Variation in uptake and dose reduction of CDK4/6 inhibitors for the treatment of breast cancer in England, 2019–2024: a descriptive observational study using OpenPrescribing Hospitals

Lay summary

There is a growing number of new cancer medicines available for use in England. It is important to know how hospitals use these medicines to check that patients have fair access to treatment and to understand how they are prescribed in everyday practice.

OpenPrescribing Hospitals is a public tool that makes it easy to see how medicines are used in NHS hospitals in England. Using this tool, this study looked at how hospitals use a group of medicines called CDK4/6 inhibitors. CDK4/6 inhibitors are used to treat some types of breast cancer. They include palbociclib, abemaciclib, and ribociclib.

Use of these medicines more than tripled between 2019 and 2024. In 2019 palbociclib was the most commonly used, but by 2024 use of palbociclib and abemaciclib was almost equal, and use of ribociclib had also increased. Cancer Alliances are groups of NHS organisations in the same region that work together to improve cancer care. Patterns of use varied between Alliances. Doctors sometimes lower the dose if a patient has side effects. This is known as a dose reduction. Lower-strength tablets were commonly used for palbociclib and abemaciclib. This suggests that dose reductions were common, although the data could not confirm why lower strengths were used.

This study shows how OpenPrescribing Hospitals can help the public and the NHS see how hospitals take up and use new medicines.

Abstract

Background The number of novel cancer therapies approved for use in England by the National Institute for Health and Care Excellence is increasing. Monitoring the adoption of new therapies is important to assess equity of access and evaluate real-world prescribing practices. OpenPrescribing Hospitals has recently been launched to facilitate analysis of open secondary care medicines data in England. Using this platform, we set out to describe the use of cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, including the frequency of dose reductions, within National Health Service (NHS) hospitals in England between January 2019 and December 2024.

Methods The monthly proportion of each CDK4/6 inhibitor relative to total CDK4/6 inhibitor use was calculated at hospital level. Regional variation was assessed across Cancer Alliances by comparing the proportions of each CDK4/6 inhibitor used within each alliance in 2021 and 2024. Use of lower strength palbociclib and abemaciclib was used as a proxy for dose reductions.

Findings There was more than a 3-fold increase in the use of CDK4/6 inhibitors between 2019 and 2024. In 2019, 78.6%, 11.9% and 9.5% of CDK4/6 inhibitors used were palbociclib, abemaciclib and ribociclib, compared with 40.2%, 41.2% and 18.6% in 2024. There was variation in the relative percentage change in use of each agent by Cancer Alliance. Use of lower strengths was common for both palbociclib (60%) and abemaciclib (63%).

Interpretation Changes in usage appeared responsive to publication of key evidence and regulatory milestones. There was a higher apparent frequency of dose reductions than reported in clinical trials. OpenPrescribing Hospitals is an accessible, publicly available tool for understanding uptake and use of medicines in NHS hospitals in England.