Tumors

Regular therapy with the radiolabeled somatostatin analog 177Lu-octreotate (22.2–29.6 GBq) in patients with gastroentero-pancreatic or bronchial neuroendocrine tumors results in tumor remission in 46 % of patients, including minor response. We pres-ent the effects of additional therapy with 177Lu-octreotate in pa-tients in whom progressive disease developed after an initial benefit from regular therapy. Methods: Thirty-three patients with progressive disease after an initial radiologic or clinical re-sponse were treated with additional cycles of 177Lu-octreotate. The intended cumulative dose of additional therapy was 14.8 GBq in 2 cycles. Responses were evaluated using Southwest Oncology Group criteria, including minor response (tumor size reduction of $25 % and,50%). Results: Median time to pro-gression (TTP) after regular therapy was 27 mo. In 4 patients, the intended cumulative dose was not achieved (2 had progres-sive disease, 2 had long-lasting thrombocytopenia). Hemato-logic toxicity grade 3 was observed in 4 patients, and grade 4, in 1. The median follow-up time was 16 mo (range, 1–40 mo). No kidney failure or myelodysplastic syndrome was observed. Renewed tumor regression was observed in 8 patients (2 partial remission, 6 minor response), and 8 patients had stable disease. Median TTP was 17 mo. Treatment outcome was less favorable in patients with a short TTP after regular cycles. Treatment ef-fects in patients with pancreatic neuroendocrine tumors were similar to those in patients with other gastroenteropancreatic neuroendocrine tumors. Conclusion: Most patients tolerated additional cycles with 177Lu-octreotate well. None developed se-rious delayed adverse events. Additional cycles with 177Lu-octreotate can have antitumor effects, but effects were less than for the regular cycles. This may be because of a worse clin-ical condition, more extensive tumor burden, or changed tumor characteristics. We conclude that this salvage therapy can be ef-fective and is safe