Alternative trastuzumab dosing schedules and association with health care greenhouse gas emissions.

e13644 Background: Climate change due to greenhouse gas (GHG) emissions by humans imperils health. Health care is a major source of GHG emissions and thus reducing health care’s environmental impact should be a global priority. GHG emissions associated with the production and administration of cancer drugs, as well the downstream societal costs in human health terms, are undescribed. The extent to which a given cancer drug’s dosing frequency and duration impact GHG emissions is unknown. Methods: Using trastuzumab for HER2-positive breast cancer as a use case, we conducted a case-control simulation study of single, U.S. academic medical center data to estimate the expected reductions in GHG emissions with three alternative dosing strategies (6-month adjuvant treatment duration, extended-interval dosing, and both) using streamlined life-cycle analysis. We estimated the per-patient relative reduction in GHG emissions expected to occur with each of the alternative dosing strategies and, in exploratory analysis, the societal health costs ( e.g., disability-adjusted life-years [DALYs] and excess mortality per kg CO 2 ) associated with therapy-related GHG emissions, using conventional versus alternative dosing strategies. Results: Adoption of 6-month adjuvant trastuzumab reduced expected per-patient GHG emissions in the adjuvant setting by 10%. Adoption of both 6-month adjuvant trastuzumab and pharmacokinetically-supported every 4-week trastuzumab dosing reduced GHG emissions by 4.5%, 18.7%, and 14.6% in the neoadjuvant, adjuvant, and metastatic settings, respectively. An estimated 8.1 DALYs and 4.6 excess lives are lost annually worldwide as a result of U.S.-based administration of conventionally dosed trastuzumab. Adoption of alternative dosing in the U.S. is estimated to enable avoidance of approximately 1.5 DALYs and 0.9 excess lives lost annually. Conclusions: Alternative dosing strategies, suggested to be noninferior by pharmacokinetic and clinical evidence, are estimated to reduce the societal health costs imposed on bystanders that arise from cancer care’s environmental impact. Environmental impact and its resultant societal health costs should be considered in clinical trial design, re-interpretation of previously conducted trials, regulatory decision-making, and health technology assessments of both new and existing cancer therapies.