Evaluating the Clinical Effectiveness of ⁹⁰Y-SMT 487 in Patients with Neuroendocrine Tumors

Abstract

Because of the presence of cell membrane somatostatin receptors (SSTRs), many neuroendocrine tumors will bind analogs of somatostatin. ⁹⁰Y-Dodecanetetraacetic acid-Phe1-Tyr3-octreotide (SMT 487) is an SSTR radiopharmaceutical currently under investigation as a therapeutic option for neuroendocrine tumors. Although there are a variety of methods for evaluating response to a given cancer therapy, an important indicator of success is the impact on the clinical status of the patient. The purpose of this work was to develop a semiquantitative method and assess the clinical effectiveness of ⁹⁰Y-SMT 487 therapy in patients with neuroendocrine tumors. Methods: A scoring system was developed to evaluate clinical response that included the following parameters: weight, health status score (determined by the patient), Karnofsky score, and tumor-related symptoms. Results: We applied this scoring system to 21 patients who had completed 3 cycles of therapy with ⁹⁰Y-SMT 487. Fourteen of the 21 showed a favorable clinical response, whereas 5 were clinically stable after treatment and 2 showed evidence of clinical progression. There was also a significant reduction in the amount of octreotide being used after completion of ⁹⁰Y-SMT 487 therapy in the 20 patients who were on this medication. Conclusion: Using this scoring method, ⁹⁰Y-SMT 487 appears effective in improving the clinical status of patients with ¹¹¹In-pentetreotide-positive neuroendocrine tumors.