Capecitabine and temozolomide combination for treatment of high-grade, well-differentiated neuroendocrine tumour and poorly-differentiated neuroendocrine carcinoma - retrospective analysis

Introduction: Many retrospective studies have confirmed that capecitabine combined with temozolomide is effective in neuroendocrine neoplasms. Most of the studies focused on grade 1 and grade 2 neuroendocrine tumours, mainly of pancreatic origin. There are limited data regarding the efficacy capecitabine with temozolomide in grade 3 neuroendocrine tumours. The new World Health Organisation 2017 classification distinguished well-differentiated grade 3 neuroendocrine tumours from poorly differentiated grade 3 neuroendocrine carcinomas. Treatment options for grade 3 neuroendocrine neoplasms are limited, and the overall prognosis is better in the subgroup of patients with grade 3 neuroendocrine tumours. Material and methods: It was a retrospective study in the population of patients with diagnosed grade 3 neuroendocrine neoplasms of different origin treated with capecitabine and temozolomide. Data on clinical and demographic characteristics of the population were collected from four Polish clinical centres. This study aimed to evaluate response and survival parameters and compare outcomes of treatment of neuroendocrine tumours and carcinomas. Results: The study included 32 patients with grade 3 neuroendocrine tumours treated with capedtabine and temozolomide. The disease control rate was twice as high in the group of patient with neuroendocrine tumours in comparison to carcinomas (70 vs. 30%). The progression-free survival for patients with neuroendocrine tumours was 15.3 months (95% CI: 3.9-30.4), and for patients with neuroendocrine carcinomas it was 3.3 months (95% CI: 2.5 7.1). Median overall survival was 22 months (95% CI: 11.812.0) and 4.6 months (95% CI: 2.2-5.9) for patients with tumours and carcinomas, respectively. The treatment regimen was generally well tolerated. Conclusions: The combination of capedtabine and temozolomide is an effective treatment for patients with grade 3 neuroendocrine tumours with Ki-67 index ranging between 20 and 54%. The treatment did not overcome the aggressive character of neuroendocrine carcinomas and resulted in low response and survival outcomes in comparison to those achieved in tumour therapy.