New CDK4/6 Inhibitor Offers Benefits for Advanced-Stage, Hormone Receptor-Positive, HER2-Negative Breast Cancer

New CDK4/6 Inhibitor Offers Benefits for Advanced-Stage, Hormone Receptor-Positive, HER2-Negative Breast Cancer

When given as a first treatment, the combination of dalpiciclib — a new CDK4/6 inhibitor — with either Arimidex or Femara improved progression-free survival in women diagnosed with advanced-stage, hormone receptor-positive, HER2-negative breast cancer.
Sep 14, 2022.
 

When given as a first treatment, the combination of dalpiciclib, a new CDK4/6 inhibitor, with an aromatase inhibitor — either Arimidex (chemical name: anastrozole) or Femara (chemical name: letrozole) — improved progression-free survival in women diagnosed with advanced-stage, hormone receptor-positive, HER2-negative breast cancer, according to a Chinese study.

The research was presented at the European Society for Medical Oncology (ESMO) Congress 2022 on Sept. 9, 2022.

Progression-free survival is how long people live without the cancer growing.

Advanced-stage breast cancer is either locally advanced breast cancer or metastatic breast cancer. Locally advanced breast cancer is breast cancer that has spread to tissue near the breast, but not to parts of the body away from the breast. Metastatic breast cancer is breast cancer that has spread to parts of the body away from the breast, such as the bones or liver.

 

About dalpiciclib

Dalpiciclib is a CDK4/6 inhibitor, a relatively new type of targeted therapy medicine. CDK4/6 inhibitors target proteins known as the cyclin-dependent kinases 4 and 6, abbreviated as CDK4/6.

The CDK4/6 proteins, found both in healthy cells and cancer cells, control how quickly cells grow and divide. CDK4/6 inhibitors interrupt these proteins to slow or even stop cancer cells from growing.

Dalpiciclib, a pill taken by mouth, is not approved by the U.S. Food and Drug Administration (FDA) at this time. There are three other CDK4/6 inhibitors used to treat breast cancer in the United States:

  • Ibrance (chemical name: palbociclib)

  • Kisqali (chemical name: ribociclib)

  • Verzenio (chemical name: abemaciclib)

 

About the study

Called the DAWNA-1 trial, the study included 456 women diagnosed with advanced-stage, hormone receptor-positive, HER2-negative breast cancer. The women were both pre- and post-menopausal and ranged in age from 47 to 63 years.

None of the women had received any treatments for advanced-stage breast cancer when they joined the study.

The researchers randomly split the women into two treatment groups:

  • 303 women received dalpiciclib plus either Arimidex or Femara

  • 153 women received either Arimidex or Femara, plus a placebo pill that looked just like dalpiciclib but contained no medicine

The researchers followed half the women for more than 21 months and the other half for shorter periods of time.

Women who received dalpiciclib plus an aromatase inhibitor had longer progression-free survival than women who received only an aromatase inhibitor. Progression-free survival was:

  • 30.6 months for women who received dalpiciclib plus an aromatase inhibitor

  • 18.2 months for women who received only an aromatase inhibitor

This difference was statistically significant, which means it was likely due to the difference in treatment and not just because of chance.

“The progression-free survival benefit with dalpiciclib was evident regardless of menopausal status,” said Binghe Xu, MD, PhD, of the Chinese Academy of Medical Sciences and Peking Union Medical College in China, who presented the results.

 

Dalpiciclib side effects

The most common side effects in women who received dalpiciclib and an aromatase inhibitor were:

  • low white blood cell counts

  • low red blood cell counts (anemia)

  • low platelet levels (thrombocytopenia)

Grade 3, grade 4, and serious side effects were more common in women who received dalpiciclib and an aromatase inhibitor than in women who received only an aromatase inhibitor:

  • 90.4% of women who received dalpiciclib had a grade 3 or grade 4 side effect

  • 12.4% of women who received only an aromatase inhibitor had a grade 3 or grade 4 side effect

  • 11.9% of women who received dalpiciclib had a serious side effect

  • 6.5% of women who received only an aromatase inhibitor had a serious side effect

  • 4% of the women who received dalpiciclib stopped treatment because of side effects

  • 2% of women who received only an aromatase inhibitor stopped treatment because of side effects

“These findings support dalpiciclib plus letrozole or anastrozole as a new first-line treatment option in patients with untreated [hormone receptor-positive, HER2-negative advanced breast cancer,” said Dr. Xu.

 

What this means for you

If you’ve been diagnosed with advanced-stage, hormone receptor-positive, HER2-negative breast cancer and are deciding on first treatments with your doctor, the results of this study may be promising.

But it’s important to remember that dalpiciclib is not approved to be used in the United States unless it’s being used in a clinical trial.

And it’s also important to know there are three other CDK4/6 inhibitors that are available in the United States, so you have treatment options.

Still, some of the CDK4/6 inhibitors available in the United States may not be as readily available in certain parts of China.

“The progression-free survival results suggest extension of dalpiciclib approval to the first-line metastatic breast cancer setting in the Chinese population,” Meritxell Bellet, MD, PhD, medical oncologist at the Vall d’Hebron Institute of Oncology in Barcelona, Spain, said in her discussion of the results.

Learn more about CDK4/6 inhibitors.

Written by: Jamie DePolo, senior editor

— Last updated on September 23, 2022, 6:46 PM

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