“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.”
“About one in five patients with post-chemotherapy metastatic breast cancer attained an objective response to single-agent therapy with the cyclin-dependent kinase (CDK)4/6 inhibitor abemaciclib, results of a phase II trial showed.
“Responses were durable, lasting an average of almost 9 months, and more than 40% of patients obtained clinical benefit. Abemaciclib’s safety and tolerability were consistent with previous clinical experience, as no new or unexpected adverse events occurred among 132 patients who received the drug.”
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…
“G1 Therapeutics, Inc., a clinical-stage oncology company, announced today the expansion of its pipeline of novel cancer therapies with the initiation of three development programs in breast cancer. G1 is enrolling a Phase 2 study of its intravenous CDK4/6 inhibitor trilaciclib for the treatment of triple-negative breast cancer (TNBC), and a Phase 1b/2a study of its oral CDK4/6 inhibitor G1T38 for the treatment of estrogen receptor-positive, HER2-negative (ER+, HER2-) breast cancer. In addition, G1 is advancing G1T48, its oral selective estrogen receptor degrader (SERD) with the goal of commencing a Phase 1 trial in the fourth quarter of 2017.”
“The addition of a targeted agent to endocrine therapy for metastatic breast cancer led to unprecedented improvement in progression-free survival (PFS) that will have a ‘paradigm changing’ effect on clinical management, an investigator said here.
“Patients who received the cyclin-dependent kinase (CDK)4/6 inhibitor ribociclib in addition to letrozole (Femara) had a 44% reduction in the PFS hazard compared with patients treated with letrozole alone. The median PFS (primary endpoint) was 14.7 months with letrozole but had yet to be reached with letrozole plus ribociclib, ‘but it is expected to far exceed what the control arm did,’ Gabriel N. Hortobagyi, MD, reported at the European Society for Medical Oncology (ESMO) conference.”