Peptide receptor radionuclide therapy with 177Lu-DOTATATE for patients with somatostatin receptor-expressing neuroendocrine tumors: the first US phase 2 experience.

OBJECTIVE: Peptide receptor radionuclide therapy with radiolabeled somatostatin analogs is a novel method of treatment in patients with metastatic neuroendocrine tumors (NETs). For the first time in the United States, we present preliminary results of the treatment with Lutetium (177)(Lu) DOTATATE in patients with progressive NETs. METHODS: Thirty-seven patients with grade 1 and grade 2 disseminated and progressive gastroenteropancreatic NET were enrolled in a nonrandomized, phase 2 clinical trial. Repeated cycles of 200 mCi (7.4 GBq; ±10%) were administered up to the cumulative dose of 800 mCi (29.6 GBq; ±10%). RESULTS: Among 32 evaluable patients, partial response and minimal response to treatment were seen in 28% and 3%, respectively, and stable disease was seen in 41% of patients. A total of 28% had progressive disease. A response to treatment was significantly associated with lower burden of disease in the liver. No significant acute or delayed hematologic or kidney toxicity was observed. An impressive improvement of performance status and quality of life were seen after Lu-DOTATATE therapy. CONCLUSIONS: Treatment with multiple cycles of (177)Lu-DOTATATE peptide receptor radionuclide therapy is well tolerated. This treatment results in control of the disease in most patients, whereas systemic toxicities are limited and reversible. Quality of life is also improved.

Long-Term Survival, Toxicity Profile, and role of F-18 FDG PET/CT scan in Patients with Progressive Neuroendocrine Tumors Following Peptide Receptor Radionuclide Therapy with High Activity In-111 Pentetreotide.

AIM: To study the long term benefits, toxicity and survival rate in patients with neuroendocrine tumors receiving multiple cycles of high activity In-111 Pentetreotide therapy. Moreover, our secondary aim was to evaluate the value of F-18 FDG PET-CT scan as prognostic indicator in this group of patients. BACKGROUND: Neuroendocrine tumors are a heterogeneous group of malignancies which are usually metastatic at diagnosis. Standard chemotherapy in these patients is associated with appreciable adverse events and low effectiveness. Since 1990s, Peptide receptor radionuclide therapy (PRRT) with radio-labeled somatostatin analogues has been introduced as a new method of treatment in patients with unresectable and/or metastatic neuroendocrine tumors expressing high levels of Somatostatin receptors. METHODS: 112 patients with progressive disseminated and unresectable neuroendocrine tumor (stage III and stage IV) were enrolled in a non-randomized trial in an out-patient setting. High activity In-111 Pentetreotide (500 mCi (18.5 GBq) per cycle) was administered as an intravenous infusion over 3 hours and repeated therapy cycles every 9-12 weeks in eligible patients up to maximum of 4 cycles. Response to therapy was evaluated by clinical imaging using the RECIST criteria, metabolic criteria and patient's quality of life questionnaire. Dosimetry and biodistribution studies were also performed. Finally, Kaplan-Meier survival analysis was performed for patients followed for greater than 12 months. The relationship between pretreatment F-18 FDG PET-CT scan status and survival was determined by two-tailed Student's t-test in 42 patients who underwent pre-therapy PET scans. RESULTS: For an average of 25 (median 18.65) months following the therapy, patients were evaluated for any evidence of toxicity. No significant acute toxicity was observed in patients. Grade II or III hematological toxicity (7.6% of patients), liver toxicity (18.4%) and also grade I renal toxicity (6.1%) was observed in 92 evaluable patients. Radiological responses were evaluated for an average of 29 months following their last cycle of therapy and results were analyzed by the RECIST criteria. Majority (85%) of patients had stable disease (SD), partial response (PR) rate was 7.5% and progressive disease (PD) was observed in 7.5% of patients. The average survival was 24.67 months after 2 cycles of therapy, 30.53 months after 3 cycles of therapy and 30.19 months after 4 cycles of therapy. Of the 42 patients who had pretreatment PET-CT imaging, 31 patients had positive F-18 FDG scans (SUV > 2.5) with an average survival time of 18.9 months (range 1.4-45.8 months) and 11 patients had negative F-18 FDG scans (SUV ≤ 2.5) with an average survival time of 31.8 months (range 7.4-42.9 months). Survival times for FDG negative patients were significantly longer than those for FDG positive patients (p = 0.001 with 95% confidence). CONCLUSION: High activity In-111 therapy is a safe and effective therapy for patients with progressive disseminated neuroendocrine tumors. No major hematological, renal and hepatic toxicities were observed. There was an increase in survival time particularly in patients with lower degree of liver involvement as well as patients who received three or more cycles of therapy, as compared to historical data. Pre-treatment FDG status may be a predictor of survival following In-111 pentetreotide therapy.

