Adding a New Drug to Standard Treatment May Add Years for Younger Women with Advanced Breast Cancer

Younger women battling advanced breast cancer may live longer by adding ribociclib to first-line endocrine therapy. That’s according to a study presented at the 2019 American Society of Clinical Oncology meeting.

Advanced breast cancer is the leading cause of death in women ages 20-59. Standard treatment involves hormonal treatments such as tamoxifen to block the effects of estrogen, or drugs called aromatase inhibitors to help stop estrogen production. Premenopausal women taking aromatase inhibitors need another drug as well, to shut down their ovaries. However, in women with advanced breast cancer, the hormonal therapy often stops working after a year or so.

This study looked at nearly 700 women with estrogen-sensitive tumors. The women ranged in age from 18-59, with 72% age 40 and older. All of the women had advanced breast cancer, which means it recurred after treatment or began to spread, and was no longer considered curable.

All of the women in the study received hormonal therapy and half were given ribociclib, a targeted therapy which blocks an enzyme called known as cyclin-dependent 4/6 kinases (CDK 4/6) that helps cancer grow. The researchers found that patients who took the drug along with standard therapy had a 70% survival rate after three and a half years compared to 46% for those who only received standard treatment.

Dr. Hatem Soliman

These findings only apply to women who have not yet reached menopause or are still going through it, and whose tumors are sensitive to estrogen but lack a protein called HER2.

"The cyclin dependent kinase 4/6 inhibitors like ribociclib have revolutionized the treatment of metastatic hormone receptor-positive breast cancer," said Moffitt Cancer Center’s Dr. Hatem Soliman. "It is exciting to see improved survival in younger women who often have more aggressive disease. We must continue to learn from these studies and develop personalized biomarkers so that we can select the optimal therapy for each patient."

Ribociclib was first approved by the Food and Drug Administration in 2017 for postmenopausal women with advanced breast cancer, and then in 2018 for younger women.