A radioconjugate consisting of the tyrosine-containing somatostatin analog Tyr3-octreotate (TATE) conjugated with the bifunctional chelator 5-(8-methyl-3,6,10,13,16,19-hexaaza-bicyclo[6.6.6]icosan-1-ylamino)-5-oxopentanoic acid (MeCOSar) and radiolabeled with the beta-emitting radioisotope copper Cu 67, with potential antineoplastic activity. Upon administration, copper Cu 67 Tyr3-octreotate binds to somatostatin receptors (SSTRs), with high affinity to type 2 SSTR, present on the cell membranes of many types of neuroendocrine tumor (NET) cells. Upon binding and internalization, this radioconjugate specifically delivers a cytotoxic dose of beta radiation to SSTR-positive cells. TATE is an octreotide derivative in which phenylalanine at position 3 is substituted by tyrosine and position 8 threoninol is replaced with threonine. SSTRs have been shown to be present in large numbers on NET and their metastases, while most other normal tissues express low levels of SSTRs.