super(90)Y-DOTA-D-Phe super(1)-Try super(3)-Octreotide in Therapy of Neuroendocrine Malignancies

Somatostatin receptors type 2 (sst sub(2)) are expressed in high concentration on numerous neudoendocrine tumors. The successful use of radiolabeled somatostatin analogs in imaging promoted further studies in utilizing them in radiopeptide therapy. The somatostatin analog [ super(90)Y-DOTA-D-Phe super(1)-Try3]octreotide (DOTATOC) (DOTA: 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid) possesses favorable characteristic for its therapeutic use; shows high affinity for sst sub(2), moderately high affinity for sst sub(5), and intermediate affinity for sst sub(3); high hydrophilicity; stable and facile labeling with super(111)In and super(90)Y. In this article we report our experience with super(90)Y-DOTATOC in neuroendocrine tumors. Eighty-seven patients with neuroendocrine tumors were treated with a cumulated activity ranging from 7.4 to 20.2 GBq. Most patients responded with stabilization of disease (48%); however, objective responses were observed in 28% of patients (5% complete response). No major acute reactions were observed up to the activity of 5.55 GBq per cycle. The dose limiting was bone marrow toxicity and the maximal tolerated dose was defined as 5.18 GBq.