Impact of Cyclin-Dependent Kinase 4 and 6 Inhibitors on Chemotherapy Utilization and Overall Survival in Women with HR+/HER2– Metastatic Breast Cancer in the United States

Purpose: Delaying chemotherapy remains a vital goal in therapeutic management of HR+/HER2– metastatic breast cancer (MBC). However, recent reports continue to highlight substantially high chemotherapy utilization in earlier therapy lines. In this study, we explored the impact of cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor therapy class, introduced in 2015, on early chemotherapy utilization in an older population of patients with HR+/HER2– MBC in the United States (US). Methods: Using an interrupted time series design, patients with a confirmed diagnosis of MBC aged ≥ 65 years initiating systemic therapy during 2010-2019 were selected from the SEER- Medicare database. The proportion of chemotherapy use was summarized quarterly based on the date of treatment initiation separately in the first, second, and third lines. Segmented regression models, adjusted for autocorrelation over time, were fitted to estimate trends before and after the availability of CDK4/6 inhibitors in the first quarter of 2015. Results: Of the 3,244 eligible women (median age at diagnosis: 74 years), all initiated first-line therapy; 47.9% (n=1,581) initiated second-line therapy, and 50.1% (n=792) initiated third-line therapy. Chemotherapy utilization in the period immediately after introduction of CDK4/6 inhibitor therapy decline by estimated 2.5% in the first line (P=0.408), 15.5% in the second line (P=0.005), and 16.3% in the third line (P=0.003). Conclusions: This population-based study illustrates that chemotherapy utilization in earlier therapy lines for HR+/HER2– MBC declined steadily between 2010 and 2019. These declines were significantly accelerated by the introduction of CDK4/6 therapy class in 2015, notably in the second- and third-line settings.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Pharmaceutic Health Outcomes & Policy

Grantor

University of Houston

Year dc:date.issued

2022

Author dc:creator

• Goyal, Ravi K.

Advisor dc:contributor.advisor

• Johnson, Michael L.

Committee members dc:contributor.committeemember

• Abughosh, Susan M.
• Candrilli, Sean D.
• Chen, Hua
• Holmes, Holly M.

• Metastatic breast cancer
• CDK4/6 inhibitors
• Palbociclib
• SEER Medicare

Statement dc:rights

• The author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/10657/13247

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/13247