Abstract PS10-29: Comparison of healthcare resource utilization and costs in women with HR+/HER2- metastatic breast cancer treated with ribociclib vs palbociclib or abemaciclib
Authors: Balu Sanjeev , Burne Rebecca , Guerin Annie , Bungay Rebecca , Paul Mary Lisha , Sin Roxana 
Published: February 2021

Background: Ribociclib, palbociclib, and abemaciclib are cyclin dependent kinase 4 and 6 (CDK4/6) inhibitors for the treatment of women with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) advanced or metastatic breast cancer (mBC). The economic burden of women with HR+/HER2- mBC treated with different CDK4/6 inhibitors has not previously been compared. Objective: To describe and compare healthcare resource utilization (HRU) and healthcare costs in patients treated with CDK4/6 inhibitors in real-world clinical practice. Methods: Adult women with HR+/HER2- advanced or mBC who initiated treatment with ribociclib, palbociclib, or abemaciclib as the first CDK4/6 inhibitor (index therapy) were identified from IBM MarketScan Data (Q1 2000 - Q3 2018), a large US commercial claims database. HRU and healthcare costs were measured while patients were on treatment with their index CDK4/6 inhibitor. Total healthcare costs, measured from a payers' perspective, included medical (inpatient [IP], outpatient [OP], emergency room [ER]) and pharmacy costs, reported per-patient-per-month (PPPM). HRU and healthcare cost components were each separately compared between ribociclib and palbociclib cohorts, and between ribociclib and abemaciclib cohorts, using models adjusting for age, line of therapy, menopausal status, metastatic sites, and comorbidities. Results: A total of 4,320 women were included: 102 initiated ribociclib as first CDK4/6 inhibitor; 4,118 palbociclib; and 100 abemaciclib. The majority in each cohort were postmenopausal (ribociclib: 79%; palbociclib: 92%; abemaciclib: 92%), and received the index CDK4/6 inhibitor as either first-line (ribociclib: 40%; palbociclib: 31%; abemaciclib: 30%) or second-line therapy (ribociclib: 23%; palbociclib: 24%; abemaciclib: 22%). HRU was not statistically different between the ribociclib and palbociclib cohorts, whereas the ribociclib cohort had fewer IP days compared to the abemaciclib cohort (adjusted incidence rate ratio [IRR]: 0.25, 95% CI: 0.09; 0.67). Total healthcare costs were not statistically different between the ribociclib and palbociclib cohorts, although the ribociclib cohort had lower OP costs PPPM compared to the palbociclib cohort (-$1,339, 95% CI: -2,344; -209). Total healthcare costs were statistically lower for the ribociclib cohort compared to the abemaciclib cohort (-$6,519; 95% CI: -9,959; -2,984). IP costs, OP costs, and pharmacy costs (driven by CDK4/6 inhibitor costs) were all significantly lower for the ribociclib cohort vs the abemaciclib cohort (IP: -$3,398, 95% CI: -22,801; -768; OP: -$3,778, 95% CI: -6,502; -1,659; pharmacy costs: -$1,744, 95% CI: -2,881; -564).

Conclusions: HRU while on treatment was similar between ribociclib and palbociclib, while ribociclib had fewer IP days compared to abemaciclib, after adjusting for baseline covariates. Total healthcare costs while on treatment were higher in the abemaciclib cohort compared to the ribociclib cohort, while ribociclib and palbociclib cohorts tended to have similar total healthcare costs.

Ribociclib vs. PalbociclibRibociclib vs. AbemaciclibHRUAdjusted IRRConfidence intervalP-valAdjusted IRRConfidence intervalP-valIP admissions1.09(0.62; 1.91)0.760.67(0.29; 1.53)0.34IP days0.67(0.35; 1.28)0.220.25(0.09; 0.67)0.01*Days with ER services1.44(0.80; 2.57)0.220.76(0.37; 1.59)0.47Days with OP services1.01(0.91; 1.14)0.800.88(0.73; 1.04)0.14PPPM Healthcare costsAdjusted cost differenceConfidence intervalP-valAdjusted cost differenceConfidence intervalP-valTotal healthcare costs-1,013.82(-3,436; 1,924)0.48-6,519.18(-9,959; -2,984)&lt;0.01*Medical costs-1,222.84(-3,275; 1,231)0.32-6,142.36(-9,907; -2,844)&lt;0.01*IP costs-279.61(-1,516; 1,749)0.76-3,397.88(-22,801; -768)0.01*ER costs481.32(-87; 1,503)0.19577.82(-105; 2,449)0.16OP costs-1,338.92(-2,344; -209)0.03*-3,778.20(-6,502; -1,659)&lt;0.01*Total pharmacy costs-28.95(-798; 917)0.91-1,743.98(-2,881; -564)&lt;0.01*CDK4/6 costs120.08(-592; 1,053)0.83-1,631.39(-2,755; -464)0.01*

Citation Format: Sanjeev Balu, Rebecca Burne, Annie Guerin, Rebecca Bungay, Mary Lisha Paul, Roxana Sin. Comparison of healthcare resource utilization and costs in women with HR+/HER2- metastatic breast cancer treated with ribociclib vs palbociclib or abemaciclib [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-29.