Real-World Data Analysis of CDK4/6 Inhibitor Therapy-A Patient-Centric Single Center Study

Simple Summary In this study, we investigated the effectiveness of the targeted cancer medication CDK4/6 inhibitors, in patients with breast cancer. These medicaments have been used for nearly a decade, but how well they work can vary greatly from one patient to another. By examining the experiences of 86 patients over a period from November 2016 to May 2020, we aimed to understand what factors might predict better or worse outcomes for patients. We discovered that certain characteristics, like the level of the progesterone receptor in the tumor and whether the cancer had spread to multiple locations or the liver, played a significant role in how long patients benefited from treatment without progression. The study also found that management characteristics during treatment could significantly affect patient outcomes. These insights are crucial for developing personalized management strategies that could lead to better outcomes for people with breast cancer.Abstract Background: The quest to comprehend the real-world efficacy of CDK4/6 inhibitors (CDKis) in breast cancer continues, as patient responses vary significantly. Methods: This single-center retrospective study evaluated CDKi use outside the trial condition from November 2016 to May 2020. Progression-free survival (PFS), time-to-treatment failure (TTF), short-term and prolonged treatment benefit (>= 4 and >= 10 months), as well as prognostic and predictive markers were assessed with Kaplan-Meier and multivariate regression analyses. Results: Out of 86 identified patients, 58 (67.4%) had treatment failure of which 40 (46.5%) were due to progression. Median PFS and TTF were 12 and 8.5 months, respectively. A total of 57 (66.3%) and 42 (48.8%) patients experienced short-term and prolonged treatment benefit. Independent, significant predictors for PFS were progesterone receptor expression (HR: 0.88), multiple metastatic sites (HR: 2.56), and hepatic metastasis (HR: 2.01). Significant predictors for TTF were PR expression (HR: 0.86), multiple sites (HR: 3.29), adverse events (HR: 2.35), and diabetes (HR: 2.88). Aside from tumor biology and adverse events, treatment modifications like pausing and switching of CDKi were predictive for short-term (OR: 6.73) and prolonged (OR: 14.27) therapeutic benefit, respectively. Conclusions: These findings emphasize the importance of tailored treatment strategies, highlighting the role of PR expression, metastatic burden, and therapeutic adjustments in optimizing patient outcomes in real-world breast cancer management.