Activity and Safety of Standard and Prolonged Capecitabine/Temozolomide Administration in Patients with Advanced Neuroendocrine Neoplasms

Background: Capecitabine and temozolomide combination (CAPTEM) is associated with high response rates in patients with advanced neuroendocrine neoplasms (NENs). We evaluated the real-world activity and safety of CAPTEM from 3 NEN centers.

Methods: Clinicopathological characteristics and outcomes of patients treated with CAPTEM for bulky or progressive disease (PD) were retrospectively analyzed. -Results: Seventy-nine patients with gastroenteropancreatic (grades 1-2 [n = 38], grade 3 [n = 24]) and lung/thymic (n = 17) NENs were included. Median treatment duration was 12.1 months (range 0.6-55.6). Overall, partial responses (PRs) occurred in 23 (29.1%), stable (SD) in 24 (30.4%), and PD in 28 (35.4%) patients. Median progression-free survival (PFS) and overall survival (OS) were 10.1 (6-14.2) and 102.9 months (43.3-162.5), respectively. On univariate analysis, NENs naive to chemotherapy and low Ki67 were associated with favorable responses (partial response [PR] + SD; p = 0.011 and 0.045), PFS (p < 0.0001 and 0.002) and OS (p = 0.005 and 0.001). Primary site (pancreas and lung/thymus) was also a significant prognostic factor for PFS (p < 0.0001) and OS (p < 0.0001). On multivariate analysis, gastrointestinal and unknown primary NENs (hazard ratio [HR] 0.3, 95% CI 0.1-0.8, p = 0.009 and p = 0.018) and prior surgery (HR 2.4, 95% CI 11-4.9, p = 0.021) were independent prognostic factors for PFS. Ki-67 was a poor predictor for favorable response in receiver operating characteristic analysis (area under the curve 0.678). Safety analysis of CAPTEM indicated rare events of serious (grades 3-4) toxicities (n = 4) and low discontinuation rates (n = 8) even in patients with prolonged administration (>12 months).

Conclusions: CAPTEM treatment can be an effective and safe treatment even after prolonged administration for patients with NENs of various sites and Ki67 labeling index, associated with significant favorable responses and PFS.