Efficacy and safety of SOXIRI versus mFOLFIRINOX in advanced pancreatic cancer

BACKGROUND: Modified fluorouracil/leucovorin/irinotecan/oxaliplatin (FOLFIRINOX) regimen (mFOLFIRINOX), comprised of fluorouracil, leucovorin, irinotecan and oxaliplatin, is the first-line standard chemotherapy in patients with advanced pancreatic cancer. The S-1/oxaliplatin/irinotecan (SOXIRI) regimen has also been studied recently under similar conditions. This study compared its efficacy and safety. METHODS: All cases of locally advanced or metastatic pancreatic cancer treated with the SOXIRI or mFOLFIRINOX regimen in Sun Yat-sen University Cancer Centre from July 2012 to June 2021 were reviewed retrospectively. The data of patients who satisfied the inclusion criteria were compared between two cohorts, including overall survival (OS), progression-free survival (PFS), objective response rate, disease control rate and safety. RESULTS: A total of 198 patients were enrolled in the study, including 102 patients treated with SOXIRI and 96 patients treated with mFOLFIRINOX. There was no significant difference in OS [12.1 months versus 11.2 months, hazard ratio (HR) = 1.04, p = 0.81] or PFS (6.5 months versus 6.8 months, HR = 0.99, p = 0.96) between patients treated with SOXIRI and mFOLFIRINOX. In the subgroup analysis, patients with slightly elevated baseline total bilirubin (TBIL) or underweight patients before chemotherapy were more likely to have a longer OS or PFS from SOXIRI than from mFOLFIRINOX. In addition, the carbohydrate antigen (CA)19-9 decline was a good predictor for the efficacy and prognosis of both chemotherapy regimens. All grade adverse events were parallel in all kinds of toxicities except that anaemia was more common in the SOXIRI group than in the mFOLFIRINOX group (41.4% versus 24%, p = 0.03). The occurrence of any grade 3 to 4 toxicity was similar in the two groups. CONCLUSIONS: For locally advanced or metastatic pancreatic cancer patients, the SOXIRI regimen had similar efficacy and controllable safety compared with the mFOLFIRINOX regimen.