September 28, 2017
On September 28, 2017, the Food and Drug Administration approved abemaciclib (VerenzioTM Eli Lilly and Company) in combination with fulvestrant for women with HR-positive, HER2-negative advanced or metastatic breast cancer with disease progression following endocrine therapy. In addition, abemaciclib was approved as monotherapy for women and men with HR-positive, HER2-negative advanced or metastatic breast cancer with disease progression following endocrine therapy and prior chemotherapy in the metastatic setting.
The approval in combination with fulvestrant was based on MONARCH 2, a randomized, placebo-controlled, multicenter trial in women with HR-positive, HER2-negative metastatic breast cancer with disease progression following endocrine therapy who had not received chemotherapy in the metastatic setting. The trial randomized 669 patients to receive either abemaciclib or placebo orally twice daily plus intramuscular injection of 500 mg fulvestrant on days 1 and 15 of cycle 1 and then on day 1 of cycle 2 and beyond (28-day cycles). Patients remained on continuous treatment with abemaciclib until development of progressive disease or unmanageable toxicity. Median progression-free survival for patients taking abemaciclib with fulvestrant was 16.4 months compared with 9.3 months for those taking placebo with fulvestrant (HR 0.553; 95% CI: 0.449, 0.681; p<0.0001). The objective response rate in patients with measurable disease taking abemaciclib with fulvestrant was 48.1% (95% CI: 42.6, 53.6) compared to 21.3% (95% CI 15.1, 27.6) in the placebo with fulvestrant treated patients.
The approval as monotherapy was based on MONARCH 1, a single-arm, open-label, multicenter study in women with measurable HR-positive, HER2-negative metastatic breast cancer whose disease progressed during or after endocrine therapy, had received a taxane in any setting, and who received one or two prior chemotherapy regimens in the metastatic setting. A total of 132 patients received 200 mg abemaciclib orally twice daily on a continuous schedule until progressive disease or unmanageable toxicity. Objective response rate was 19.7 percent (95% CI: 13.3, 27.5) with a median response duration of 8.6 months (95% CI: 5.8, 10.2).
The most common adverse reactions in greater than 20% of patients taking abemaciclib were diarrhea, neutropenia, nausea, abdominal pain, infections, fatigue, anemia, leukopenia, decreased appetite, vomiting, headache, and thrombocytopenia. The most frequently reported (≥5%) grade 3 or 4 adverse reactions in patients taking abemaciclib with fulvestrant were neutropenia, diarrhea, leukopenia, anemia, and infections.
The recommended starting doses are 150 mg twice daily in combination with fulvestrant or 200 mg twice daily as monotherapy.
Full dosing information is available at:
FDA granted priority review and Breakthrough Therapy Designation to abemaciclib for this indication. Approval was granted approximately three months prior to the due date. A description of FDA expedited programs is in the Guidance for Industry: Expedited Programs for Serious Conditions-Drugs and Biologics, available at:
Healthcare professionals should report all serious adverse events suspected to be associated with the use of any medicine and device to FDA’s MedWatch Reporting System by completing a form online at http://www.fda.gov/medwatch/report.htm, by faxing (1-800-FDA-0178) or mailing the postage-paid address form provided online, or by telephone (1-800-FDA-1088).
Pharmacist’s Applications to Practice
Abemaciclib for Hormone Receptor (HR)–Positive, Human Epidermal Growth Factor Receptor 2 (HER2)–Negative Advanced or Metastatic Breast Cancer That Has Progressed After Endocrine Therapy
Author: Andrea M. Clarke, PharmD
PGY-1 Pharmacy Practice Resident
University Health Shreveport
What is the potential role for abemaciclib in the management of metastatic breast cancer?
- Abemaciclib is a cyclin-dependent kinase (CDK) 4/6 inhibitor approved as a treatment option for patients with HR-positive HER2-negative advanced or metastatic breast cancer (MBC) whose disease has progressed after endocrine therapy.1
- Approval by the FDA is based on evidence from the single-arm phase 2 MONARCH 1 study in which treatment with abemaciclib as monotherapy demonstrated an overall response rate of 19.7%, median progression-free survival (PFS) of 6 months, and median overall survival of 17.7 months.2
- Abemaciclib in combination with fulvestrant was examined in the phase 3 MONARCH 2 study, which demonstrated improved PFS of 16.4 months versus 9.3 months when compared to fulvestrant alone.3
- Abemaciclib is the third CDK 4/6 inhibitor to be approved by the U.S. Food and Drug Administration (FDA) for MBC. Abemaciclib is the only CDK 4/6 inhibitor to be approved for use as monotherapy. Palbociclib is approved for use with fulvestrant following endocrine therapy progression but is also approved in the first-line setting when used in combination with letrozole. Ribociclib is approved in the first-line setting when used in combination with letrozole.4
- The National Comprehensive Cancer Network has not yet weighed in on abemaciclib’s role in therapy for MBC.
