• Joseph Biskupiak, Gary Oderda, Diana Brixner, Derek Tang, Christopher Zacker, and Anand A Dalal.
• 1University of Utah College of Pharmacy, Salt Lake City.
• J Manag Care Spec Pharm. 2019 Aug 1; 25 (8): 859-866.

BackgroundDiscarding unused drugs after dose changes or discontinuation can significantly affect pharmacy budgets. This is especially concerning for expensive oncology agents. However, few economic studies account for drug wastage, providing an inaccurate estimate of a drug's actual economic cost, cost-effectiveness, and value.ObjectivesTo (a) compare the economic impact of drug wastage between ribociclib and palbociclib-clinically similar oral medications for metastatic breast cancer-using 3 approaches (Markov model, pharmacy acquisition cost model, and a retrospective claims analysis) and (b) compare the modeling results with a published estimate of drug wastage for palbociclib from a claims analysis.MethodsA Markov model and a pharmacy acquisitions cost model were developed to evaluate the economic impact of dose reductions for ribociclib and palbociclib over a 1-year time period. Data inputs were pharmacy costs (RED BOOK wholesale acquisition cost) and proportion of patients experiencing dose reductions from either ribociclib randomized clinical trials (MONALEESA-2, -3, or -7) or real-world observational data (Symphony Health retrospective claims analysis). The latter constituted the third approach for quantifying drug wastage. The economic impact of dose reductions for ribociclib and palbociclib in postmenopausal women with previously untreated HR-positive/HER2-negative advanced breast cancer was assessed. Drug wastage was defined as drug doses that could not be used by a patient following a dose reduction. The cost of drug wastage was defined as the cost associated with an unused drug resulting from a dose reduction. The predicted results from the 2 models were compared with a previously published claims analysis that estimated the effect of treatment costs and drug wastage for palbociclib based on the observed dosing patterns from the Symphony Health Solutions database.ResultsIn the Markov model, relative to ribociclib, palbociclib users experienced drug wastage of $112,382 total, or $1,124 per treated patient, per year due to dose changes. In the pharmacy acquisition cost model, relative to ribociclib, palbociclib usage was associated with an increased cost of $7,196 per patient per year (based on a mid-cycle dose reduction) comprising dosing-based cost differences and drug wastage cost for palbociclib of $3,727. The previously published claims analysis found that palbociclib users experiencing a dose reduction had drug wastage costs of $5,471 per patient.ConclusionsIn both models, dose reductions for ribociclib patients resulted in no wastage, since unused tablets could be administered in subsequent cycles, while dose reductions for palbociclib resulted in drug wastage and increased costs. The results from both models were consistent with previously published results from the claims analysis, demonstrating drug wastage costs for palbociclib.DisclosuresThis study received financial support from Novartis Pharmaceuticals, which has products approved for treatment of breast cancer. Tang was employed by Novartis during this study; Zacker and Dalal are employed by Novartis and own company stock. Biskupiak, Brixner, and Oderda received payment from Novartis for this study. Brixner serves as a consultant for Millcreek Outcomes Group and also declares consulting fees from Abbvie, AstraZeneca, Abbott, Becton Dickinson, and Xcenda, unrelated to this study.

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