1. CDK4/6 Biomarkers: Issues and Opportunities

2. Topics of Discussion

3. Introduction

4. The Need for Prognostic Biomarkers

5. Genomic Tests to Identify Long-Term Responders to Endocrine Therapy Alone

6. Circulating DNA to Identify Failures to Conventional Therapy

7. Four Populations of Patients Regarding Prognosis

8. Questions

9. Efficacy of Abemaciclib According to HR Status

10. PALOMA-3 Final Analysis: Effect by ER and PR Expression Level in Patients With HR-Positive MBC

11. PIK3CA Mutation and Resistance to CDK4/6 Inhibitors

12. ESR1 Mutations and Resistance to CDK4/6 Inhibitors

13. Hypothesis: Can the Amplification of Cyclin D1 Predict Sensitivity?

14. Hypothesis: Can the Loss of p16 Be Predictive for Sensitivity?

15. CCND1 Amplification and/or p16 Loss and Efficacy of CDK4/6 Inhibitors

16. Two Hypotheses Related to pRb

17. pRB Expression and Efficacy of CDK4 Inhibitors

18. Modulation of pRb and Clinical Efficacy

19. Modulation of pRb and Clinical Efficacy (cont)

20. Take-Home Messages

21. Mechanisms of Adaptation and Resistance

22. Future Treatment Landscape for Endocrine Sensitive Patients*

23. Concluding Remarks

24. Abbreviations

25. Abbreviations (cont)