Background and importance Three years ago, posology of nivolumab 3 mg/kg was modified in the Summary of Product Characteristics (SmPC) for a fixed dose (flat-dose) of 240 mg every 2 weeks or 480 mg every 4 weeks after showing equivalence.

Aim and objectives The aim of the study was to assess the potential cost savings if we used individualised dose by weight (3 mg/kg) and apply flat-dose (240 mg or 480 mg) in those patients weighing 80 kg or more.

Material and methods Retrospective study conducted in a second-level general hospital that included all patients treated with nivolumab during 1 year (2020).

A database was designed with the following variables: age, sex, weight, diagnosis, dosage regimen and drug costs expressed in laboratory sale price.

After applying the cost optimisation plan, the dosage of the patients was grouped according to weight: ≥80 kg use of flat-dose and <80 kg use of individualised dose of 3 mg/kg.

Costs of administering nivolumab according to an individualised dose of 3 mg/kg and the flat-dose regimen were calculated.

Results During the study period, 37 patients were treated with nivolumab, 29 received a fixed dose of 240 mg every 2 weeks and eight fixed doses of 480 mg monthly. Patients’ mean weight was 71.1 kg (range 52–119). Drug’s total cost was €1 258 560 per year.

Applying the individualised dose of 3 mg/kg in all patients, the cost would be reduced to €1 177 620, generating a saving of €80 940.

Applying the individualised dose of 3 mg/kg and scheduling treatment administration on a single day a week, the cost would be €1 116 558.75, obtaining a saving of €142 002.

In addition to the above measures, setting the dose at 240 mg in those patients weighing ≥80 kg, the cost would be reduced to €1 090 096.50, generating a saving of €168 463.50. Applying this method, based on body weight, only six patients would maintain flat-dose while 31 would require an individualised dose.

Conclusion and relevance The use of individualised nivolumab doses may be a good strategy for optimising treatment costs. The combined use of flat-dose with individualised dose based on patients’ weight would reduce the cost associated with nivolumab by 13.4%, corresponding to about €168 000 per year.

Conflict of interest No conflict of interest