We read the recently published editorial entitled “‘The same old story’: thoughts on authorised doses of anticancer drugs” in this journal with great interest.1 In particular, we were interested in its observations regarding the use of a flat dose for nivolumab and pembrolizumab. Significant concerns have been raised regarding the cost effectiveness of flat dosing of these agents.1 Multiple analyses have demonstrated the use of a flat dose rather than a weight-based dose for these agents leads to higher doses administered to patients, which in turn leads to higher costs.2–5 It is with this background that we present the results of an investigation of the cost effectiveness of flat-dosing in nivolumab and pembrolizumab at a large Irish oncology centre: Cork University Hospital.
We used pharmacy records to identify all patients who had received flat-dosed pembrolizumab and nivolumab at Cork University Hospital in the period starting 1 January 2018 and ending 20 November 2019. Pharmacy records and online patient records were used to retrieve weights for all patients. We used retrieved weights to calculate a hypothetical weight-based dose for each patient by using 2mg/kg dose for pembrolizumab and 3 mg/kg dose for nivolumab. We also used cost per vial of each agent in 2018 and 2019 to extrapolate a hypothetical cost for each dose of the agents for patients. The cost per vial of agent was obtained from the local hospital pharmacy.
A total of 28 patients were found to have undergone flat dosed pembrolizumab in 2018 and 2019. The mean and median weights for our cohort were 72.3 kg and 71.2 kg, respectively. While the flat dose of pembrolizumab was 200 mg every 3 weeks, the calculated median weight-based dose was 142.5 mg. Only two patients had a dose higher than the 200 mg flat dose. While the cost per flat dose of pembrolizumab was Euro (€) 8086, the median hypothetical weight-based cost per dose was € 5758.5. We calculated that if weight-based dosing were used, it would translate into a total cost saving of € 635,417.5 for the entire cohort receiving pembrolizumab during the period.
Similarly for nivolumab, we found a total of 26 patients who had received nivolumab during the period at our centre. The mean and median weights for our cohort were 70.7 kg and 69.4 kg, respectively. While the flat dose of nivolumab was 240mg every 2 weeks, our median weight-based dose of nivolumab was 208 mg. There were seven patients with weight-based doses higher than the flat dose of 240 mg. We also calculated that while the cost per flat dose was € 3872, the median hypothetical weight-based cost per dose was € 3355. The total potential cost saving for the entire cohort receiving nivolumab from the use of weight-based dosing during the period was calculated as € 104,461.
These results support the observations by Meriggi and Zaniboni regarding the use of flat doses in the case of nivolumab and pembrolizumab. We have shown that the concerns raised elsewhere regarding the use of flat dosing of agents, and the potential for increased doses and costs, are equally valid with regard to oncology services in Ireland. Potentially shifting to a weight-based dosing policy for targeted agents, could thus represent significant cost savings.
Footnotes
Authors’ note: This research has been presented as an oral presentation at the Irish Society of Medical Oncology meeting, Dublin, Ireland, 24–25 January 2020.
Conflict of interest statement: The authors declare that there is no conflict of interest.
Funding: The authors received no financial support for the research, authorship, and/or publication of this article.
ORCID iD: Abdul R Farooq 
https://orcid.org/0000-0001-5433-6245
Contributor Information
Abdul R. Farooq, Department of Medical Oncology, Cork University Hospital, Wilton, Cork, Ireland.
Timothy O’Brien, Department of Medical Oncology, Cork University Hospital, Wilton, Cork, Ireland.
Seamus O’Reilly, Department of Medical Oncology, Cork University Hospital, Wilton, Cork, Ireland.
References
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