Background Nivolumab is a monoclonal antibody targeting PD1 approved by the EMA in 2015, and used in non-small cell lung cancer (NSCLC). The industrial development strategy was primarily a weight-based approach with 3 mg/kg every 2 weeks (Q2W). In 2018, the dosing regimen was simplified for a flat dose of 240 mg Q2W, because some studies assessed this strategy as effective and safe.^1–3 One of these studies had shown a non-statistical trend in more serious side effects (SSE) in low bodyweight patients (LBW,<50 kg).²

Purpose To review the new dosing regimen and to evaluate if it would represent significant financial changes for our hospital regarding the patients’ cohort.

Material and methods We retrospectively recorded anthropometric and clinical data from all the patients treated by nivolumab for NSCLC in our centre between January 2017 and June 2018. We evaluated the cost per milligram of nivolumab (thanks to the national reimbursement data). We calculated the cost for three treatment strategies: 3 mg/kg Q2W, 240 mg flat dose Q2W (as if a new dosing strategy was applied along with the treatment) and 240 mg flat dose Q2W except for patients under 50 kg (mixed strategy, 3 mg/kg Q2W dosing regimen, taking into account the trend in more SSE in LBW patients).²

Results A total of 49 patients were included in the study (sex ratio M/F=3.08). The mean age was 67±9 years and mean bodyweight 69.4±19.2 kg (six patients under 50 kg). The nivolumab average cost per milligram in our country was evaluated at €10.57. The costs were €1,411,988 for the 3 mg/kg, €1,608,331 for the flat dose (14% more expensive) and €1,500,024 for the mixed strategy, taking into account low bodyweight patients (8.4% more expensive).

Conclusion Nivolumab flat dose presents practical benefits in terms of prescription and preparation, but also an extra cost regarding our patients’ population in NSCLC. Its prescription should be considered wisely in LBW patients waiting the results of clinical trials. Flat-dose strategies for monoclonal antibodies in oncology are a challenge but also a paradox in the era of personalised medicine.

References and/or acknowledgements 1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5634778/

2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5834087/

3. https://ascpt.onlinelibrary.wiley.com/doi/full/10.1002/cpt.875

No conflict of interest.