Efficacy and safety of dalpiciclib combined with endocrine therapy in elderly patients with HR+/HER2- advanced breast cancer: a real-world study.

BACKGROUND: Dalpiciclib shows satisfactory efficacy and safety in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. Nevertheless, relevant real-world evidence is inadequate, particularly in elderly patients. This real-world study intended to explore the efficacy and safety of dalpiciclib plus endocrine therapy in elderly patients with HR+/HER2- advanced breast cancer. METHODS: This single-center retrospective study analyzed the data of 70 elderly patients (≥65 years) with HR+/HER2- advanced breast cancer receiving dalpiciclib combined with endocrine therapy. The median (range) follow-up duration was 13.5 (1.7-29.4) months. RESULTS: The objective response rate (ORR) was 14.3%, and the disease control rate was 94.3%. The ORR was higher in patients with first-line dalpiciclib-based therapy than in those with second-line therapy or above (24.4% vs. 0.0%) (P = 0.004). A total of 39 (55.7%) progression-free survival (PFS) events were recorded. The median (95% confidence interval) PFS was 17.0 (14.6-19.4) months after dalpiciclib plus endocrine therapy. The multivariate Cox regression model disclosed that Eastern Cooperative Oncology Group performance status score 2 (vs. 0) [hazard ratio (HR): 4.010, P = 0.028], lines of dalpiciclib-based therapy (HR: 4.161, P = 0.041), cross-line dalpiciclib (HR: 3.362, P = 0.046), and endocrine resistance (HR: 2.728, P = 0.047) were associated with shorter PFS. The most common adverse events were leukopenia (97.1%) and neutropenia (95.7%), which were predominantly grade 2 or 3. Grade 4 adverse events included leukopenia (2.9%), neutropenia (7.1%), and thrombopenia (1.4%). CONCLUSION: Dalpiciclib plus endocrine therapy possesses acceptable efficacy and safety for the treatment of elderly patients with HR+/HER2- advanced breast cancer.