SC trastuzumab cost-saving for HER2-positive breast cancer in Hong Kong

A cost minimization analysis based on a literature review and Hong Kong data suggests that using subcutaneous (CS) instead of intravenous (IV) trastuzumab for HER2-positive breast cancer (BC) patients can offer an annual saving of more than USD 8.3 million to the Hong Kong healthcare system.

According to the latest available data, BC is the most common female cancer and the third most common cancer overall in Hong Kong. [Hong Kong Cancer Registry, 2020: https://www3.ha.org.hk/cancereg/topten.html] It is estimated that approximately a fifth of all BC patients in Hong Kong are HER2-positive, making them eligible for treatment with HER2-targeted therapies. [Hong Kong Breast Cancer Foundation, Hong Kong Breast Cancer Registry Report No. 8, 2016: http://www.hkbcf.org/download/bcr_report8/hkbcf_report_2016_full_report.pdf]

Trastuzumab, in combination with chemotherapy, is licensed for treatment of HER2-positive early-stage and metastatic BC and is the most commonly used (95.3 percent) targeted therapy for HER2-positive BC in Hong Kong. It is available in IV and SC formulations. IV trastuzumab is dosed according to patients’ body weight and must be reconstituted into solution for a loading dose infusion lasting 90 minutes, followed by maintenance dose infusions lasting 30 minutes. SC trastuzumab is a fixed-dose injection, which takes approximately 5 minutes to administer. The SC formulation has been shown to be noninferior to the IV formulation in terms of efficacy and tolerability. [Ann Oncol 2015;26:320-325] Of note, approximately 90 percent of patients preferred SC over IV trastuzumab in randomized crossover trials. [Ann Oncol 2014;25:1979-1987]

Data from other countries demonstrate that SC trastuzumab provides cost savings vs the IV formulation through minimizing medical resource utilization, in particular, by reducing patient chair, administration and drug preparation times. “However, healthcare systems and modes of clinical services differ between Hong Kong and other countries. Therefore, this study was conducted to investigate cost differences between IV and SC trastuzumab in Hong Kong medical settings, using medical resources utilization data from other countries,” explained the authors of the local study. [Hong Kong Med J 2023;29:16-21]

The researchers developed a cost-minimization model, which compared the direct medical cost of procuring and full-time equivalent (FTE) hours of administering the IV and SC formulations of trastuzumab. The drug acquisition cost was obtained from the manufacturer, whereas the costs for hospitalization and clinic visits were acquired from the Hong Kong Gazette. FTE hours were determined by literature review.

From the eight studies eligible for analysis, the researchers determined that using the SC vs IV formulation saves 0.18 FTE hours of nursing time (7.9 hours) and 0.14 FTE hours of pharmacist time (6.2 hours) per week. “Following 18 treatment cycles [duration of treatment for early-stage HER2-positive BC] with SC trastuzumab, drug acquisition and healthcare professional time costs were reduced by USD 9451.28 and USD 566.16, respectively, compared with IV trastuzumab. Therefore, USD 10,017.44 could be saved for each patient who completes 18 cycles of treatment. Using 2017 data and assuming that the SC formulation was used instead of the IV formulation for all HER2-positive BC patients on trastuzumab, an annual saving of >USD 8.3 million could be achieved in Hong Kong,” reported the researchers.

Drug acquisition costs and patient body weight were included in the model as independent parameters to determine their budget impact. While the cost of drug acquisition was found to have the greatest effect on financial burden, paradoxically, increase in body weight of ≤20 percent had a neutral effect. “This could be related to a substantial amount of drug wastage with weight-based IV trastuzumab, which is consistent with previous findings,” noted the researchers. [Value Health 2015;18:A463]