“Z-endoxifen, a potent derivative of the drug tamoxifen, could itself be a new treatment for the most common form of breast cancer in women with metastatic disease. This finding was reported from a clinical trial conducted by researchers at Mayo Clinic and the National Cancer Institute, and published in the Journal of Clinical Oncology.
“The final results of a first-in-human phase I study of Z-endoxifen in women with estrogen receptor positive metastatic breast cancer showed that the treatment was safe and resulted in tumor shrinkage in women whose tumors had progressed on standard anti-estrogen therapies, including tamoxifen.”
“Previously the drug was approved as second-line monotherapy for women failing anti-estrogen therapy, and as second-line combination therapy with palbociclib (Ibrance). It was first approved by the FDA in 2002.”
“A duration of endocrine therapy beyond 5 years has gained traction in the treatment of endocrine receptor (ER)-positive early-stage breast cancer. Long-term use of aromatase inhibitors (AIs), however, may increase the risk of bone loss and bone fracture. Data suggest that the use of bone-targeted agents can substantially reduce the risk of osteoporotic complications associated with AI use, and even reduce the risk of bone recurrence in postmenopausal women with early-stage breast cancer.”
“The investigational third-generation nonsteroidal oral selective estrogen receptor degrader (SERD) RAD1901 was associated with a 23% objective response rate among 40 heavily pretreated women with estrogen receptor (ER)-positive, HER2-negative breast cancer, according to authors of a phase I dose-escalation and safety cohort study (NCT02338349) presented (abstract 1014) at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 2–6 in Chicago.”
“Endocrine therapy remains an integral part of the treatment paradigm for patients with estrogen receptor (ER)–positive breast cancer; however, questions remain on which patients should continue their therapy beyond 5 years.
” ‘The idea [is] that most patients with hormone receptor (HR)-positive breast cancer who are still on endocrine therapy at 5 years are going to merit some sort of discussion about whether they should continue or not, and it is okay to individualize that decision on the basis of the patient preferences, side effects, and symptom burden,’ said Amye J. Tevaarwerk, MD.”
“NanoString Technologies, Inc. (NASDAQ:NSTG), a provider of life science tools for translational research and molecular diagnostic products, today announced that Humana has issued a positive coverage decision for the Prosigna® Breast Cancer Gene Signature Assay. Humana and its more than 13 million members join other payors now covering Prosigna, collectively representing more than 175 million covered lives throughout the United States.
“This positive coverage decision is in line with updated ASCO guidelines released in February of 2016, wherein Prosigna is considered medically necessary to assess the necessity of adjuvant chemotherapy in ER-positive, HER2-negative, node-negative breast cancer patients, when adjuvant chemotherapy is not precluded due to any other factor.”
“Data from the phase II PERTAIN trial presented late last year at the 2016 San Antonio Breast Cancer Symposium (SABCS) showed that adding an aromatase inhibitor (AI) to pertuzumab (Perjeta) and trastuzumab (Herceptin) extended progression-free survival (PFS) by over 3 months versus trastuzumab plus an AI in patients with HER2-positive, HR-positive locally advanced or metastatic breast cancer.
“The median PFS was 18.89 months with the pertuzumab triplet compared with 15.80 months for trastuzumab and an AI alone (HR, 0.65; 95% CI, 0.48-0.89; P = .007). The objective response rates were 63.3% versus 55.7%, respectively.”
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…