Eli Lilly’s experimental breast cancer combination has reached its primary endpoint in a key phase 3 trial investigating its use in advanced disease. 

The MONARCH 2 trial compared the combination of abemaciclib (LY2835219) plus fulvestrant (AstraZeneca’s Faslodex) to placebo plus fulvestrant in 669 intent-to-treat breast cancer patients.

The abemaciclib/fulvestrant combination significantly extended progression-free survival (PFS) in women with hormone receptor (HR) positive, human epidermal growth factor receptor-2 (HER2) negative, advanced breast cancer who have relapsed or progressed post-endocrine therapy, compared to the placebo group.

The most common adverse events reported were diarrhoea, neutropenia, nausea and fatigue.

“We are excited about the outcome of our first Phase 3 study for abemaciclib. These data are an important milestone in our goal of bringing abemaciclib to patients with advanced breast cancer, and we look forward to our upcoming conversations with regulators,” said Levi Garraway, senior vice president of global development and medical affairs at Lilly Oncology.

Based on the new data obtained from the MONARCH 2 trial, Lilly intends to submit a new drug application (NDA) for abemaciclib in Q3 of this year, following an NDA for single-agent abemaciclib in Q2 based on data from the MONARCH 1 study. The latter NDA will be for the treatment of refractory metastatic breast cancer patients whose disease has progressed following multiple prior treatments, including endocrine therapy and one to two chemotherapy regimens in the metastatic setting.

Lilly also has its ongoing phase 3 MONARCH 3 trial investigating abemaciclib combined with a non-steroidal aromatase inhibitor in patients with HR+, HER2- advanced breast cancer, as well as monarcHER – a phase 2 trial evaluating abemaciclib plus trastuzumab with or without fulvestrant in women with HR+, HER2+ locally advanced or metastatic breast cancer.

The specifics of abemaciclib’s efficacy will likely be presented at the upcoming American Society of Clinical Oncology (ASCO) meeting in June where it will hope to out-do Pfizer’s Ibrance (palbociclib). The market leader achieved an impressive PFS of 9.2 months versus 3.8 months for fulvestrant in the company’s PALOMA-3 trial.