Real Practice Evaluation of Cyclin Dependent Kinase 4/6 (CDK4/6) Inhibitors in Treatment from Hormone Receptor Positive (HR+)/Human Epidermal Growth Factor Receptor-2 Negative (HeR-2-) in Advanced Breast Cancer Patients

Background: As the most frequent cancer overall & the leading cause from cancer-related deaths among women, breast cancer is a major global public health concern. Clinical, morphological, & molecular therapy from breast cancer vary due to its complexity & heterogeneity. CDK 4/6 inhibitors are the mainstay therapy for hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer. We don't have enough data on the three (CDK) 4/6 inhibitors & how to chose them for specific patients. Aim: This study aimed to select the most effective treatment between three types of CDK4/6 inhibitors, reduce the possible toxicities may occur from the drugs & achieve maximum benefit from the drugs with hormonal receptor positive in advanced breast cancer in Ismailia. Patients & methods: A retrospective cohort study was conducted. Study conducted in Ismailia (Suez Canal university hospitals oncology center). Advanced hormone receptor–positive, HER2-negative breast cancer patients taking CDK4/6 inhibitors as first-line treatment who experienced progression & recurrence following previous endocrine therapy. Patients were monitored monthly for 18 months. Survival & toxicity at last follow-up. First clinic visits included a personal & clinical history and physical evaluation for research participants. This research involves 60 female metastatic breast cancer patients who were hormonal positive/her2 negative & monitored for 18 months for CDK4/6 inhibitor toxicity. Results: The results from this study showed the distribution from progression free survival (PFS), which Ribociclib was effective & well -tolerated with longer Progression free survival (PFS) from (79.9%) from patients who had received it, whereas progression free survival in patient who received Abemaciclib & Palbociclib after 18 months from follow up duration was (64.7% & 76% respectively). The difference between groups was statistically insignificant (p). Overall survival (OS) after 18 month duration among studied groups, was 95.2%, 66.7% & 100% in Ribociclib, Abemaciclib & Palbociclib groups, respectively illustrated which there was statistically significant difference between studied groups regarding Overall survival from breast cancer (p=0.043).Conclusion: Ribociclib, abemaciclib, & palbociclib have been shown to slow disease progression & improve patient outcomes in hormone receptor-positive (HR+) & HER2-negative advanced breast cancer patients. All three medications are successful with endocrine therapy, but their toxicity profiles, dosage adjustment needs, & preferred hormonal therapy combinations affect clinical treatment choices.