Is Clinical Risk Score a Useful Predictive Marker of Early Recurrence Among Metastatic Breast Cancer Patients Treated with CDK4/6 Inhibitors?

Objectives: The addition of CDK4/6 inhibitors to standard hormonotherapy improved progression-free survival(PFS) of hormone-positive, HER-2 negative metastatic breast cancer(mBC). We analyzed clinicopathological risk factors predicting early recurrence in mBC patients treated with a combination of CDK4/6 inhibitor and hormonotherapy. Methods: 229 patients were included, and 95 recurrences were seen. Median ER and PR expressions, ki67 levels, metastatic sites, number of metastasis, and grade were related to recurrence. Patients were classified according to the presence of prognostic factors: group 1 included patients with 0-1 risk factors, group 2 with 2-3 risk factors, and group 3 with ≥4risk factors. Results: Median ER, PR, and ki67 levels were 90, 60, and 25,respectively. Median ER, PR, Kİ67, grade, metastatic site, and the number of metastasis were related to PFS. Advanced CDK4/6 line and response were significant for PFS.Median PFS was 6.5 months for recurrent patients. According to the predictive model, patients who recurred before 6.5 months had a high-risk group (group 2,3). PS, family history, CDK4/6 inhibitor types were found to be related to PFS among the recurrent group. Conclusion: There is a need for a prospective design study to determine the clinicopathological markers identifying early recurrence under CDK4/6 inhibitors so new combination therapies or alternatives can be developed. [ABSTRACT FROM AUTHOR]