Real-world data showed treatment with palbociclib plus endocrine therapy was efficacious in patients with hormone receptor positive, human epidermal growth factor receptor 2 negative (HR+/HER2-) advanced breast cancer. Researchers presented their findings at the 2022 ASCO Annual Meeting.

Investigators studied patient data using electronic health records from 7 cancer centers in China. Patients received treatment with palbociclib and endocrine therapy between May 2018 and December 2020.

There were 194 patients involved in the study, of which 138 patients discontinued treatment due to disease progression (130), financial inability (5), or adverse events (3). Median follow up was 22.4 months. Investigators reported the following outcomes:

• median progression-free survival (PFS) was 12.3 months;
• median time to failure was 11.8 months; and
• median overall survival (OS) was 35.5 months.

At 1 year, researchers found rates of PFS and OS were 50.8% and 87.6%, respectively, while time to failure was 49%. Additionally, among 155 patients who had measurable disease, rates of objective response, disease control, and clinical benefit were 27.2%, 71.6%, and 81.3%, respectively.

Median PFS was significantly longer among patients receiving the treatment combination as first-line therapy compared to second-line, third-line, or higher (mPFS=10.7 and 7.2 months, P<.0001).

Multivariate Cox regression analysis was used to identify risk factors for poorer outcomes. Postmenopausal patients were at higher risk for worse PFS compared to premenopausal patients (HR=1.549, [95% CI, 1.007-2.382], P=.046). Liver metastasis was “a significant risk factor for poor PFS and OS (HR=1.993, [95%CI, 1.243-3.195], P=.004; HR=2.345, [95% CI, 1.089-5.049, P=.029),” while central nervous system metastasis was linked to greater risk of poor OS (HR=2.658, [95% CI, 1.152-6.136], P=.022).

Investigators concluded palbociclib plus endocrine therapy “exhibited favorable efficacy for HR+HER2- [advanced breast cancer] in Chinese real-world practices, especially for non-liver, non-CNS metastasis, or premenopausal patients. Early-line treatment yielded more durable benefits.”

Reference:
Zhang L, Wang H, Yang J, et al. Clinical outcomes and clinical/genetic risk factors of palbociclib plus endocrine therapy (ET) for HR+HER2- advanced breast cancer (ABC) patients in Chinese multicenter study of real-world practices. J Clin Oncol. 2022;40(suppl 16):abstract e13039. doi:10.1200/JCO.2022.40.16_suppl.e13039