June 15, 2023 – A drug that targets certain genes that help cancer cells thrive may, when combined with hormone therapy, help women with a certain style of early-stage breast cancer, latest research suggests.
The targeted therapy drug showed success in women with early-stage hormone receptor-positive/HER2-negative breast cancer, based on a study presented on the 2023 Annual Meeting of the American Society of Clinical Oncology (ASCO). The study showed that patients who received the drug ribociclib (Kisqali) together with standard hormone therapy remained symptom-free longer after their first cancer treatment than patients who received hormone therapy alone.
Also, Combining the drug with hormone therapy reduced the danger of cancer reoccurrence by 25%. Hormone receptor-positive/HER2-negative breast cancer accounts for about 65 to 70% of all breast cancer cases within the United States, making it probably the most common subtype.
“The goal of treatment for early-stage breast cancer is cure, with the hope that patients who receive curative therapy will not relapse,” said Dr. Dennis Slamon, director of clinical and translational research on the UCLA Comprehensive Cancer Center, who presented the outcomes on the meeting. “But we know that even at stage II, a third of these patients will relapse, and at stage III, more than half will relapse two or three decades later.”
Ribociclib is a drug called a CDK4/6 inhibitor, a drug designed to stop the expansion of cancer cells. The FDA approved it to treat HR-positive, HER2-negative advanced or metastatic breast cancer in premenopausal women, together with one other drug, an aromatase inhibitor, used to lower estrogen levels, or together with one other drug called fulvestrant in postmenopausal women.
The researchers randomly assigned about 5,000 individuals with HR-positive, HER2-negative stage IIA, IIB or III breast cancer who were susceptible to cancer reoccurrence to receive ribociclib together with hormone therapy (2,549 patients) or hormone therapy alone (2,552 patients).
Over time, 189 patients within the ribociclib group (7.4% of patients) experienced cancer reoccurrence, compared with 237 patients who received hormone therapy alone (9.2% of patients).
Patients were followed for about 34 months, with 20% completing 3 years of ribociclib treatment and 57% completing 2 years of treatment.
Cancer remission rates at 3 years were roughly 90% in patients receiving combination therapy, compared with just over 87% in patients treated with hormone therapy alone. The advantages observed within the ribociclib group were generally consistent across the opposite patient subgroups.
Ribociclib also showed higher results when it comes to overall survival and the length of time without signs or symptoms of cancer in the long run.
“Patients with [this type of cancer] “We now have a new treatment option,” said Dr. Sylvia Adams, medical oncologist and director of the Breast Cancer Center at New York University's Langone Perlmutter Cancer Center. “Adding ribociclib to endocrine therapy after surgery may reduce the risk of relapse and improve survival.”
Adams, who was not involved within the study, said there's one other CDK4/6 inhibitor, abemaciclib, that's FDA-approved to be used with hormone therapy. “Now we have a second option once ribociclib is approved for this indication and can decide with patients which of these two drugs to use based on their side effect profile and/or duration of treatment,” she said.
Slamon said overall survival was “trending in the right direction,” but longer follow-up was needed to see if ribociclib made a difference.