Eli Lilly and Company announced that following a pre-planned interim analysis for MONARCH 2, an independent Data Monitoring Committee (DMC) provided the recommendation to continue the study without modification as the interim efficacy criteria were not met. The MONARCH 2, phase 3 trial compares abemaciclib plus fulvestrant versus placebo with fulvestrant in women with hormone-receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) locally advanced or metastatic breast cancer.

"We had stringent criteria set for this interim analysis and we look forward to receiving the final MONARCH 2 results in the first half of 2017," said Richard Gaynor, M.D., senior vice president, product development and medical affairs for Lilly Oncology. "We remain optimistic that treatment with abemaciclib, in combination with fulvestrant could offer improved outcomes for patients."

The phase 3, double-blind study, designed to evaluate the safety and efficacy of abemaciclib in combination with fulvestrant, was conducted across 142 sites worldwide. The intent-to-treat population of 669 patients was randomized to receive abemaciclib or placebo orally every 12 hours on a continuous dosing schedule, given in combination with fulvestrant at the approved dose and schedule, until disease progression. Patients enrolled in the study had experienced disease progression on or within 12 months of receiving endocrine treatment in the neoadjuvant or adjuvant setting or while receiving first-line endocrine therapy for metastatic disease. Patients who had received chemotherapy in the metastatic setting were not eligible for the study. The primary endpoint for MONARCH 2 is progression-free survival (PFS).

The trial will continue into the first half of 2017 and will include a final analysis of PFS, overall survival and safety data.

Lilly will await further data and continue to work with the FDA to inform its submission plan for single-agent abemaciclib, based on the MONARCH 1 study. This phase 2 study evaluated the single-agent activity and safety of abemaciclib in patients with refractory metastatic breast cancer, whose disease had progressed following multiple prior treatments, including chemotherapy.

Along with MONARCH 1 and MONARCH 2, Lilly currently has three additional MONARCH trials evaluating abemaciclib in breast cancer. MONARCH 3 is a phase 3 trial of abemaciclib in combination with a nonsteroidal aromatase inhibitor in patients with HR+, HER2- locoregionally recurrent or metastatic breast cancer. Additionally, there are two phase 2 MONARCH trials: neoMONARCH, which is evaluating abemaciclib in combination with a nonsteroidal aromatase inhibitor in the neoadjuvant setting, and monarcHER, which is evaluating abemaciclib plus trastuzumab (with or without fulvestrant) in women with HR+, HER2+ locally advanced or metastatic breast cancer.

Abemaciclib (LY2835219) is an investigational, oral cell cycle inhibitor, designed to block the growth of cancer cells by specifically inhibiting cyclin-dependent kinases, CDK 4 and CDK 6. In many cancers, uncontrolled cell growth arises from a loss of cell cycle regulation due to increased signaling from CDK 4 and CDK 6. Abemaciclib inhibits both CDK 4 and CDK 6, and was shown in cell-free enzymatic assays to be most active against Cyclin D 1 and CDK 4.  

In 2015, the US Food and Drug Administration granted abemaciclib Breakthrough Therapy Designation based on data from the breast cancer cohort expansion of the company's phase 1 trial, JPBA, which studied the efficacy and safety of abemaciclib in women with advanced or metastatic breast cancer. In addition to its current MONARCH clinical trials evaluating abemaciclib in breast cancer, a phase 3 trial of abemaciclib in lung cancer is also underway.