Abemaciclib (Verzenio, Eli Lilly) in combination with standard adjuvant endocrine therapy (ET) has met the primary endpoint of invasive disease-free survival (IDFS), significantly decreasing the risk of breast cancer recurrence or death compared to standard adjuvant ET alone in a recent study.

The results are from the pre-planned interim analysis of the phase 3 monarchE study, making abemaciclib the only cyclin-dependent kinase 4/6 inhibitor to demonstrate a statistically significant reduction in the risk of cancer recurrence for people with high risk hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer, according to the press release.

"When a person is diagnosed with high risk early stage breast cancer, they strive to do everything in their power to prevent a recurrence. And as clinicians, we have the same goal," said Maura Dickler, MD, vice president of oncology, late-phase development, Lilly Oncology, in a press release. "monarchE was intentionally designed for people whose breast cancer is at a high risk of returning. We are incredibly excited by the results of monarchE and that we can potentially offer a new treatment option for patients with high risk HR-positive, HER2-negative early breast cancer. This would not have been possible without the tremendous commitment from the people who participated in this trial."

The trial enrolled 5637 patients with high risk, node positive, HR-positive, HER2-negative, early breast cancer who were randomized 1:1 to abemaciclib (150 mg twice daily) plus standard adjuvant endocrine therapy or standard adjuvant endocrine therapy alone. Patients in the abemaciclib arm received treatment for up to 2 years or until discontinuation criteria are met, and all patients receive standard endocrine therapy for at least 5 years if deemed medically appropriate.

The most common adverse reactions observed in the monarchE phase 3 trial include diarrhea, neutropenia, fatigue, infections, nausea, abdominal pain, vomiting, anemia, alopecia, decreased appetite, and leukopenia.

The monarchE trial is set to continue through its estimated completion date of June 2027. At the time of the interim analysis, the IDFS results are considered definitive, according to the press release.

Verzenio® (abemaciclib) Significantly Reduced the Risk of Cancer Returning in People with High
Risk HR+, HER2- Early Breast Cancer. Eli Lilly. https://investor.lilly.com/node/43361/pdf. June 16, 2020. Accessed June 17, 2020.