What role can the pharmacist play in the management of patients on abemaciclib?
- Pharmacists need to be aware of two different dosing recommendations for abemaciclib. When used as monotherapy, abemaciclib is dosed as 200 mg twice daily. When used in combination with fulvestrant, abemaciclib is dosed as 150 mg twice daily.1
- In pre- and perimenopausal patients on abemaciclib in combination with fulvestrant, a gonadotropin-releasing hormone agonist such as goserelin should be added to the regimen.1
- Dosing for patients with severe hepatic impairment (Child-Pugh C) should be reduced to once daily.1
- Monitor for hematologic and nonhematologic toxicities to determine the need for dose modifications as provided in the package insert. Dose modifications are recommended for neutropenia (46% incidence; all grades), diarrhea (90% incidence; all grades), alanine aminotransferase/aspartate aminotransferase (ALT/AST) increases (30% incidence; all grades). Grade 3 or higher neutropenia occurred in nearly one-third of patients, with a median time of onset of 29 days and median duration of 15 days.1-3
- Monitor for signs and symptoms of venous thromboembolism, which has been reported in patients treated with abemaciclib in combination with fulvestrant.1-3
- Abemaciclib is metabolized by cytochrome P450 3A4 (CYP3A4), and patients should be screened for concomitant use with CYP3A4 inhibitors and inducers. If strong CYP3A4 inhibitors are used, dose reduction of abemaciclib to 100 mg twice daily is recommended.1
- Patients should be counseled to take abemaciclib at approximately the same time each day with or without food.1
- A complete blood count with differential, ALT, AST, and serum bilirubin should be assessed prior to the start of therapy and then monitored every 2 weeks for the first 2 months, monthly for 2 months, and then as clinically indicated.1
- When compared with palbociclib and ribociclib, abemaciclib has a lower frequency of hematologic toxicities, in particular neutropenia, but a higher incidence of fatigue and gastrointestinal toxicities, possibly because of abemaciclib’s greater selectivity for CDK4 over CDK6. The lower incidence of neutropenia with abemaciclib allows for continuous dosing, whereas palbociclib and ribociclib are dosed 21 days on and 7 days off.1-3,5,6
- Elevations in serum creatinine (SCr) occurred in most patients (98.5%); however, abemaciclib has been found to inhibit renal efflux transporters that mediate active secretion of creatinine in the kidneys. Therefore, elevation in SCr may not accurately reflect renal function, and other methods of estimating glomerular filtration rate (GFR) that do not reflect active tubular secretion by renal efflux transporters, such as cystatin C-calculated GFR, may reflect renal function more accurately.2,7
- Abemaciclib and its active metabolites cross the blood-brain barrier and reach concentrations in the cerebrospinal fluid that are comparable to unbound plasma concentrations, which may make this an attractive option for patients with brain metastases.1,7,8
- Abemaciclib is supplied as 50 mg, 100 mg, 150 mg, and 200 mg tablets.1
- Although no patient assistance program is currently available to the uninsured, a Verzenio Savings Card is available to patients with commercial insurance and will cover the remaining out-of-pocket costs, providing patients with the first 3 months of therapy at no cost and then for $10/month after that, covering up to a maximum of $25,000/year. Uninsured and government-insured patients are ineligible.9
- Verzenio (abemaciclib) [package insert]. Indianapolis, IN: Eli Lilly and Co.; September 2017.
- Dickler MN, Tolaney SM, Rugo HS, et al. MONARCH 1, a phase II study of abemaciclib, a CDK4 and CDK6 inhibitor, as a single agent, in patients with refractory HR+/HER2- metastatic breast cancer. Clin Cancer Res. 2017; 23(17):5218-5224.
- Sledge GW, Toi M, Neven P, et al. MONARCH 2: abemaciclib in combination with fulvestrant in women with HR+/HER2- advanced breast cancer who had progressed while receiving endocrine therapy. J Clin Oncol. 2017; 35:2875-2884.
- Breast Cancer. Version 2.2017. National Comprehensive Cancer Network. Available at https://www.nccn.org/professionals/physician_gls/pdf/breast.pdf. Accessed October 15, 2017.
- Ibrance (palbociclib) [package insert]. New York, NY: Pfizer Labs; March 2017.
- Kisqali (ribociclib) [package insert]. East Hanover, NJ: Novartis, Inc.; March 2017.
- 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. Cancer Discov. 2016; 6(7):740-753.
- Raub TJ, Wishart GN, Kulanthaivel P, et al. Brain exposure of two selective dual CDK4 and CDK6 inhibitors and the antitumor activity of CDK4 and CDK6 inhibition in combination with temozolomide in an intracranial glioblastoma xenograft. Drug Metab Dispos. 2015;43(9):1360-1371.
- Verzenio Savings Card. Available at https://www.verzenio.com. Accessed October 15, 2017.