Radiolabeled DOTATOC in Patients with Advanced Paraganglioma and Pheochromocytoma

Aim: Paragangliomas and pheochromocytomas are rare tumors arising from chromaffin cells. Approximately 10% are malignant. Treatment options are limited in metastatic, surgically incurable situations. These tumors often express somatostatin receptors in high density. Therefore, treatment with the radiolabeled somatostatin analogue [DOTA-Tyr(3)]-octreotide (DOTATOC) is an option. We evaluated the effectiveness and toxicity of radiolabeled DOTATOC in patients with metastatic paraganglioma and pheochromocytoma.

Methods: Twenty-eight patients (16 female and 12 male) with surgically incurable paragangliomas and pheochromocytomas were included. Twenty-five patients were scheduled for treatment with a total of 200 mCi/m(2) body surface [(90)Y]DOTATOC and 3 for one cycle with 100 mCi/m(2) [(90)Y]DOTATOC followed by 2 cycles of 200 mCi [(177)Lu]DOTATOC. Restaging was performed 8-12 weeks after the last treatment cycle, followed by regular controls every 3 to 6 months.

Results: The treatment was well tolerated. At restaging we found 2 partial remissions, 5 minor responses; 13 stable disease, 2 mixed responses and 6 patients remained progressive. We found 1 thrombocytopenia grade I and 1 anemia grade I. No non-hematological toxicity, especially no kidney toxicity occurred. The follow-up ranged from 6 to 50 months (mean: 19+/-14.6 months). Time to progression ranged from 3 to >42 months. Ten responses, 9 stable diseases and one partial remission, are still ongoing.

Conclusions: In these 28 patients, it was shown that radiolabeled DOTATOC can be effective in patients with somatostatin receptor positive paraganglioma. However, the therapy seems to be less effective than in gastroentero-pancreatic neuroendocrine tumors. Nevertheless, DOTATOC appears to be a treatment option for surgically incurable paragangliomas, because toxicity is very low and especially the fact that long lasting remissions could be achieved justifies the treatment. The final time to progression is not yet reached after a mean follow-up time of 19 months.