Treatment of metastatic carcinoids and other neuroendocrine tumors with recombinant interferon‐alpha‐2a: A study by the Italian trials in Medical Oncology Group

Background. Using a wide range of interferon (IFN) doses and schedules, a number of authors have found them to be active against neuroendocrine tumors. Methods. To verify the clinical activity of IFN, 49 evaluable patients with advanced stage low- and intermediate-grade neuroendocrine tumors were treated with recombinant IFN-alpha-2a at a daily dose of 6 × 106 IU intramuscularly for 8 weeks, and 3 times weekly thereafter. The predominant histotype was carcinoid, although a few cases had malignant islet cell tumors, medullary thyroid carcinoma, Merkel cell carcinoma, or other neuroendocrine tumors. All of the patients had measurable lesions and most had multiple sites. Carcinoid syndrome was present in 14 cases. Results. After a median treatment duration of 6 months, complete regression was achieved in 1 of the 7 cases of medullary thyroid carcinoma, and partial response was observed in 4 of 34 carcinoids. Response duration ranged from 1–11 months. Control of the syndrome was obtained in nine patients and a greater than or equal to 50% reduction of 5-hydroxyindoleacetic acid in eight patients. The treatment was well-tolerated. The most frequently observed side effects were fever, flu-like syndrome, and leukopenia. After 12 months of recombinant IFN-alpha-2a, 15 cases in progression and 4 with stable disease or partial response received another treatment (either radiometabolic therapy with I131 metaiodobenzylguanidine or polychemotherapy with streptozotocin plus epirubicin). Conclusions. The use of recombinant IFN-alpha-2a at these doses is well-tolerated and effective in controlling carcinoid syndrome (complete remission plus partial remission, 64%), although it has limited activity on tumor growth inhibition. No definitive data can be given for the other protocol treatments.