4CPS-087 Optimisation of resources in the use of immunotherapy: nivolumab and pembrolizumab weight based dosing instead of flat dose

Background and importanceNivolumab and pembrolizumab are highly selective blockers of anti-programmed death-1 (PD-1). Nivolumab was authorised to be administered in weight based dosing (WBD) schedules at 3 mg/kg every 2 weeks (w) for all indications, and pembrolizumab at 2 mg/kg every 3w in melanoma, urothelial carcinoma, Hodgkin lymphoma and secondline non-small cell lung cancer. In May 2018, the European Commission approved nivolumab 240 mg/2w or 480 mg/4w, and later pembrolizumab 200 mg/2w or 400 mg/8w flat dose (FD) for all indications, replacing WBD with equal efficiency and safety.Aim and objectivesTo describe the economic impact of nivolumab and pembrolizumab WBD instead of FD.Material and methodsAn observational, descriptive and retrospective study was performed in patients treated with nivolumab and pembrolizumab in a reference hospital from May 2018 to September 2019. In agreement with oncology, it was decided to prescribe nivolumab WBD for weight 80 kg, and pembrolizumab WBD for weight 100 kg, for the indications WBD was authorised to improve efficiency. We registered demographic data (sex, weight and age), number of cycles received and doses prescribed in the study period. Patient data were obtained from our chemotherapy prescription and preparation database software and digital clinical history. Direct costs between the use of WBD instead of FD were compared to calculate the economic saving.ResultsSeventy-one patients treated with nivolumab (58) and pembrolizumab (13) were analysed during the study period, 42% men, median age 67.5 (range 43–86) years and median weight 74 kg (range 43–112). A total of 775 cycles of nivolumab and pembrolizumab were administrated and 42/71 patients (59%) were treated with WBD instead of FD because of weight