Breast Cancer

Significantly improved survival for pre-menopausal women with Advanced BC

Leading Opinions Digital, 03.06.2019

Overall survival data of Phase III MONALEESA-7 trial of premenopausal patients with HR+/HER2− advanced breast cancer (ABC) treated with endocrine therapy ± ribociclib were presented on ASCO Annual Meeing 2019.Women who got ribociclib lived a median of 23.8 months without their disease progressing compared with 13 months for women who received a placebo.

The international, randomized phase III MONALEESA-7 trial found that adding ribociclib to standard-of-care endocrine therapy significantly improved overall survival for premenopausal women with advanced HR-positive/HER2-negative breast cancer compared with endocrine therapy alone. After 42 months of follow-up, the survival rate was 70% for women who took the combination therapy compared with 46% for women who received endocrine therapy only. “This is the first study to show improved survival for any targeted therapy when used with endocrine therapy as a firstline treatment for advanced breast cancer,” said lead study author Sara A. Hurvitz, MD, Director of the Breast Cancer Clinical Research Program at UCLA Jonsson Comprehensive Cancer Center in Los Angeles, CA. “The use of ribociclib as a front-line therapy significantly prolonged overall survival, which is good news for women with this terrible disease.”

About the Study
MONALEESA-7 is the first trial to focus exclusively on women under age 59 who were premenopausal and had advanced breast cancer for which they had not received prior endocrine therapy. Investigators randomly assigned women to ribociclib (a tablet), or to a placebo tablet. All women also received goserelin, an injectable endocrine therapy that suppresses estrogen, and one of three other therapies: the nonsteroidal aromatase inhibitors letrozole (Femara) or anastrozole (Arimidex), which lower estrogen production, or tamoxifen, which has beenused to treat breast cancer for over 40 years and blocks the effects of estrogen in breast tissue.Six hundred and seventy-two women were enrolled in the study. After a median follow-up of 34.6 months, 173 (26%) were still receiving the therapies, with 116 (35%) of the women still receiving ribociclib and 57 (17%) still receiving the placebo.

Key Findings
The women who received ribociclib lived a median of 23.8 months without the disease progressing compared with 13 months for women who received the placebo.4 The researchers observed that after 42 months of follow-up, for patientsreceiving ribocilcib, the survival rate was 70% when given with endocrine therapy compared with 46% when given with placebo. Overall this represented a 29% relative reduction in the risk of death. In addition, the survival rate of 71% and 70% for women who took ribociclib in combination with tamoxifen or a nonsteroidal aromatase inhibitor, respectively, compared with a survival rate of 55% and 43%, respectively, for women who received placebo in combination with tamoxifen or aromatase inhibitors only.

Next Steps
The researchers are doing analyses of patient-reported outcomes as well as sub-analyses of the clinical findings, including looking at biomarkers and circulating tumor DNA that may help them determine which women might benefit most from ribociclib. The investigators are studying the use of ribociclib in women and men with early-stage HR+, HER2-negative breast cancer in combination with endocrine therapy and other cancer indications.