CP-127 Switching from intravenous to subcutaneous formulation of TRASTUZUMAB: costs and safety

Background Trastuzumab containing regimens are the standard of care for HER2+ breast cancer. While intravenous trastuzumab (Tiv) is administered as a weight based dose using an initial 90 min infusion followed by a subsequent 30 min infusion, subcutaneous trastuzumab (Tsc) is administered as a fixed 600 mg dose over 5 min without compromising its efficacy and safety. Potential savings associated with Tsc include loading dose avoidance and time reductions related to preparation and administration tasks. Purpose To evaluate the impact on drug costs, patient chair time and safety profile of switching from the intravenous to the subcutaneous formulation of trastuzumab Material and methods A retrospective study of all patients with HER2+ breast cancer who received trastuzumab from March 2015 to March 2016 in our hospital was conducted. Data collected were: age, body weight, route of administration, number of cycles and dose per cycle. Costs were calculated based on the use of vials and the trastuzumab posology (Tsc fixed dose 600 mg; Tiv 1 loading dose (8 mg/kg) plus maintenance cycles (6 mg/kg). Patient time in the infusion chair was considered 5 min for Tsc and 90 min for a loading dose of Tiv and 30 min for a maintenance dose of Tiv. Results 74 patients were included: 44 were switched from Tiv to Tsc, and 30 started with Tsc. Median age was 60 years (35–87) and median body weight was 63 kg (42–103). Patients received a median of 10 cycles (1–18) and 378 mg (252–618) per cycle. Subcutaneous administration was cheaper above 63 kg in body weight. In spite of having patients with a median body weight of 63 kg, the savings generated by the change in administration to subcutaneous were €39 836. This was due to the difference in dosification between both treatment options. Tsc administration led to a six-fold reduction in patient chair time (447 hours). Tsc was well tolerated. Only in 1 patient was switching to the Tiv formulation necessary because of pain at the site of administration after two treatment cycles. Conclusion Switching from Tiv to Tsc was associated with costs savings and reduced chair time, maintaining the safety of the treatment. References and/or acknowledgements De Cock E, et al. A time and motion study of subcutaneous versus intravenous trastuzumab in patients with HER2-positive early breast cancer. Can Med2016;5:389–97. No conflict of interest