Fixed or weight-adjusted dose in immunotherapy?

Abstract

Objective: To analyse the economic impact of the use of immune checkpoint inhibitors in fixed-dose regimens and to determine the potential economic savings of using weight-adjusted dosing, as well as to describe the current situation in Spanish hospitals.

Methods: Observational, descriptive, retrospective and multicentre study that included all patients treated with pembrolizumab, nivolumab, avelumab, durvalumab and cemiplimab in fixed-dose regimens from 2020 to 2022 in four hospitals in a Spanish province (Albacete). Clinical variables: drug, therapeutic indication, body weight, percentage of overdose and number of cycles received. Economic variables studied included: cost per cycle (fixed-dose and weight-adjusted dosing), total cost and opportunity cost. The dosage regimen chosen for immune checkpoint inhibitors in Spain was carried out by means of an anonymous survey. The survey was sent out using a distribution list of the Oncology Pharmacy Working Group (GEDEFO) of the Spanish Society of Hospital Pharmacy (SEFH).

Results: The study included 297 patients (155 pembrolizumab, 115 nivolumab, 12 avelumab, 11 durvalumab and 4 cemiplimab). The opportunity cost: pembrolizumab €615,316, nivolumab €486,327, avelumab €19,974, durvalumab €28,367 and cemiplimab €4,008. A total of 53 responses to the survey were received. In 54.7% of cases the weight-adjusted dosing regimen had been partially implemented in the prescription of some drugs and/or indications. In those hospitals that used weight-adjusted dosing, the decision was mainly made by the Pharmacy Service in consensus with Oncology (70.5%).

Conclusions: Our study showed a percentage of overdose of all drugs when using a fixed-dose regimen. This translates into a considerable increase in the budgetary impact versus the weight-adjusted dosing. The survey shows the scenario of our healthcare practice at the national level, confirming the variability in dosage regimens used in Spanish hospitals and the possible budgetary impact that therapeutic optimisation would entail.