Economic analysis of alternative pembrolizumab and nivolumab dosing strategies at an academic cancer center.

Abstract

6504 Background: Pembrolizumab (P) and nivolumab (N) were initially investigated and FDA-approved with weight-based dosing strategies, but later the approval label was amended to a fixed dose administration. Given increasing concerns about financial toxicity of cancer therapies, we hypothesize that weight-based dosing of P and N and allowing vial sharing among patients will result in substantial cost savings. Methods: We obtained IRB approval to retrospectively examine all outpatient doses of P and N given at three Stanford Medicine infusion centers between July 1, 2018 and Oct 31, 2018 using the Stanford Medicine Research Data Repository (STARR) database. We performed cost-minimization analysis modeling the impact of dosing strategies based upon patient weight versus fixed dosing (2 mg/kg vs 200 mg q3wks for P; 3 mg/kg vs 240 mg q2wks or 6 mg/kg vs 480 q4wks for N). “Dose-minimization” (DM) was defined as whichever dose was lower (weight-based or fixed dose). The impact of allowing vial sharing (considering commercially available vial sizes) between patients treated at the same site and on the same date was assessed. Average sales price (ASP) from Center for Medicare and Medicaid Services for Part B drugs was used for cost estimates. Results: A total of 1,029 doses of P or N were administered across a variety of cancer types. For most doses (N = 789, 77%), the calculated weight-based dose was less than the fixed dose. DM resulted in decreased usage and expenditures of both P and N, and a further decrease was observed with vial sharing. Total savings estimated with DM and vial sharing strategy were > $1.4 million (Table). This amounted to savings of > 22,000 mg of P (112 fixed doses) and > 11000 mg of N (47 fixed doses). Savings were greatest at the highest volume infusion center. Conclusions: Alternative dosing strategies of P and N would result in significantly less drug utilization and pharmaceutical expenditure without anticipated impact on efficacy. Potential barriers to this approach include existing policies regarding vial sharing and drug vial sizes. [Table: see text]