Radiolabeled Somatostatin Analog [¹⁷⁷Lu-DOTA⁰,Tyr³]Octreotate in Patients With Endocrine Gastroenteropancreatic Tumors

<jats:sec><jats:title>Purpose</jats:title><jats:p> There are few treatment options for patients with metastasized or inoperable endocrine gastroenteropancreatic (GEP) tumors. Chemotherapy can be effective, but the response is usually less than 1 year. Here, we present the results of treatment with a radiolabeled somatostatin analog, [<jats:sup>177</jats:sup>Lu-DOTA<jats:sup>0</jats:sup>,Tyr<jats:sup>3</jats:sup>]octreotate (<jats:sup>177</jats:sup>Lu-octreotate). </jats:p></jats:sec><jats:sec><jats:title>Patients and Methods</jats:title><jats:p> One hundred thirty-one patients with somatostatin receptor-positive tumors were treated with up to a cumulative dose of 600 to 800 mCi (22.2 to 29.6 GBq) of <jats:sup>177</jats:sup>Lu-octreotate. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> One patient developed renal insufficiency, and another patient developed hepatorenal syndrome. Creatinine clearance did not change significantly in the other patients. WHO hematologic toxicity grade 3 or 4 occurred after less than 2% of the administrations. We observed complete remission in three patients (2%), partial remission in 32 patients (26%), minor response (tumor diameter decrease of 25% to 50%) in 24 patients (19%), stable disease (SD) in 44 patients (35%), and progressive disease (PD) in 22 patients (18%). Higher remission rates were positively correlated with high uptake on pretherapy somatostatin receptor imaging and a limited number of liver metastases, whereas PD was significantly more frequent in patients with a low performance score and extensive disease. Median time to progression in 103 patients who either had SD or tumor regression was more than 36 months. </jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p> Treatment with <jats:sup>177</jats:sup>Lu-octreotate results in tumor remission in a high percentage of patients with GEP tumors. Serious side effects are rare. The median time to progression compares favorably with chemotherapy. Results are better in patients with a limited tumor load. Therefore, early treatment, even in patients who have no PD, may be better. </jats:p></jats:sec>