Treatment Combination Breaks the '5-Year Ceiling' in Metastatic Breast Cancer

The combination is the first in advanced or metastatic breast cancer to have a survival benefit extending over five years.

Treatment with Kisqali (ribociclib) plus Femara (letrozole) significantly improved overall survival in patients who are postmenopausal with hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer.

These results from a phase 3 trial were presented during the 2021 ESMO Annual Congress. Of note, Kisqali is the first of its drug type, CDK4/6 inhibitors, to demonstrate a survival advantage in this patient population.

Dr. Gabriel Hortobagyi, a professor in the department of breast medical oncology in the division of cancer medicine at the University of Texas MD Anderson Cancer Center in Houston, told CURE® that these results demonstrate the progress that has been made in breast cancer and that this treatment should be the preferred treatment option for this population.

Patients (668) in the trial were postmenopausal women with HR+/HER2- metastatic breast cancer who had no prior therapy for advanced disease. A total of 334 patients received 600 milligrams of Kisqali for three weeks on and one week off, with 2.5 milligrams of Femara daily. The remaining 334 patients received a placebo in combination with the same Femara dosing.

Patients receiving Kisqali reached a clinically meaningful overall survival benefit, with a median of 63.9 months, compared with the placebo at 51.4 months. Hortobagyi added that four decades ago, the average life expectancy for this type of breast cancer was about 24 months, so these results really highlight a significant progress that has been made for this population.

Anna Pastrano, who is the longest standing patient on this trial, remembers when her doctor suggested the trial. “(I said) let’s try it. Let’s go for it. Whatever to buy me more time,” she told CURE®. Today, she’s benefited from Kisqali for eight years.

Researchers also reported that the overall survival benefit with Kisqali increased over time, with a survival rate of 44.2% at six years. Specifically, at four, five and six years the benefit increased by 5.7%, 8.4% and 12.2%, compared with the placebo. Notably, this is the first report of median survival exceeding five years in a phase 3 trial for metastatic breast cancer.

This benefit has allowed Pastrano to spend more time with her kids and be introduced to her grandson who is just over one year old. “So, it has been a blessing. I am so blessed. And I hope that this medicine works on other people like this medicine has worked on me,” she said.

“… This is significant … (because) for the first time in advanced or metastatic breast cancer, we have broken the five-year ceiling, if you wish. And it shows that we have continued to make progress in this particular aspect of breast cancer,” Hortobagyi noted.

No new safety signals were observed, and a majority of side effects happened within the first year. The most common severe or life-threatening side effects were neutropenia (low white blood cell count; 63.8% with Kisqali, 1.2% with placebo), liver damage (14.4%, 4.8%), fast or chaotic heartbeats (4.5%, 2.1%) and interstitial lung disease/pneumonia (0.6%, none). Hortobagyi noted that side effects can be managed by decreasing dose or interrupting the treatment for a short period of time, but overall, this is a “very safe and well-tolerated regimen.”

Pastrano only experienced headaches and body aches during the beginning of treatment, but the headaches have since only come every so often. She contributes those to her stress.

Another benefit of this regimen is its little impact on quality of life. Hortobagyi mentioned that quality of life was measured since the beginning of the trials in 2013, and through the years it was not negatively affected by the treatment. And in patients who had symptoms due to their cancer, quality of life was actually improved, he added.

Pastrano said that her quality of life will never be the same since she received her cancer diagnosis, “but the medicine did bring a lot of happiness and joy into my life because, you know, I might not even be here today if it wasn’t for the clinical trial.”

She concluded that if others have the opportunity to participate in a clinical trial to do it, because it worked for her, and it might just be the one that can work for them. “For people that are out there that think clinical trials don’t work, they do. I’m alive and well to say they do.”

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