Pattarozzi A, Gatti M, Würth R, Thellung S, et al. Peptide receptor targeting in cancer: The somatostatin paradigm. Int J Pept. 2013; 2013:1-20
13. Fani M, Nicolas GP, Wild D. Somatostatin receptor antagonists for imaging and therapy. J Nucl Med. 2017; 58:61S–66S .
14. Behnammanesh H, Jokar S, Erfani M, Geramifar P, Sabzevari O, Amini M, et al. Design, preparation and biological evaluation of a 177Lu-labeled somatostatin receptor antagonist for targeted therapy of neuroendocrine tumors. Bioorg Chem. 2019; doi:10.1016/j.bioorg.2019.103381.
15. Colucci R, Blandizzi C, Ghisu N, Florio T, Del Tacca M. Somatostatin inhibits colon cancer cell growth through cyclooxygenase-2 downregulation. Br J Pharmacol. 2008; 155(2):198–209 .
16. Rylova SN, Stoykow C, Del Pozzo L, Abiraj K, Tamma ML, Kiefer Y, et al. The somatostatin receptor 2 antagonist 64Cu-NODAGA-JR11 outperforms 64Cu-DOTA-TATE in a mouse xenograft model. PLoS One. 2018; 13(4):1–16 .
17. Wadas TJ, Eiblmaier M, Zheleznyak A, Sherman CD, Ferdani R, Liang K, et al. Preparation and biological evaluation of 64Cu-CB-TE2A-sst2-ANT, a somatostatin antagonist for PET imaging of somatostatin receptor-positive tumors. J Nucl Med. 2008; 49(11):1819–27 .
18. de Araújo EB, Caldeira Filho JS, Nagamati LT, Muramoto E, Colturato MT, Couto RM, et al. A comparative study of 131I and 177Lu labeled somatostatin analogues for therapy of neuroendocrine tumours. Appl Radiat Isot. 2009; 67(2):227–33.
19. Kostenich G, Oron-Herman M, Kimel S, Livnah N, Tsarfaty I, Orenstein A. Diagnostic targeting of colon cancer using a novel fluorescent somatostatin conjugate in a mouse xenograft model. Int J Cancer. 2008; 122(9):2044–9 .
20. Liu F, Zhu H, Yu J, Han X, Xie Q, Liu T, et al. 68Ga/177Lu-labeled DOTA-TATE shows similar imaging and biodistribution in neuroendocrine tumor model. Tumor Biol. 2017; 39(6):1-9 .
21. Mikołajczak R, Maecke HR. Radiopharmaceuticals for somatostatin receptor imaging. Nucl Med Rev. 2016; 19(2):126–32 .
22. Bodei L, Kwekkeboom DJ, Kidd M, Modlin IM, Krenning EP. Radiolabeled somatostatin analogue therapy of gastroenteropancreatic cancer. Semin Nucl Med. 2016; 46(3):225–38 .
23. Fani M, Peitl P, Velikyan I. Current status of radiopharmaceuticals for the theranostics of neuroendocrine neoplasms. Pharmaceuticals. 2017; 10(30):1–22 .
24. Price EW, Orvig C. Matching chelators to radiometals for radiopharmaceuticals. Chemical Society Reviews. 2014;43(1):260-90 .
25. Ayiomamitis GD, Notas G, Zaravinos A, Drygiannakis I, Georgiadou M, Sfakianaki O, et al. Effects of octreotide and insulin on colon cancer cellular proliferation and correlation with hTERT activity. Oncoscience. 2014; 1(6):457–467 .
26. Modarai SR, Opdenaker LM, Viswanathan V, Fields JZ, Boman BM. Somatostatin signaling via SSTR1 contributes to the quiescence of colon cancer stem cells. BMC Cancer. 2016; 16(1):1–12 .
27. Wang X, Fani M, Schulz S, Rivier J, Reubi JC, Maecke HR. Comprehensive evaluation of a somatostatin-based radiolabelled antagonist for diagnostic imaging and radionuclide therapy. Eur J Nucl Med Mol Imaging. 2012; 39(12):1876–85 .
28. Cescato R, Waser B, Fani M, Reubi JC. Evaluation of 177Lu-DOTA-sst2 antagonist versus 177Lu-DOTA-sst2 agonist binding in human cancers in vitro. Journal of nuclear medicine. 2011 Dec 1; 52(12):1886-90.
29. Dalm SU, Nonnekens J, Doeswijk GN, de Blois E, van Gent DC, Konijnenberg MW, de Jong M. Comparison of the therapeutic response to treatment with a 177Lu-labeled somatostatin receptor agonist and antagonist in preclinical models. Journal of Nuclear Medicine. 2016 Feb 1; 57(2):260-5.
30. Fani M, Del Pozzo L, Abiraj K, Mansi R, Tamma ML, Cescato R, et al. PET of somatostatin receptor-positive tumors using 64Cu- and 68Ga-somatostatin antagonists: The chelate makes the difference. J Nucl Med. 2011; 52(7):1110–8 .
31. Nicolas GP, Mansi R, McDougall L, Kaufmann J, Bouterfa H, Wild D, et al. Biodistribution, pharmacokinetics, and dosimetry of 177Lu-, 90Y-, and 111In-labeled somatostatin receptor antagonist OPS201 in comparison to the agonist 177Lu-DOTATATE: The mass effect. J Nucl Med. 2017; 58(9):1435–41.
32. Wild D, Fani M, Fischer R, Del Pozzo L, Kaul F, Krebs S, Rivier JE, Reubi JC, Maecke HR, Weber WA. Comparison of somatostatin receptor agonist and antagonist for peptide receptor radionuclide therapy: a pilot study. Journal of nuclear medicine. 2014; 55(8):1248-52.