Summary
This study has two modules: M1 and M2.
Cohort M1 (monotherapy), will evaluate how safe and tolerable a new drug called AZD8421 is when given alone, and will identify a recommended phase 2 dose (RP2D) in people with ER+ HER- advanced breast cancer who have previously been treated with CDK4/6i (Parts A and B) and participants with metastatic high-grade serous ovarian cancer previously treated with a platinum-based chemotherapy in the metastatic setting (Part B).
AZD8421 will also be evaluated as a combination therapy in M2. In M2, AZD8421 will be administered with a CDK4/6 inhibitor - one or more of abemaciclib, ribociclib and palbociclib and camizestrant (a next generation oral SERD) - in people with ER+ HER- advanced breast cancer who have previously been treated with a CDK4/6 inhibitor.