177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in patients with somatostatin-expressing neuroendocrine tumors: A real-world retrospective review of efficacy and safety from an Australian tertiary cancer Center.

Abstract

e16198 Background: There is relatively limited data guiding optimal treatment algorithms for inoperable or metastatic neuroendocrine tumours (NETs). The randomised NETTER 1 study established PRRT as a standard of care in midgut NET. The aim of this study was to retrospectively review the efficacy and safety of patients treated with 177Lu-DOTATATE at Royal Brisbane and Women’s Hospital. Methods: Consecutive patients with unresectable or metastatic NET who received their first 177Lu-DOTATATE therapy between 2010 and 2017 were identified. Paragangliomas were excluded. Response rates, progression free survival (PFS) and overall survival (OS) were assessed via a combination of chart review, post-therapeutic 68Ga DOTATATE PET/CT and multi-disciplinary meeting decisions. Gr3/4 haematological and renal safety data was analysed via chart review. Progression free survival (PFS) and overall survival (OS) were assessed via the Kaplan-Meier method. Results: 123 consecutive patients were included in the analysis (57% male, median age 61). Primary site: 41% gastroenteric, 34% pancreatic, 10% lung, 6% colon/rectum, 9% other. Grade 1 (42%), Grade 2 (31%) Grade 3 (6%), unknown (21%). 76% of patients had previously received somatostatin analogues. 80% received four cycles (with persistent myelosuppression the most common cause of ceasing therapy early). 20% of patients received concurrent chemotherapy (10% capecitabine, 10% capecitabine and temozolomide). For the entire cohort, median follow up was 51 months. Median PFS, 34.2 months (95% CI, 30.3 – 38.17) and median OS, 61 months (95% CI, 54.2– 67.8). There was no significant difference in PFS or OS between small bowel and pancreatic patients. Response rates to PRRT included complete response (n = 4, 3%), stable or responding disease (n = 96, 78%), progressive disease (n = 22, 18%), not assessable (1, 1%). Grade 3 or 4 thrombocytopenia, neutropenia or anaemia occurred in less than 1% of patients. Confirmed acute leukaemia occurred in three patients. One patient had grade 3 renal toxicity secondary to treatment. 26 patients received retreatment with 177Lu-DOTATATE at progression with median time to re-treatment of 35 months. Conclusions: This single centre, retrospective audit confirms the efficacy of 177Lu-DOTATATE in the treatment of unresectable and metastatic NETs. Treatment was associated with low rates of severe haematological or renal adverse events. Our results are comparable to similar published reviews.