Development of hematologic toxicity with sequential treatment of Y90 followed by PRRT in five patients at single institution with metastatic neuroendocrine patients.

Abstract

81 Background: In metastatic neuroendocrine tumors (NET) peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogues (Lu-177-DOTATATE) and selective intra-arterial radio-therapy (SIRT) with Y-90-microspheres are increasingly used promising treatment options. Rarely patients have been treated with sequential use of both treatment modalities . Severe adverse effects are rare and mainly concern hematologic changes and development of prolonged cytopenias . There is no data about possible cumulative side effects particularly regarding hematologic toxicity in the case of sequential use of both treatments. Methods: 5 Patients with hepatic metastasized NET treated both with SIRT and PRRT during 2010 - 2019 were included. Average time interval between treatment of y90 and PRRT was 2.5 years. All of them were treated with y90 before PRRT. Average treatment with Y90 was 3 doses. Results: In the follow up Platelets (159 to 89), leukocytes (7.5 to 3.7) and hemoglobin (13 to 11.6 ) decreased significantly, LFTs, bilirubin and creatinine did not change significantly. No severe toxicity (Grade 3 or 4) was experienced. 80 % of the patients showed decreasing blood counts after the therapies and was prolonged for average of 9 months. Conclusions: In metastatic neuroendocrine tumors (NET) sequential treatment with peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogues (Lu-177-DOTATATE) after selective intra-arterial radio-therapy (SIRT) with Y-90-microspheres is possible and well tolerated except for hematological toxicity.