DOTA-Lanreotide: A Novel Somatostatin Analog for Tumor Diagnosis and Therapy*

Long acting somatostatin-14 (SST) analogs are used clinically to inhibit tumor growth and proliferation of various tumor types via binding to specific receptors (R). We have developed a 111In-/90Y-labeled SST analog, DOTA-(d)βNal1-lanreotide (DOTALAN), for tumor diagnosis and therapy. 111In-/90Y-DOTALAN bound with high affinity (dissociation constant, Kd, 1–12 nm) to a number of primary human tumors (n = 31) such as intestinal adenocarcinoma (n = 17; 150-4000 fmol/mg protein) or breast cancer (n = 4; 250-9000 fmol/mg protein). 111In-/90Y-DOTALAN exhibited a similar high binding affinity (Kd, 1–15 nm) for the human breast cancer cell lines T47D and ZR75–1, the prostate cancer cell lines PC3 and DU145, the colonic adenocarcinoma cell line HT29, the pancreatic adenocarcinoma cell line PANC1, and the melanoma cell line 518A2. When expressed in COS7 cells, 111In-DOTALAN bound with high affinity to hsst2 (Kd, 4.3 nm), hsst3 (Kd, 5.1 nm), hsst4 (Kd, 3.8 nm), and hsst5 (Kd, 10 nm) and with lower affinity to hsst1...