Fluorouracil

The cytotoxicity of the drugs toward the KPC cell line was confirmed by AlamarBlue assay (Supplementary Section S.1, online only). To determine the optimal dose for therapeutic effect and tolerable toxicity, five doses of FOLFIRONOX were injected into mice with heterotopic tumors. The administration of FOLFIRINOX differed from clinical practice as all drugs were administered mixed in one vial as a bolus, whereas clinically the drugs are given sequentially as a 46-h infusion. On the basis of published results with a comparable tumor model [29] , calcium folinate (Pfizer, Zaventem, Belgium), oxaliplatin (SUN Pharma, Hoofddorp, Netherlands), irinotecan (Accord Healthcare, Middlesex, UK) and fluorouracil (Accord Healthcare, Middlesex, UK) were mixed and 100 μL was injected using a 24-gauge lateral tail vain catheter. The doses used are given in Table 1 (doses A-C). Treatment was administered on days 9 and 13 after tumor cell inoculation. All animals were killed 19 d after inoculation. Next, an additional two doses of FOLFIRINOX were injected based on calculations from clinical doses given in established protocols at St. Olav's hospital to equivalent mouse doses using a converting table [30] (doses E and F, Table 1). Treatment was administered on days 9