Indium-111-pentetreotide prolongs survival in gastroenteropancreatic malignancies.

Somatostatin and its analogues bind to somatostatin receptors (sst) 1 through 5 that are overexpressed in neuroendocrine neoplasms such as gastroenteropancreatic (GEP) malignancies. After ligand-receptor binding, a fraction of the ligand-receptor complexes internalize. This internalization process is an effective means of delivering cytotoxic radiolabeled somatostatin analogues, especially those emitting short-range decay particles such as Auger electrons, to the neoplastic cell nucleus. Indium-111-pentetreotide, an sst 2 preferring somatostatin analogue with gamma and Auger electron decay characteristics, is commonly used for the scintigraphic evaluation and management of neuroendocrine cancer patients. This clinical trial was performed to determine the effectiveness and tolerability of therapeutic doses of (111)In-pentetreotide in patients with GEP tumors. GEP tumor patients who had failed all forms of conventional therapy, with worsening of tumor-related signs and symptoms and/or radiographically documented progressive disease, an expected survival less than 6 months, and sst positivity as determined by the uptake on a 6.0 mCi (111)In-pentetreotide scan (OctreoScan; Mallinckrodt Medical, Inc, St. Louis, MO), were treated with at least 2 monthly 180-mCi intravenous injections of (111)In-pentetreotide. Baseline clinical assessments, serum chemistries, and plasma pancreastatin levels were measured and repeated before each (111)In-pentetreotide treatment. From February 1997 to February 1998, 27 GEP (24 carcinoid neoplasms with carcinoid syndrome and 3 pancreatic islet cells) patients were accrued, with 26 patients evaluable for clinical and radiographic responses, 21 patients evaluable for biochemical assessments, and 27 patients evaluable for survival analysis and safety. Toxicity was evaluated by using standard National Cancer Institute (NCI) Common Toxicity Criteria guidelines. Clinical benefit occurred in 16 (62%) patients. Pancreastatin levels decreased by 50% or more in 81% of the patients. Objective partial radiographic responses occurred in 2 (8%) patients, and significant tumor necrosis (defined by 20 Hounsfield units or greater decrease from baseline) developed in 7 (27%) patients. The following transient Grades 3/4 NCI Common Toxicity Criteria side effects were observed, respectively: leukocyte: 1/1; platelets: 0/2; hemoglobin: 3/0; bilirubin: 1/3; creatinine: 1/0; neurologic: 1/0. Myeloproliferative disease and/or myelodysplastic syndrome have not been observed in the 6 patients followed-up for 48+ months. The median survival was 18 months (range, 3-54+ mo). Two doses (180 mCi) of (111)In-pentetreotide are safe, well-tolerated, and improve symptoms in 62% of patients, decrease hormonal markers in 81% of patients, decrease Hounsfield units on computed tomography (CT) scans in 27% of patients, with 8% partial radiographic responses and increased expected survival in GEP cancer patients with somatostatin receptor-expressing tumors. The maximal tolerated dose of (111)In-pentetreotide and the optimal dosing schedules remain under investigation.