-Elacestrant 400mg single agent Objective Response Rate (ORR) was 27.3% in heavily pre-treated patients with advanced ER+ breast cancer at the pre-determined study cutoff date of October 30, 2017-

-Median PFS was 5.4 months and Clinical Benefit Rate at 24 weeks was 47.4% –

-38% of study patients previously received fulvestrant; 40% received palbociclib or other CDK 4/6 inhibitor; 50% had an ESR1 mutation-

-10 of the 40 patients remain on treatment as of the cutoff date-

WALTHAM, MA, USA I December 07, 2017 I Radius Health, Inc. (Nasdaq:RDUS) today provided an update on data from the Phase 1 005 clinical study of elacestrant (RAD1901), an oral selective estrogen receptor degrader (SERD), in patients with estrogen receptor positive (ER+) breast cancer. The data were presented at a Spotlight Presentation (Abstract 1410) during the 2017 San Antonio Breast Cancer Symposium (SABCS). Elacestrant recently received Fast Track designation from the U.S. Food and Drug Administration.

There are 40 patients that have been treated at the 400 mg dose in the elacestrant Phase I dose escalation and expansion cohorts. All study participants are heavily pretreated ER+, HER2-negative, advanced breast cancer patients that have received a median of three prior lines of systemic therapy and have evaluable advanced or metastatic disease. Of the enrolled patients, 22 patients met the RECIST measurable disease criteria at baseline and there were 6 confirmed partial responses in this group. Elacestrant was well-tolerated with the most common adverse events being low grade nausea, dyspepsia and vomiting.

“It is quite encouraging to see the clinical activity with elacestrant in the heavily pretreated advanced patient population, and further therapeutic development is warranted for patients with hormone receptor positive breast cancer”, commented Dr. Aditya Bardia, Director of Precision Medicine and attending physician at Center for Breast Cancer, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA. 

Radius plans to initiate a Phase 2 clinical study of elacestrant monotherapy, a potentially pivotal study, for women with advanced or metastatic ER+/HER2- breast cancer early in 2018. 

“Patients cycle through and generally do not repeat treatment regimens, limiting treatment options as their disease advances. We are pleased about the potential to offer patients who have progressed or relapsed during their current standard of care with a new treatment option,” said Gary Hattersley, PhD, Chief Scientific Officer. “Radius is committed to developing and to providing breast cancer patients with the next generation of hormonal treatment options, as a single agent and in combination, across all lines of therapy.”   

An update on data from the elacestrant FES PET 106 Phase I clinical study in the EU was presented yesterday and demonstrated that elacestrant reduces 18F-FES uptake in patients with advanced ER+ breast cancer who progressed on prior endocrine therapy. The reduction in FES uptake supports elacestrant dose selection for further clinical development and was similar in patients harboring mutant or wildtype ESR-1. Three preclinical poster presentations further highlighting and demonstrating elacestrant activity, as a single agent and in combination with other targeted therapies, will be presented tomorrow morning at SABCS.

Following a strategic review, Radius has decided to discontinue further evaluation of elacestrant for vasomotor symptoms and will focus instead on the continued clinical development of the compound as a potential treatment option in breast cancer.

About Elacestrant (RAD1901)
Elacestrant is a selective estrogen receptor degrader (SERD), which is being evaluated for potential use as a once daily oral treatment for hormone-receptor positive breast cancer. Elacestrant is currently being investigated for potential use in women with advanced estrogen receptor positive, HER2 negative, breast cancer, the most common form of the disease. Studies completed to date indicate that the compound has the potential for use as a single agent or in combination with other therapies for the treatment of breast cancer.

Additional information on the clinical trial program of elacestrant (RAD1901) is available on www.clinicaltrials.gov.

About Radius

Radius is a science-driven fully integrated biopharmaceutical company that is committed to developing and commercializing innovative therapeutics in the areas of osteoporosis, oncology and endocrine diseases. Radius’ lead product, TYMLOS (abaloparatide) injection, was approved by the U.S. Food and Drug Administration for the treatment of postmenopausal women with osteoporosis at high risk for fracture. Radius’ Marketing Authorisation Application (MAA) for abaloparatide-SC for the treatment of postmenopausal women with osteoporosis is under regulatory review in Europe. The Radius clinical pipeline includes an investigational abaloparatide transdermal patch for potential use in osteoporosis; the investigational drug elacestrant (RAD1901) for potential use in hormone-receptor positive breast cancer; and the investigational drug RAD140, a non-steroidal, selective androgen receptor modulator (SARM) under investigation for potential use in hormone-receptor positive breast cancer. For more information, please visit www.radiuspharm.com.

SOURCE: Radius Health