OBJECTIVES: Breast cancer is the most common cancer affecting women in Australia with an estimated 20,000 cases diagnosed in 2021. Trastuzumab is the used for the treatment of HER-2 positive breast cancer. It lost exclusivity in 2019 and within a year five biosimilars were reimbursed through the Australian Pharmaceutical Benefits Scheme. Pharmaceuticals in Australia are subject to an initial statutory price decrease followed by an ongoing review of the price through a process called price disclosure. This study sought to investigate the uptake rate, price evolution and budget impact of the reimbursement of trastuzumab biosimilars in Australia.

METHODS: Prescription data was obtained from the Services Australia Medicare Statistics website for the financial years ending 2019, 2020 and 2021. Price disclosure information acquired from the PBS website. Comparisons using summary statistics of before and after loss of exclusivity of number of scripts, costs of trastuzumab to the Australian government as well as the dispensed price of a standard 750 mg dose of trastuzumab.

RESULTS: The price of a standard dose of 750mg of trastuzumab dropped from AU$4,564 to $1,698 (=-62.8%) from July 2019 to December 2021. This resulted a drop in costs to the Australian Government from AU$155.9M to AU$99.7M (= -36.0%). The number of dispensed trastuzumab scripts increased from 56.0K to 63.2K (= +12.8%) in the same period. The originator brand of trastuzumab was removed from the PBS in October 2021 at the request of the manufacturer.

CONCLUSIONS: In just two years a 62.8% drop of the price of trastuzumab resulted in an almost $60M savings for the Australian government. This happened despite a 12.8% increase in trastuzumab scripts dispensed. Uptake of biosimilar trastuzumab in Australia has been very successful leading to significant cost savings that can be reinvested into the health care system.