Anti-hormonal maintenance treatment with/without the CDK4/6 inhibitor ribociclib after 1st line chemotherapy in HR+/HER2- metastatic breast cancer: a phase II trial (AMICA) GBG 97

Background:

Although longer duration of chemotherapy (CT) is associated with longer progression-free survival (PFS) and overall survival (OS) in patients with metastatic breast cancer (MBC), the duration of CT is usually dictated by toxicities and patients' and physicians' preferences, resulting in treatment durations of less than 6 months. Therefore, well tolerated maintenance treatments with the potential to prolong PFS and OS are needed.

Methods:

Patients with hormone receptor (HR)+/HER2- MBC achieving stable disease or tumor response after at least 4 cycles of first-line CT at the discretion of the investigator will be eligible to be randomized 2:1 to receive maintenance endocrine therapy (ET) per investigator's choice with or without the CDK4/6 inhibitor ribociclib. Patients might have received up to one prior line of ET. In both study arms, treatment will be given until disease progression, unacceptable toxicity, or withdrawal of consent. Primary objective is to evaluate the impact of a maintenance ET after first-line CT with or without ribociclib on PFS. Secondary objectives are OS, clinical benefit rate, safety, compliance and patient reported outcomes. Biomarkers predicting response to CDK inhibition and ET in formalin-fixed paraffin-embedded metastatic tissue and blood as well as the role of mutations in ctDNA will be analysed.

150 patients will be recruited. The study is conducted in 20 – 30 sites in Germany.

Conclusions:

The aim of the AMICA study is to demonstrate that maintenance therapy with an endocrine based strategy plus ribociclib significantly prolongs PFS compared to ET alone after first-line CT in patients with HR+/HER2- MBC.