Background Blinatumomab (Blincyto) is an antibody bispecific indicated in relapsed or refractory B LAL. A single cycle of treatment of blinatumomab consists of 4 weeks of continuous intravenous infusion at a dose of 9 µg/day for the first week and then 28 µg/day followed by a 2 week treatment free interval. The maximums storage time of the infusion is 4 days. Continuous infusion can be given at home with an ambulatory pump. The cost of a 35 µg vial is €2880.

Purpose The objective of this study was to propose optimal organisation to limit the cost of the treatment

Material and methods A simple mathematical calculation was used to evaluate the cost of various possibilities for the administration schedule. Several points were studied: (1) decrease number of bags prepared; (2) optimise the number of vials used; (3) determinate the best administration schedule to reduce changing infusion bag; and (4) avoid changing infusion bag on weekend to reduce costs.

Results (1) Preparation takes account of stability and dose: the first week 2 bags are needed and the following 3 weeks following 6 bags are needed so the minimum number of bags is eight. (2) 651 µg is the efficacy dose for the first cycle, corresponding to 17 vials but the short storage duration of reconstituted vial (24 hours) constrains the use of an additional vial: 18 vials (€51 840). (3) The best schedule for reducing changing the infusion bag must include the 28 µg dose realised in J8 during hospitalisation. (4) Changing infusion bag can be avoided during the weekend if the day of treatment initiation is a Saturday; it will be twice at the weekend if the initiation day is Monday or Thursday.

Conclusion The efficient scheduled for patient care corresponds to 8 preparations with 18 vials. The correct administration schedule is the following: J1, J5, J8, J9, J13, J17, J21, J25. Initiation of treatment should start preferably on a Saturday and avoid as much as possible Monday and Thursday. This practice can be applied in all hospitals and generates the best treatment price.

No conflict of interest