Mayo Clinic researchers collaborated on a new study led by Eli Lilly showing that the drug abemaciclib improves survival for people with high-risk, early-stage breast cancer.
In the phase 3 monarchE trial, two years of abemaciclib (Verzenio) plus endocrine therapy reduced the risk of death by 15.8% compared with endocrine therapy alone among patients with a common type of early-stage breast cancer.
The clinical trial enrolled more than 5,600 patients at over 600 sites across 38 countries. All participants had breast cancer that was hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-), a subtype that includes 70% of all breast cancers, and also had cancer in at least one underarm lymph node, a factor linked to higher risk of recurrence.
"This is the first therapy to significantly prolong survival for this patient population in over two decades," says study co-author Matthew Goetz, M.D., a breast medical oncologist at Mayo Clinic Comprehensive Cancer Center. "With the addition of just one drug to standard endocrine therapy, we are not only seeing fewer recurrences but are also reducing the chance for breast cancer death."
These findings, published in the Annals of Oncology, establish abemaciclib plus endocrine therapy as the new standard of care for this high-risk group.
Abemaciclib is a CDK4/6 inhibitor, a type of drug that blocks proteins involved in cancer cell division. It is the first drug in its class approved by the Food and Drug Administration to treat node-positive, high-risk early breast cancer. Dr. Goetz previously led the MONARCH 3 clinical trial, which led to the FDA approval of abemaciclib in combination with hormone therapy for advanced HR+/HER2- breast cancer.
"Abemaciclib was developed to target estrogen receptor-positive breast cancer in a way that's different than chemotherapy by slowing the proliferation of cancer cells," Dr. Goetz says. "We now can confidently state that the benefits seen early on, in terms of reducing recurrence, result in improved survival, which is what matters most to patients."
While most patients with HR+/HER2- breast cancer have good long-term outcomes, those with lymph-node involvement or large or high-grade tumors are more likely to experience recurrence.
Among patients who took abemaciclib with endocrine therapy, 32% fewer experienced disease spread after seven years compared with those who only received endocrine therapy. This confirms that abemaciclib helps lower the risk of recurrence even after treatment with the drug has ended.
Continued follow-up will determine whether the survival benefit deepens over time.
Review the study for a complete list of authors, disclosures and funding.
