US FDA approval for Abemaciclib (Verzenio) ushers in new hope for breast cancer patients
Abemaciclib works by blocking the function of two proteins called cyclin-dependent kinase 4 (CDK4) and CDK6. These proteins play a role in driving cell multiplication, which is key for tumor growth.
The approval of abemaciclib in combination with fulvestrant was based on results from the MONARCH 2 phase III clinical trial. The results, which were published recently in The Journal of Clinical Oncology, showed that adding abemaciclib to fulvestrant improved progression-free survival for patients who had not received chemotherapy after their HR-positive, HER2-negative breast cancer had progressed during or following endocrine therapy. The median progression-free survival was 16.4 months among those who received abemaciclib and fulvestrant, compared with 9.3 months among those who received fulvestrant and placebo.
The approval of abemaciclib as a stand-alone treatment was based on results from the phase II MONARCH 1 clinical trial that were published recently in the AACR’s journal Clinical Cancer Research. In this study, abemaciclib was tested as a treatment for patients who had metastatic HR-positive, HER2-negative breast cancer that had progressed during or following endocrine therapy and whose metastatic disease had been treated with at least one cytotoxic chemotherapeutic. In brief, the data showed that 19.7 percent of the 132 patients who received abemaciclib as part of the trial had complete or partial tumor shrinkage.
Abemaciclib is the third CDK4/6 inhibitor to be approved by the FDA for treating certain patients with advanced or metastatic HR-positive, HER2-negative breast cancer. Palbociclib (Ibrance) was the first to be approved in February 2015 and ribociclib (Kisqali) the second, in March 2017.