The introduction of a third CDK4/6 inhibitor does not change the cost-effectiveness profile in first and subsequent-lines after progression or relapse during previous endocrine therapy in patients with hormone receptor positive (HR+)/human epidermal receptor-2 negative (HER-2) advanced or metastatic breast cancer.

The aim of this study was to assess the pharmacological costs of CDK4/6-inhibitors (palbociclib, ribociclib and abemaciclib) in hormone receptor positive (HR+)/human epidermal receptor 2-negative (HER2-) advanced or metastatic breast cancer (BC). We have considered pivotal phase III randomized controlled trials (RCTs) of palbociclib, ribociclib and abemaciclib for the treatment of postmenopausal women with HR+/HER2- advanced or metastatic BC in first-line in association with letrozole or anastrozole (scenario 1) and in subsequent-lines after progression or relapse during previous endocrine therapy (scenario 2).The costs of drugs are at the Pharmacy of our Hospital and are expressed in euros (€). Six phase III RCTs, including 3843 patients, were considered. In the scenario 1, abemaciclib resulted the less expensive at the full dose, with 2246 € per month of progression free survival (PFS)-gained. Overall ribociclib resulted the less expensive considering the reduction in dosage (36.1% in MONALEESA-2 trial versus (vs). 36.0% of palbociclib in PALOMA-2 trial vs. 43.4% of abemaciclib in MONARCH-3 trial). The price was the same for palbociclib and abemaciclib both at full and with dose reduction. In the scenario 2, the situation was similar to the scenario 1, but with lowest costs for ribociclib per month PFS-gained both at full dose (2070 €) and at dose reduction (1391 € and 690 € at 400 mg and 200 mg, respectively). Combining pharmacological costs of drugs with the measure of efficacy represented by the PFS, ribociclib was the less expensive in both scenarios.