Safety and patient-reported outcomes in patients with hormone receptor-positive, HER2-negative advanced breast cancer treated with CDK4/6 inhibitors in China: A cross-sectional study.

1054 Background: It is reported that the adverse event (AE) profile may vary with different CDK4/6 inhibitors. With the prolongation of survival, AEs occurred during the treatment period may affect quality of life (QoL) for patients with advanced disease. Currently, there has been no study focusing on the safety and patient-reported outcomes in Chinese patients treated with different CDK4/6 inhibitors. Methods: This was a large cross-sectional study conducted at 10 sites in China. Randomly selected patients with hormone receptor-positive, HER2-negative advanced breast cancer and their physicians were asked to fill the self-designed questionnaires. Disease characteristics and AEs were collected from the perspectives of both patients and physicians, while the patient questionnaire additionally included feedback on the AE management and the European Organization for Research and Treatment of Cancer (EORTC) Quality-of-Life Questionnaire-breast cancer module (QLQ-BR23). Results: Between Jan 30, 2023 and Sep 15, 2023, a total of 1254 patients (median age, 55 years) were included; 212 (16.9%) patients were treated with palbociclib, 483 (38.5%) with abemaciclib, 550 (43.9%) with dalpiciclib, and 9 (0.7%) with ribociclib. Of them, 197 (15.7%) had switching history or dose adjustment of CDK4/6 inhibitor, with the main reason being AEs (51.8%). From the perspective of physicians, the most common AEs for patients were decreased white blood cell (63.3%), decreased neutrophil count (58.7%), and diarrhea (36.3%). The incidence of increased alanine aminotransaminase (ALT) and increased aspartate aminotransaminase (AST) was 9.3% (grade ≥3, 6.0%) and 8.4% (grade ≥3, 6.7%), respectively. Dalpiciclib showed the lowest incidence of increased ALT (3.5%; grade ≥3, none), increased AST (4.2%; grade ≥3, none), and diarrhea (10.5%) compared with other CDK4/6 inhibitors (P6 months of treatment (12.59 vs 27.78 vs 17.95, P6 months).