Abstract Background Combination therapy with oxaliplatin, irinotecan, fluorouracil, and leucovorin (FOLFIRINOX) chemotherapy drastically improves survival of advanced pancreatic cancer patients. However, the efficacy of FOLFIRINOX as a second-line treatment after gemcitabine failure has not been tested prospectively. We investigated the feasibility and safety of attenuated FOLFIRINOX in patients with gemcitabine-refractory advanced pancreatic cancer. Methods A multicenter phase II prospective open-label, single-arm study was conducted at 14 hospitals. Patients with histologically proven invasive ductal pancreatic adenocarcinoma, a measurable or evaluable lesion, Eastern Cooperative Oncology Group performance status 0 or 1, adequate organ function, and aged 19 years or older were eligible. Attenuated FOLFIRINOX consisted of oxaliplatin 65 mg/m2, irinotecan 135 mg/m2, and leucovorin 400 mg/m2 injected intravenously on day 1 and 5-fluorouracil 2000 mg/m2 continuously infused intravenously over 46 h on days 1–2, repeated every 2 weeks. The primary endpoint was progression-free survival from the initiation of FOLFIRINOX. Secondary endpoints were the objective response rate, disease control rate, overall survival, safety, and tolerability. We estimated overall survival and progression-free survival using the Kaplan–Meier methods. Results We enrolled 39 patients from 14 institutions. The objective response rate was 10.3%, while the disease control rate was 64.1%. The 6-month and 1-year overall survival rates were 59.0% and 15.4%, respectively. Median progression-free survival and overall survival were 3.8 months (95% confidence interval [CI] 1.5–6.0 months) and 8.5 months (95% CI 5.6–11.4 months), respectively. Grade 3 or 4 adverse events were neutropenia (41.0%), nausea (10.3%), anorexia (10.3%), anemia (7.7%), mucositis (7.7%), pneumonia/pleural effusion (5.1%), and fatigue (5.1%). One treatment-related death attributable to septic shock occurred. Conclusion Attenuated FOLFIRINOX may be promising as a second-line therapy for gemcitabine-refractory pancreatic cancer.
