OBJECTIVES: Patients diagnosed with hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer (aBC) receiving CDK4/6i therapy (ribociclib, palbociclib or abemaciclib), have a probability of having dose reductions for the management of treatment-related serious adverse events (SAEs). The motivation of this study is to quantify the economical impact and the cost optimization of these three therapies in case a dose reduction is needed in this population.

METHODS: An economic model was built to estimate the cost impact when reducing the dose in HR+ HER2- aBC population on day 14 of the treatment cycle within the month of adjustment (standard follow-up visit). A dose reduction was considered for the analysis according to the following pattern only: ribociclib 600mg daily to 400mg daily for 21 days per cycle (one dispensing of 63 tablets of 200mg); palbociclib 125mg daily to 100mg daily for 21 days per cycle (first dispensing of 21 tablets of 125mg and second dispensing of 21 tablets of 100mg); abemaciclib 300mg daily to 200mg daily for 30 days per cycle (first dispensing of 60 tablets of 150mg and second dispensing of 60 tablets of 100mg). Direct costs were included for the treatments from the official source SISMED (USD 2023: 1USD = 4,464COP).

RESULTS: In the scenario where the dose reduction is made at day 14 after the initial dispensing, the total costs are USD$2,678 for ribociclib, USD$4,954 for palbociclib (first and second dispensing USD$2,752-USD$2,202) and USD$5,813 for abemaciclib (first and second dispensing USD$3,488-USD$2,325). The optimization for ribociclib is 89% (11,200mg/12,600mg), 52% for palbociclib (2,450mg/4,725mg) and 49% for abemaciclib (7,400mg/15,000mg).

CONCLUSIONS: Dose reductions due to SAEs could have an economic impact on medication wastage for payers. Ribociclib shows a lower wastage in case of dose reduction and consequently a lower cost impact versus palbociclib and abemaciclib.