Efficacy and safety of capecitabine-temozolomide (CAPTEM) regimen in patients with neuroendocrine neoplasms – experience from NETwerk, a Belgian ENETS Center of Excellence

Neuroendocrine neoplasms (NEN) are rare tumors originating from neuroendocrine cells, commonly found in the gastrointestinal tract and the pulmonary tract. Metastatic well-differentiated neuroendocrine tumors (NET) grade 3 present unique challenges, as they are positioned between the more indolent NET grade 1-2 and the aggressive neuroendocrine carcinomas (NEC). Due to the scarcity of data regarding the optimal systemic treatment for metastatic NET grade 3 and aggressive NET grade 2 subtypes, guidelines remain inconclusive. This retrospective study analyzed data from the NETwerk database, encompassing patients treated with the capecitabine-temozolomide (CAPTEM) regimen between June 2016 and January 2024. The cohort included patients with NET grades 1-3 and NEC. The study focused on assessing the efficacy and safety of CAPTEM. In total, data from 36 patients was analyzed. The median progression-free survival (mPFS) was 13 months, and median overall survival (mOS) was 17 months. Overall response rate (ORR) was 25.8%, and the disease control rate (DCR) was 67.7%. NET grade 2 patients had the highest mPFS, while NET grade 3 exhibited the most favorable mOS. Subgroup analysis showed that panNEN had superior mPFS and mOS compared to other primary tumor sites, with significant differences in mOS based on NEN type. Safety analysis in 20 patients indicated good tolerance and safety. CAPTEM is an efficient and safe regimen for metastatic NEN, with promising outcomes in NET grade 2-3 patients. The promising findings pave the way for further exploration into various aspects of CAPTEM, to better define its position in the therapeutic landscape of NEN.