Palbociclib Plus Aromatase Inhibitors as First-Line Therapy For Metastatic Breast Cancer Patients With Cardiovascular Diseases

In a retrospective analysis, researchers found that using palbociclib in combination with aromatase inhibitors (PAL+AI) as a first-line therapy for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (MBC) and cardiovascular diseases (CVD) was associated with prolonged overall survival (OS) and real-world progression-free survival (rwPFS) compared with AI alone in a real-world setting. The results of this study were presented at the 2023 San Antonio Breast Cancer Symposium.

Although cyclin dependent kinase 4/6 inhibitors (CDK4/6i) such as palbociclib combined with endocrine therapy is considered the first-line standard treatment option for patients with HR+/HER2- MBC, there is limited data regarding its efficacy for patients with MBC and CVD. Therefore, researchers compared the OS and rwPFS of PAL+AI with AI alone in patients with HR+/HER2- MBC and CVD.

To conduct their retrospective analysis, Brufsky and colleagues used the Flatiron Health longitudinal database, which contains electronic health records from more than 3 million actively treated patients with cancer in the United States. Based on the data from the Flatiron database, they found 469 patients with HR+/HER2- MBC and CVD who started PAL+AI as first-line therapy between February 2015 and March 2020.

Researchers defined CVD using the National Cancer Institute-Comorbidity Index, which included myocardial infarction, congestive heart failure, peripheral vascular diseases, and cerebrovascular diseases. They used Cox proportional-hazards models to estimate the efficacy of PAL+AI vs AI alone.

Of the total patients treated, PAL+AI was used in 34.1% of patients (n = 160) and AI alone was used in 65.9% of patients (n = 309). Those treated with PAL+AI were younger, more likely to have de novo MBC, more likely to have more than two metastatic sites, and had a greater likelihood of lung/liver involvement compared with those treated with AI alone.

The study results showed that the adjusted median OS for those treated with PAL+AI was 40.7 months (95% CI, 30.9-56.0) compared with 26.5 months (95% CI, 23.3-37.3) for those treated with AI alone (hazard ratio [HR] = 0.73; 95% CI, 0.54-0.997; p = 0.048). The adjusted median rwPFS was 20.0 months in those treated with PAL+AI (95% CI, 11.7-27.5 months) and 12.5 months (95% CI, 9.7-18.3 months) for those treated with AI alone (HR=0.68; 95% CI, 0.51-0.90; p = 0.007).

“Further studies with larger cohorts and comprehensive assessments of comorbidities are needed to provide additional evidence of outcomes and safety of CDK4/6i plus AI for MBC patients with various comorbid conditions in routine clinical practice,” the authors concluded.

Reference:
Brufsky A, Liu X, Li B, McRoy L, Chen C, Makari D, et al. Real-world effectiveness of palbociclib plus aromatase inhibitors (AI) in metastatic breast cancer patients with cardiovascular diseases. Paper presented at: 2023 San Antonio Breast Cancer Symposium; December 5-9, 2023; San Antonio, TX. Accessed January 2, 2024. https://www.sabcs.org/2023-SABCS.