“The first-ever direct comparison of three adjuvant aromatase inhibitors for the treatment of postmenopausal hormone receptor–positive early breast cancer shows no significant differences in clinical efficacy or safety, according to an Italian research team.
“In the randomized, open-label phase 3 FATA-GIM3 trial of almost 3700 women, the 5-year disease-free survival for patients treated with anastrozole (Arimidex, Novartis), exemestane (Aromasin, Pfizer), or letrozole (Femara, Novartis) was 90.0%, 88.0% and 89.4%, respectively.”
“The progression-free survival (PFS) benefit for ribociclib (Kisqali) in pre- or perimenopausal women with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer was sustained across patient subgroups, according to findings from the phase III MONALEESA-7 trial presented at the 2018 Miami Breast Cancer Conference.
“MONALEESA-7 randomized patients to either the CDK4/6 inhibitor ribociclib in combination with tamoxifen or a nonsteroidal aromatase inhibitor (NSAI; letrozole or anastrozole) plus goserelin (n = 335), or to endocrine treatment plus goserelin (n = 337). Across the overall study population, the median PFS was 23.8 months for the ribociclib arm compared with 13.0 months for the control arm (HR, 0.553; 95% CI, 0.441-0.694; P <.0001).”
“Pfizer Inc. (NYSE:PFE) today announced updated progression-free survival (PFS) results from the Phase 3 PALOMA-2 trial reinforcing the clinical benefit of IBRANCE® (palbociclib) combined with letrozole. The data, which will be presented at the 2017 San Antonio Breast Cancer Symposium (SABCS) on December 8 [abstract #P5-21-03], demonstrate that the combination of IBRANCE plus letrozole reduced the risk of disease progression by 44 percent and improved median PFS by more than one year compared to letrozole plus placebo (27.6 months [95% CI: 22.4, 30.3] vs 14.5 months [95% CI: 12.3, 17.1]) when used as the initial treatment for postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+, HER2-) metastatic breast cancer (HR=0.56 [95% CI: 0.46, 0.69]). This updated, post-hoc analysis included a median follow-up of more than three years, which is the longest to date of any Phase 3 study of a CDK 4/6 inhibitor.”
“An intermittent dosing schedule with extended adjuvant letrozole did not improve disease-free survival (DFS) over continuous treatment with the agent in postmenopausal women with hormone receptor–positive breast cancer, according to the randomized phase III SOLE trial.
” ‘The magnitude of the beneficial effect of 5 years of extended letrozole use in postmenopausal women who have previously received an aromatase inhibitor for 5 years is low,’ wrote study authors led by Marco Colleoni, MD, of the European Institute of Oncology in Milan, Italy. That small effect may be partially due to acquired resistance, and animal studies suggest that such resistance can be reversed by discontinuing treatment.”
“Adding taselisib to letrozole before surgery significantly improved outcomes for patients with early breast cancer that was both estrogen receptor positive and HER2-negative (ER+/HER2-) according to results of the LORELEI trial, presented at the ESMO 2017 Congress in Madrid.
” ‘We were able to detect a reduction in tumor size after only 16 weeks of treatment, compared to patients who received letrozole plus placebo,’ said study investigator Dr. Cristina Saura, from Vall d’Hebron University Hospital in Barcelona, Spain. ‘Any decrease in tumor measurements is something positive for patients because this means the drug has had activity against their tumor in a short period of time.’ ”
“The FDA has approved co-packaging of the oral medications ribociclib (Kisqali) and letrozole (Femara) for the treatment of postmenopausal women with HR-positive, HER2-negative advanced breast cancer.
“With the new Kisqali Femara Co-Pack, patients can obtain a full 28-day cycle of the 2 medicines in 1 package with 1 prescription and 1 copay, and the cost will be the same as that for Kisqali alone, according to Novartis, which manufactures both medications.”
“Adding abemaciclib to letrozole or anastrozole improved progression-free survival (PFS) compared with either aromatase inhibitor alone in women with HR+/HER2-negative breast cancer enrolled in the phase III MONARCH 3 study, according to Eli Lilly and Company, the manufacturer of the CDK4/6 inhibitor.
“MONARCH 3 (NCT02246621) is the second phase III trial of abemaciclib to demonstrate improved PFS in patients with HR+/HER2-negative breast cancer. In March, Lilly announced that in the MONARCH 2 study, combining abemaciclib with fulvestrant extended PFS compared with fulvestrant alone in patients who had progressed during or within 1 year of receiving endocrine therapy in the neoadjuvant or adjuvant setting, or during frontline endocrine treatment for metastatic disease.”
“The US Food and Drug Administration (FDA) has approved Kisqali®(ribociclib, formerly known as LEE011) in combination with an aromatase inhibitor as initial endocrine-based therapy for treatment of postmenopausal women with hormone receptor positive, human epidermal growth factor receptor-2 negative (HR+/HER2-) advanced or metastatic breast cancer.
“Kisqali is a CDK4/6 inhibitor approved based on a first-line Phase III trial that met its primary endpoint early, demonstrating statistically significant improvement in progression-free survival (PFS) compared to letrozole alone at the first pre-planned interim analysis. Kisqali was reviewed and approved under the FDA Breakthrough Therapy designation and Priority Review programs.”
Doctors prescribe drugs known as CDK inhibitors to treat some women with estrogen-receptor-positive (ER+) metastatic breast cancer. Research into these drugs is ongoing, and new, promising CDK inhibitor options are on the horizon. Here, I address the current outlook for CDK inhibitors in ER+ breast cancer.
First, some background: ER+ breast cancers comprise about 70% of all breast cancers. The name reflects the fact that cells of these cancers express estrogen receptors (ERs), which are protein features targeted by many treatment strategies for this cancer type. The estrogen receptor (ER) protein is a treatment target not only because “it is there,” but mainly because it drives tumor cell proliferation in ER+ breast cancer. The activity of the ER depends on its binding to the hormone estrogen, and treatments known as endocrine drugs aim to prevent this interaction. Some endocrine drugs inhibit the synthesis of estrogen in the body (e.g., aromatase inhibitors, such as letrozole and anastrozole), and others prevent the interaction of estrogen with ERs (e.g., ER modulators such as tamoxifen, or the pure anti-estrogen drug fulvestrant). The problem of course is that, in metastatic breast cancer, resistance develops to each and every endocrine drug used. Continue reading…