Efficacy of capecitabine and temozolomide (CAPTEM) in patients with gastrointestinal neuroendocrine tumors (GI-NETs).

Abstract

637 Background: CAPTEM is a treatment option for patients (pts) with well-differentiated pancreatic NETs based on the phase 2 E2211 trial. Due to limited data in pts with GI-NETs we evaluated the efficacy and safety of CAPTEM in pts with advanced GI-NETs treated at University of Michigan. Methods: This IRB approved retrospective study included 18 years or older consecutive pts with advanced unresectable GI-NET who received CAPTEM between 09/2013 and 09/2024. Pts with poorly differentiated neuroendocrine carcinoma were excluded. Pt characteristics, chemotherapy and related toxicity, and survival data were obtained through review of electronic medical records. The primary and secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety based on incidence of adverse events. Results: In 45 pts who met criteria, median (range) age was 60.5 (31-83) years, 25 (55.5%) were female, 40 (88.8%) were White and 36 (80.0%) had ECOG 0-1. Most patients had metastatic stage (31, 68.8%) at diagnosis. The primary sites included stomach (2.2%), small bowel (66.6%), colon (11.1%), rectum (6.7%) and unknown primary with suspected intestinal origin (13.3%). Tumors were well-differentiated (68.9%), grade 1 (14, 31.1%), grade 2 (16, 35.5%), grade 3 (6, 13.3%) while rest had missing data. On imaging, somatostatin receptor positivity was reported in 30 (66.7%) pts. CAPTEM was used as 1L therapy in 14 (31.1%), 2L in 18 (20.4%), and 3L in 6 (13.3%) with concurrent somatostatin analogue in 28 (62.2%) pts. Median (95% CI) PFS on CAPTEM was 7.6 (3.2-NR) months (mo) and PFS rate (95% CI) at 1 year was 33% (19-58). Median (95% CI) OS from start of CAPTEM and from diagnosis were 25.6 (15.9-NR) and 50 (34.3-NR) mo, respectively. Toxicity data are pending and will be presented. Conclusions: CAPTEM demonstrated modest efficacy in pts with advanced unresectable GI-NETs thus supporting its use as a reasonable therapeutic option for this subset of NETs.