Streptozocin/5-fluorouracil Chemotherapy of Pancreatic Neuroendocrine Tumours in the Era of Targeted Therapy

Purpose: The role of streptozocin-based chemotherapy (STZ CTx) in advanced, well-differentiated pancreatic neuroendocrine tumours (PanNET) and the best sequence of treatments in advanced PanNET are unclear. We examined the outcomes after STZ CTx in patients who had been selected according to the current therapeutic guidelines.

Methods: Data from 50 PanNET patients consecutively treated with STZ CTx between 2010 and 2018 were analysed. The endpoints of the study were the objective-response rate (ORR), progression-free survival (PFS), and overall survival (OS).

Results: STZ CTx was the first-line treatment in 54% of patients. The PanNET grades were as follows: 6% G1, 88% G2, and 6% well-differentiated G3. The ORR was 38%. Stable disease was the best response in 38% of patients and 24% showed progressive disease. Treatment was discontinued because of toxicity in one patient. Median PFS and OS were 12 (95% confidence interval (CI), 8.5-15.5) and 38 months (95% CI, 20.4-55.6), respectively. In the Kaplan-Meier analysis, the median OS was 89 months (95% CI, 34.9-143.1) for STZ CTx as first-line therapy compared with 22 months (95% CI, 19.3-24.7; p = 0.001, log-rank test) for subsequent lines. Bone metastases negatively impacted survival (HR, 2.71, p = 0.009, univariate analysis, HR, 2.64, p = 0.015, multivariate analysis, and Cox regression).

Conclusions: In patients selected according to current guidelines, PFS, and OS after STZ CTx were lower than previously reported, whereas ORR was unchanged. First-line treatment was positively associated with OS and the presence of bone metastases was negatively associated with OS. Pre-treatment with targeted or peptide-receptor radionuclide therapy did not alter ORR, PFS, or OS.