Salvage Chemotherapy by FOLFIRI Regimen for Poorly Differentiated Gastrointestinal Neuroendocrine Carcinoma

Chemotherapy is the mainstay treatment for advanced poorly differentiated gastrointestinal neuroendocrine carcinoma (GI-NEC), with platinum-containing regimens being the optimal first-line regimen. However, the role and efficacy of second-line chemotherapy for GI-NEC are unclear. This study aimed to evaluate the feasibility and efficacy of fluorouracil, leucovorin, and irinotecan (FOLFIRI) as second-line therapy in patients with relapsed or recurrent GI-NEC after first-line platinum plus etoposide therapy. We retrospectively evaluated eight consecutive patients with unresectable GI-NEC treated between 2017 and 2020. The inclusion criteria were pre-treatment with platinum doublet therapy, performance status (PS) 0–2, having measurable lesions, and treatment with FOLFIRI as second-line therapy. The overall response rate, progression-free survival (PFS), overall survival (OS), safety, and relative dose intensity were evaluated. Five patients met the inclusion criteria. Overall, 37 cycles of FOLFIRI were administered. The relative dose intensities for irinotecan, continuous infusion of 5-FU, and a bolus injection of 5-FU were 76%, 72%, and 54%, respectively. Overall, 2 of the 5 patients achieved partial response (40%), and the duration of response (DOR) was 4.0 months. The PFS and OS rates were 5.8 (95% CI, 1.5-NA) and 11 (95% CI, 6.3-NA) months, respectively. Overall, 4 of the 5 patients (80%) proceeded with further chemotherapy. Grade ≥ 3 adverse events except hematological toxicity included febrile neutropenia (n = 2), anorexia (n = 2), and fatigue (n = 1). Treatment discontinuation due to treatment-related adverse events was not observed. FOLFIRI showed modest efficacy and feasibility for GI-NEC patients and has thus potential for patients who fail the first-line treatment.