Now four years into a first-in-class FDA approval for certain HR-positive, HER2-negative early breast cancers, Eli Lilly’s Verzenio has proven it can extend patients’ lives in the indication.
Verzenio, used on top of endocrine therapy, significantly reduced the risk of death by 15.8% versus endocrine therapy alone in patients with HR+/HER2-, node-positive, high-risk early breast cancer. That's according to results to be shared at the European Society for Medical Oncology (ESMO) Congress 2025 starting this week.
For a disease setting with curative intent, the overall survival win was a long time coming, after a median follow up of 6.3 years of the monarchE trial that had originally earned Verzenio its early breast cancer nod in October 2021.
The positive overall survival data could give Verzenio’s profile an extra glow in its competition with Novartis’ Kisqali, which, 13 months ago, secured a broader FDA label in early HR+/HER2- breast cancer that also includes patients without nodal involvement. And Lilly’s oncology chief, Jake Van Naarden, and Lilly’s chief medical officer, David Hyman, M.D., hope the latest trial win could increase the adoption of Verzenio and, by extension, the CDK4/6 inhibitor class in early breast cancer.
Currently, about 40% of early breast cancer patients who are eligible for Verzenio are not getting either Verzenio or Kisqali, according to Van Naarden. And overall survival has historically been able to bring some skeptics off the sidelines for a class of medicines, Hyman said.
In an article published in the journal ecancer back in 2022, three oncologists from India, Belgium and Canada argued against the adoption of Verzenio in early-stage breast cancer partly due to uncertainties around its overall survival benefit in monarchE. The three researchers argued that the relationship between invasive disease-free survival—based on which Verzenio got its FDA approval—and overall survival was not clear in HR+/HER2 breast cancer.
“If you didn’t find the endpoints like […] invasive disease-free survival and distant relapse-free survival sufficiently compelling […] now we’ve reached the ultimate gold standard. So there’s really no data-based reason not to utilize these medicines,” Hyman said.
While Van Naarden hopes the data could push the CDK4/6 adoption rate higher than 60%, especially given that Verzenio is dosed for a finite two years, he recognized that reaching 100% is not realistic.
Critics will likely still look for imperfection in monarchE. For example, the three authors of the ecancer editorial suggested that even an overall survival gain would not prove early receipt of CDK4/6 inhibitors in the adjuvant setting is better than saving these medicines for metastatic disease if patients in the control arm haven’t received CDK4/6 inhibitors at relapse.
In monarchE, among patients with distant recurrence who entered post-treatment follow-up, 83.4% in the control arm got any first-line systemic treatment, including 47.3% who got a CDK4/6 inhibitor.
But not relapsing to the metastatic stage is important, Hyman argued, because that’s when the disease becomes incurable, which bodes ill for long-term survival.
The 15.8% magnitude of death risk reduction isn’t the most impressive seen in the oncology world. But Hyman noted that the early-stage breast cancer setting is very different from a metastatic setting in that patients generally do very well, and that trials take a long time to accumulate events to show a big benefit. For now, even at the seven-year mark, about 85% of patients in the control arm were still alive, versus 86.8% in the Verzenio arm.
Van Naarden and Hyman pointed to a slide in monarchE’s ESMO presentation by Stephen Johnston, M.D., Ph.D., from the Royal Marsden NHS Foundation Trust in London, showing past clinical data that had led to practice changes in HR+ early breast cancer. For example, the 2015 result comparing aromatase inhibitors against tamoxifen showed a 15% reduction in the risk of death, with a 2.1-percentage-point absolute difference in breast cancer mortality at 10 years.
While the effect size may look small, the impact is large considering the many people that can be saved with Verzenio, Hyman said. By Lilly’s account, about 90% of the 2.3 million new breast cancer cases each year worldwide are detected at an early stage, and about 70% of all breast cancer cases are HR+/HER2-.
Besides, current data suggest Verzenio’s overall survival advantage will likely expand with longer follow-up. While 9.4% of patients in the control arm were living with metastatic disease at the data cutoff, the rate was lower at 6.4% for the Verzenio group.
As to the in-class competition with Kisqali, Van Naarden suggested that the two drugs’ different tolerability profiles mean some patients may be better off with the Novartis option. Moreover, because Kisqali has established a leadership role in first-line metastatic treatment, some doctors may choose Kisqali for all their patients for simplicity, he explained. But, so far, about 80% of the new patient starts in their overlapping population are still going to Verzenio, the Lilly exec said.
Lilly is spending a lot of efforts these days educating doctors about dose reductions rather than dose interruptions to help manage side effects and, by helping patients stay on treatment, improve Verzenio’s real-world performance, Van Naarden said. The company now plans to package that educational information with the new survival data in conversations with doctors if it gets the label.