NEW YORK – The US Food and Drug Administration on Tuesday approved Eli Lilly's abemaciclib (Verzenio) combined with endocrine therapy as an adjuvant treatment for certain patients with hormone receptor (HR)-positive, HER2-negative early breast cancer.
The agency approved the CDK4/6 inhibitor combined with tamoxifen or an aromatase inhibitor specifically for early-stage breast cancer patients who have node-positive disease and have a high risk of recurrence based on a Ki-67 score of at least 20 percent. Ki-67 is a marker for cellular proliferation and a high score indicates patients' tumors are aggressive and may spread quickly.
Abemaciclib is already available in the US as a treatment for metastatic breast cancer. The FDA expanded the drug's indication to early-stage disease based on the results of the Phase III monarchE trial, in which more than 5,600 HR-positive, HER2-negative breast cancer patients were randomized to receive either abemaciclib plus endocrine therapy for two years following surgical resection, or just endocrine therapy. Patients in both arms received endocrine therapy for five to 10 years after abemaciclib treatment, depending on their physicians' recommendations.
Among a subgroup of around 2,000 patients with high-risk disease, defined according to positive lymph nodes, disease grade, tumor size, and Ki-67 scores, patients receiving the abemaciclib-containing regimen had a 37 percent lower risk of breast cancer recurrence or death compared to those on endocrine therapy alone.
Overall survival analysis is still ongoing in the study. Oncologists are particularly interested in this endpoint since, as experts noted after an earlier monarchE data readout at the 2020 San Antonio Breast Cancer Symposium, longer follow-up from other adjuvant CDK4/6 inhibitors including palbociclib (Pfizer's Ibrance) ultimately showed minimal benefit.
Eli Lilly, however, has highlighted that its drug has a differentiated CDK4/6 inhibitor profile. "We are pleased with this initial approval in the adjuvant setting and as these data continue to mature, we look forward to further opportunities to work with health authorities to expand the use of [abemaciclib] in this setting," Jacob Van Naarden, president of Lilly Oncology and CEO of subsidiary Loxo Oncology, said in a statement.