AstraZeneca Announces China Approval of Fulvestrant in Combination with CDK4/6 Inhibitor Abemaciclib for HR+/HER2- Advanced Breast Cancer

Source: Pharma Insights

On the evening of August 27, AstraZeneca China announced that China's National Medical Products Administration (NMPA) has officially approved the combination therapy of fulvestrant injection with the CDK4/6 inhibitor abemaciclib for the treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer in patients who have experienced disease progression following prior endocrine therapy. This marks the first approved combination indication for fulvestrant in China, bringing a new treatment option for patients with advanced breast cancer.

Fulvestrant Injection is an estrogen receptor antagonist that binds to, blocks, and degrades estrogen receptors. It is indicated for the treatment of estrogen receptor-positive locally advanced or metastatic breast cancer in postmenopausal women (including natural and induced menopause) whose disease has relapsed following or during adjuvant anti-estrogen therapy, or has progressed during anti-estrogen therapy. Abemaciclib Tablets is a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor. CDK4/6 are activated upon binding to cyclin D.

The key studies related to this approval primarily include:

The MONARCH 2 study is a randomized, double-blind, placebo-controlled phase 3 study conducted in women with HR-positive, HER2-negative locally advanced or metastatic breast cancer. The study results showed:

·The median PFS was significantly prolonged in the abemaciclib plus fulvestrant group, with a median PFS of 16.4 months, compared with 9.3 months in the placebo plus fulvestrant group.

· The overall survival (OS) analysis in the intent-to-treat (ITT) population demonstrated that patients receiving the combination therapy achieved a statistically significant improvement compared with the placebo plus fulvestrant group. The median OS was 46.7 months for the combination therapy group and 37.3 months for the placebo plus fulvestrant group.

· The most commonly reported adverse reactions (≥20%) in the fulvestrant plus abemaciclib group were diarrhea, fatigue, neutropenia, nausea, infection, abdominal pain, anemia, leukopenia, decreased appetite, vomiting, and headache. The most common grade 3 or 4 adverse reactions (≥5%) were neutropenia, diarrhea, leukopenia, anemia, and infection.

Another MONARCH plus study, a randomized, double-blind, placebo-controlled phase 3 trial, evaluated the efficacy and safety of abemaciclib in combination with an aromatase inhibitor and abemaciclib in combination with fulvestrant in predominantly Chinese postmenopausal patients with HR-positive, HER2-negative locally recurrent or metastatic breast cancer.

The study results showed that the median PFS was significantly prolonged in the abemaciclib plus fulvestrant group, with a median PFS of 11.47 months, compared to 5.59 months in the placebo plus fulvestrant group. These results indicate that treatment with abemaciclib plus fulvestrant reduced the risk of disease progression or death in patients by 62.4%.

Breast cancer is one of the most common malignancies among women worldwide. According to publicly available data, approximately 3% to 10% of newly diagnosed breast cancer patients present with distant metastasis at diagnosis. The 5-year survival rate for advanced breast cancer is only about 20%, with an overall median survival time of just 2 to 3 years. Among advanced breast cancer subtypes, HR-positive/HER2-negative disease accounts for approximately 60%. As an incurable and heterogeneous malignancy, HR-positive advanced breast cancer severely impacts women's lives and health, underscoring an urgent need for novel therapeutic regimens to improve prognosis.

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