Treatment of palbociclib in hormone receptor positive breast cancer: a real-world study and efficacy prediction model / 中华肿瘤杂志

ABSTRACT

Objective: To summarize the clinical use of palbociclib and evaluate its efficacy and safety in hormone-receptor (HR)-positive advanced breast cancer patients. Methods: We retrospectively analyzed data from 66 HR-positive metastatic breast cancer patients treated with palbociclib and endocrine therapy at the Department of Oncology in the First Affiliated Hospital with Nanjing Medical University between 2018 and 2020. We evaluated the factors affecting the efficacy of palbociclib using Kaplan-Meier method and Log-rank test for survival analysis and Cox regressions for multivariate analysis. Nomogram model was built for predicting prognosis among HR-positive breast cancer patients who received palbociclib. Concordance index (C-index) and calibration curve were used for internal validation to assess the predictive ability and conformity of the model. Results: Of the 66 patients treated with palbociclib, 33.3%(22), 42.4%(28) and 24.2%(16) patients were treated without endocrine therapy, first-line endocrine therapy, second-line or above endocrine therapy after recurrence, respectively. 36.4%(24) patients had hepatic metastasis, 16.7% (11) patients were sensitive to previous endocrine therapy, 27.3%(18/66) patients had primary resistance to endocrine therapy, while 56.1% (37) patients had secondary resistance to endocrine therapy. The overall response rate was 14.3% (95% CI 6.7%, 25.4%) and clinical benefit rate was 58.7% (95% CI 45.6%, 71.0%). Better clinical outcomes were associated with non-hepatic metastasis (P=0.001), sensitive/secondary resistant to previous endocrine therapy (P=0.004), no or only one line of chemotherapy for metastatic breast cancer (P=0.004), recent pathological confirmation of immunohistochemical analysis (P=0.025). Hepatic metastasis (P=0.005) and primary resistance to endocrine therapy (P=0.016) were the independent risk factors of progression free survival. The C-index of predictive probability for the nomogram constructed from the patient clinical characteristics (whether liver metastasis, whether primary endocrine resistance, lines of chemotherapy after metastasis, lines of endocrine therapy, number of metastatic sites, and time to last immunohistochemistry) to predict the progression-free survival at 6 and 12 months for patients was 69.7% and 72.1%, respectively. The most common adverse events were hematologic toxicities. Conclusions: Our report indicates that palbociclib combined with endocrine therapy for HR-positive recurrent metastatic breast cancer is effective and safe; patients with hepatic metastases and primary resistance to endocrine therapy have worse prognoses and are independent risk factors for progression after palbociclib therapy. The constructed nomogram could help predict the survival and guide the use of palbociclib.