by Dr. C.H. Weaver M.D. updated 8/2019
Recently released clinical trial results from the Phase 3 MONARCH 2 study showed that Verzenio (abemaciclib), a cyclin-dependent kinase (CDK) 4 & 6 inhibitor, when administered in combination with fulvestrant, significantly delays the time to cancer progression, and prolongs overall survival compared to treatment with fulvestrant alone in women with hormone-receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), advanced breast cancer.(1,5,6)
About Metastatic Breast Cancer
Breast cancer is the most common cancer in women worldwide with nearly 1.7 million new cases diagnosed in 2012.(2) In the U.S. each year, nearly 232,000 individuals will develop invasive breast cancer and about 40,000 women will succumb to their disease.(3) Metastatic breast cancer is rarely curable, but is often treatable and controllable for many years.
Verzenio is an inhibitor of cyclin-dependent kinases (CDK) 4 & 6. A major hallmark of cancer cells is their ability to multiply rapidly; CDK inhibitors interfere with this process by blocking the activity of enzymes known as CDKs, particularly CDK 4 and CDK 6, that help to regulate cell division. For effectively treating breast cancer, CDK inhibitors are usually combined with endocrine therapy, which works by preventing hormones from binding with their respective receptors on the cancer cells.(4)
In the MONARCH 2 clinical trial 669 patients with advanced breast cancer were treated with either Verzenio plus fulvestrant, or fulvestrant alone and directly compared. The combination therapy achieved an objective response rate of 48.1% compared to 21.3% in patients treated with fulvestrant alone. This translated into a delay in the time to cancer progression. Patients treated with the combination survived 16.4 compared to 9.3 months for fulvestrant alone without cancer progression.(1)
FDA Approves Verzenio™ as Initial Treatment for Advanced Breast Cancer
The U.S. Food and Drug Administration (FDA) has approved Verzenio in combination with an aromatase inhibitor (AI) as initial endocrine-based therapy for the treatment of postmenopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer.(5)
This approval of Verzenio as initial therapy in combination with an AI is based on the pivotal MONARCH 3 clinical trial. MONARCH 3 evaluated Verzenio in combination with an AI as initial endocrine-based therapy in 493 postmenopausal women with HR+, HER2- advanced breast cancer whom had no prior systemic treatment for advanced disease.(5)
Verzenio treated patients remained cancer free for 28-months on average compared to 14.8 months for treatment with an AI alone. Verzenio plus an AI had an objective response rate of 55.4 percent compared to 40.2 percent for treatment with an AI alone. The average duration of response was 27.4 months with Verzenio plus an AI versus 17.5 months for treatment with an AI alone.(5)
Verzenio is now indicated for the treatment of HR+, HER2- advanced or metastatic breast cancer:
- in combination with an aromatase inhibitor for postmenopausal women as initial endocrine-based therapy
- in combination with fulvestrant for women with disease progression following endocrine therapy
- as a single agent for adult patients with disease progression following endocrine therapy and prior chemotherapy in the metastatic setting.
The results of the the MONARCH 2 and 3 clinical trials confirmed the activity of Verzenio identified in the MONARCH 1 trial in132 patients with HR-positive, HER2-negative MBC. Over half of the patients had over 3 sites of cancer metastases, and had received a median of least 3 prior therapies for advanced breast cancer. All patients were treated with abemaciclib. (7)
- Overall anti-cancer responses were achieved in nearly 20% of patients.
- Approximately 23% of patients had stabilization of their cancer lasting for at least 6 months.
- Among patients who achieved an anti-cancer response, the median duration of the response was nearly 9 months; over 70% of patients experienced a median duration of response for at least 6 months, and 28.2% of patients experienced a median duration of response for 12 months.
- The most common side effects of abemaciclib were diarrhea, nausea, fatigue, and loss of appetite.
Cyclin-dependent kinases play a key role in regulating the replication and growth of breast cancer cells and several medicines that target this growth pathway have either been recently approved or are in the development process.
- The data were presented at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract #1000) and simultaneously published online in the Journal of Clinical Oncology.
- World Cancer Research Fund International. Breast Cancer.
- American Cancer Society. Understanding Advanced Cancer, Metastatic Cancer and Bone Metastases. https://www.cancer.org/treatment/understanding-your-diagnosis/advanced-cancer/what-is.html.
- Verzenio [package insert]. Indianapolis, IN: Eli Lilly and Company; 2018.
- Patnaik A, Rosen LS, Tolaney SM, et al. Efficacy and safety of abemaciclib, an inhibitor of CDK4 and CDK6, for patients with breast cancer, non-small cell lung cancer, and other solid tumors [published ahead of print May 23, 2016]. Cancer Discov. 2016;6:740-753.
- Dickler M, et al. MONARCH1: Results from a phase II study of abemaciclib, a CDK4 and CDK6 inhibitor, as monotherapy, in patients with HR+/HER2- breast cancer, after chemotherapy for advanced disease. Proceedings from the 2016 annual meeting of the American Society of Clinical Oncology (ASCO). Abstract #510.