352P - Cost-effectiveness of CDK4/6 inhibitors in first- vs second-line for advanced breast cancer (ABC) in the phase III SONIA trial (BOOG 2017-03)

Background

Adding cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) to endocrine therapy has improved outcomes in patients with hormone-receptor positive, HER2-negative ABC. The phase 3 SONIA trial randomised 1,050 patients to receive CDK4/6i in first- vs second-line in addition to aromatase-inhibitor in first- and fulvestrant in second-line. No significant difference was found in progression-free survival after two treatment lines (PFS2; HR 0.87; 95% CI 0.74 to 1.03). Here, we report the cost-effectiveness of adding CDK4/6i to first- vs second-line.

Methods

Using patient-level data from SONIA, life years, quality adjusted life years (QALYs) and costs over 5 years were estimated. We accounted for censoring using inverse probability of censoring weights. Based on the administered EQ5D-5L questionnaires, EQ5D-scores were predicted using a linear regression model including clinical characteristics, adverse events and disease progression, stratified by treatment strategy. Healthcare costs (in 2024 Euros) were calculated for drugs, visits, admissions, laboratory, radiology while on SONIA treatment, and subsequent anti-cancer therapies. EQ5D-scores and costs after SONIA treatment were imputed using mean observed values while on SONIA treatment, stratified by treatment strategy. Sensitivity analyses were conducted including an analysis restricted to the SONIA treatment period.

Results

Total life-years and QALYs were comparable in the CDK4/6i first- and second-line group (life years: 3.59 [SD 0.08] vs 3.60 [SD 0.08]; QALYs: 2.78 [0.08] and 2.72 [0.06]), with 0.006 (95% CI -0.065 to 0.316) and -0.060 (95% CI -0.123 to 0.134) incremental life years and QALYs, respectively. Healthcare costs over 5 years in the CDK4/6i first-line group (€61,821 [SD 1,798]) were higher compared to the CDK4/6i second-line group (€39,057 [SD 1,835]), with a mean difference of €22,764 (95% CI €18,329 to €26,734), largely driven by higher CDK4/6i drug costs (+€24,699, 95% CI €22,009 to €28,049). Sensitivity analyses showed similar results.

Conclusions

Adding CDK4/6i to second-line endocrine therapy instead of first-line in patients with ABC yields similar QALYs per patient, but with substantially lower healthcare costs.

Clinical trial identification

NCT03425838.

Editorial acknowledgement

Legal entity responsible for the study

BOOG Study Center.

Funding

The Netherlands Organisation for Health Research and Development and Dutch Health Insurers.

Disclosure

I.R. Konings: Financial Interests, Institutional, Research Grant, outside the submitted work: Novartis, Gilead; Financial Interests, Institutional, Other, Travel grant, outside the submitted work: Daiichi Sankyo, AstraZeneca. E.J. Siemerink: Financial Interests, Personal, Research Funding, outside the submitted work: Pfizer, Novartis. G.S. Sonke: Financial Interests, Institutional, Advisory Board, outside the submitted work: Agendia, AstraZeneca, Novartis, Seagen, Roche; Financial Interests, Institutional, Research Funding, outside the submitted work: Merck. A. Jager: Financial Interests, Institutional, Research Grant, outside the submitted work: Pfizer, Novartis. H.M. Blommestein: Financial Interests, Institutional, Research Grant, outside the submitted work: CADTH, ZIN, Medical Delta; Financial Interests, Institutional, Advisory Board, outside the submitted work: Pfizer. All other authors have declared no conflicts of interest.