Somatostatin analogs and prednisone in advanced refractory thymic tumors

BACKGROUND. Therapeutic options to cure advanced, recurrent, and metastatic thymic tumors are limited. Evidence of a high uptake of indium-labeled octreotide (¹¹¹In-DTPA-D-Phe¹-octreotide) in thymic tumors and the curative application of somatostatin analogs and prednisone in one patient with thymoma and pure red cell aplasia led the authors to start a Phase II study. METHODS. Sixteen patients with advanced thymic tumors, unresponsive to conventional chemotherapeutic regimens, were enrolled in the study. The schedule includes administration of somatostatin analog octreotide (1.5 mg/day subcutaneously) associated with prednisone (0.6 mg/kg/day orally for 3 months, 0.2 mg/kg/day orally during follow-up). In 8 cases, octreotide was replaced by the long-acting analog lanreotide (30 mg/every 14 days intramuscolarly). Treatment was prolonged until progression of disease was documented. Overall response rate, survival, progression free survival, and toxicity- were evaluated. RESULTS. The overall response rate among 16 evaluable patients was 37%. One patient (6%) had a complete response, 5 (31%) had a partial response, 6 obtained a stabilization of disease, and 4 progressed during the treatment. After a median follow-up of 43 months, the median survival was 15 months, and median time to progression was 14 months. Treatment was generally well tolerated with acceptable toxicity: cholelithiasis (1 patient), Grade 2 cushingoid appearance (3 patients), Grade 1 diarrhea (5 patients), Grade 2 hyperglycemia (3 patients). CONCLUSIONS. Treatment with somatostatin analogs and prednisone has shown efficacy in patients with recurrent and metastatic malignant thymic tumors refractory to standard therapeutic options. The results obtained are very satisfactory given the lack of effective alternative treatments. Such therapy is not burdened by the same toxicity of chemotherapy; thus, it can be administered to heavily pretreated patients. Somatostatin analogs and prednisone are well tolerated, and the long-acting analog lanreotide, which requires fewer injections, improves patients' compliance.