The Impact of DDR Gene Mutations on the Efficacy of Etoposide Plus Cisplatin in Grade 3 Metastatic Gastroenteropancreatic (GEP)-Neuroendocrine Carcinoma (NEC).

Purpose: Neuroendocrine carcinomas (NECs) are aggressive tumors treated with cisplatin-based chemotherapy, though responses vary. As DNA damage response (DDR) pathways influence cisplatin sensitivity, this single-center retrospective study evaluates the efficacy of first-line cisplatin in recurrent or metastatic NEC based on DDR mutation status.

Materials And Methods: This study analyzed patients with grade 3 recurrent or metastatic NEC treated with first-line etoposide plus cisplatin at Samsung Medical Center between January 2019 and September 2023. All patients underwent next-generation sequencing to determine DDR mutation status, defined by pathogenic alterations in major DNA repair pathways. Clinical outcomes were assessed per RECIST v1.1. Survival analyses were conducted using Kaplan-Meier methods and Cox regression models, with significance set at ≤ 0.05.

Results: A total of 40 patients with NEC were included in this study. There were 16 patients with DDR wild-type (WT) and 24 patients with DDR mutant type (MT). The most common primary tumor sites were the pancreas (25.0%), stomach (20.0%), and gallbladder/duct (12.5%). Among 40 patients, those with DDR mutations ( = 24) showed significantly higher objective response (58.3% vs. 12.5%) and disease control rates (91.7% vs. 50.0%) compared to patients with DDR WT ( = 16). The median progression-free survival (PFS) showed the favorable trend in the DDR mutant group (8.0 vs. 4.3 months; = 0.15), with similar trends observed across homologous recombination repair (HRR), Fanconi anemia (FA), and mismatch repair (MMR) subgroups.

Conclusions: This study revealed that patients with DDR mutations had significantly higher response to first-line etoposide-cisplatin, suggesting DDR mutation status as a potential predictive marker to guide treatment and improve outcomes in recurrent or metastatic NEC.