Journal Article

Assessing Thrombotic Risk in Patients with HR+/HER2- Breast Cancer Receiving CDK4/6 Inhibitors: Insights from Real-World Data from the Middle East

Refae, Sadal, Alsuhebany, Nada, Alqahtani, Tariq, Abdelhafiez Jnr, Nafisa, AlDoughaim, Maha, Alyousef, Saleh, Aljardan, Sultan, Alanazi, Ahmed, Abu Alnasr, Rawan, Althumali, Ibtihal, Bakhribah, Hatoon, Aldawish, Bandar, Alzahrani, Mohammed, Alfehaid, Lama

2026

Overview

Hormone receptor-positive, HER2-negative (HR+/HER2-) is the most common subtype of breast cancer in women. Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, such as palbociclib, ribociclib, and abemaciclib play an important role in the treatment of advanced HR+/HER2- breast cancer. However, CDK4/6 inhibitors might be associated with an increased risk of thrombotic events, including venous thromboembolism (VTE). We conducted a retrospective study at two centers in Saudi Arabia, analyzing data from 447 patients treated with CDK4/6 inhibitors for HR+/HER2- breast cancer between 2016 and 2023. Patients with early-stage, high-risk breast cancer receiving abemaciclib for at least one month were included. The primary outcomes were the incidence of VTE and arterial thrombosis. A total of 505 patients were screened in which 447 breast cancer patients receiving CDK4/6 inhibitors were included. Majority of patients were on palbociclib (70.4%), followed by abemaciclib (28.8%), and then ribociclib (0.67%). The thrombotic events were 11.8% (n=53), with 37.7% of these being pulmonary embolism (PE) and 18.8% symptomatic deep vein thrombosis (DVT). Patients with a prior history of VTE had a significantly higher risk of thrombosis (p=0.03). Abemaciclib was associated with a higher incidence of thrombosis (16.3%), followed by palbociclib (10.2%), and none of the three patients on ribociclib developed thrombosis. The median time to develop thrombosis while receiving CDK4/6 inhibitor therapy was 11.8 months. There was no significant difference in overall survival in breast cancer patients who developed thrombosis compared to patients without thrombosis (p=0.55). This study shows a higher incidence of thrombotic events in real-world settings than clinical trials, emphasizing the need for risk assessment and possible thromboprophylaxis in patients receiving CDK4/6 inhibitors. Future risk assessment tools needed to be applied in breast cancer patients receiving CDK4/6 inhibitors and risk of developing thrombosis.

• Publisher: Dove Press,Dove Medical Press
• Subject: Breast cancer / CDK4/6 inhibitors / deep vein thrombosis / DVT / Hormone receptor-positive / Original Research / pulmonary embolism / Real-world data / thrombosis risk assessment / Thrombotic risk / Venous thromboembolism