Background Due to the recent commercialisation of subcutaneous trastuzumab (Tsc) for the treatment of HER2+ breast cancer, there is an opportunity to minimise costs with a potential significant impact on the public health system.

Purpose The objective of this study was to assess the cost minimisation achieved by using subcutaneous (600 mg/21 days) versus intravenous trastuzumab (various dosifications) for the treatment of HER2+ breast cancer.

Material and methods A retrospective and descriptive study of all patients who received trastuzumab for the treatment of HER2+ breast cancer from 1 January 2015 to 30 September 2015 was done. The following data were collected: route of administration, associated costs, body weight and number of administrations. The oncology and management databases of the hospital pharmacy service were the sources of information. The different protocols used for intravenous trastuzumab were comparable with the use of 6 mg/kg/21 days. The calculations were made considering this posology. As Tsc is administered at a fixed dose, there could be cost savings in patients above a certain body weight. This body weight was calculated. The cost for each patient was calculated according to the subcutaneous and intravenous dosifications and the number of administrations received.

Results During the study period, 73 patients were treated with trastuzumab: 67 received Tiv (92%) and 6 Tsc (8%). The cost of trastuzumab 600 mg vial (sc) was 1326€ (fixed dose) and Tsc vial 150 mg (iv) 527€. Subcutaneous administration was cheaper above 63 kg in body weigth. 48/73 patients had a body weight >63 kg, and 6 of them (12.5%) received Tsc. The total cost for the 312 intravenous administrations associated with patients >63 kg was 528 587€ compared with 415 833€ theoretical cost for Tsc. The potential cost savings were 112 754€.

Conclusion

1. Two-thirds of patients who received trastuzumab weighted >63 kg.

2. A few patients in this group received Tsc.

3. Most of the patients in the study received a treatment with a higher cost than the new form of subcutaneous trastuzumab.

ConclusionNo conflict of interest.