Radius has acquired exclusive worldwide rights, excluding Japan, to a new class of selective estrogen receptor modulators (SERMs) discovered by Eisai Co., Ltd. Radius is currently advancing its first development candidate from this class, RAD 1901, into pre-IND studies for the treatment and prevention of hot flashes (vasomotor symptoms) and osteoporosis. Financial terms were not disclosed.

SERMs bind and selectively activate the estrogen receptors of some tissues while blocking activation in other tissues. In bone, SERMs activate the estrogen receptors, improving bone mass. In breast and uterus tissues they prevent receptor activation and so can avoid the negative impact that prolonged estrogen therapy may have on these tissues. Yet raloxifene and other SERMs in development are not effective in reducing hot flashes and may exacerbate them. Preclinical studies conducted by Radius and Eisai suggest that RAD 1901 has the potential to reduce the hot flashes associated with menopause and to improve bone integrity, without stimulating breast or uterine tissues.

"RAD 1901 is possibly the first of a new class of SERMs that can both relieve hot flashes and prevent the bone loss caused by osteoporosis, without uterine and breast stimulation," said C. Richard Lyttle, PhD, President and Chief Executive Officer of Radius. "This compound could simultaneously address two critical unmet needs of postmenopausal women-control of hot flashes and prevention of osteoporosis."

"Eisai is very pleased to become a partner with Radius to develop RAD 1901 and contribute to this next-generation therapy for women's health," said K. Yoshimatsu, senior vice president of Research and Development of Eisai. "We discovered a novel SERM having activity on the central nervous system without peripheral estrogenic adverse effects. With Radius' expertise in endocrinology and osteoporosis, and Eisai's expertise marketing osteoporosis products in Japan, we see significant complementary strengths between our two companies that promise to make our partnership a significant success."

Hot flashes are a common symptom during menopause, with more than 75% of women experiencing them during the menopause transition, for a median duration of four years. These symptoms can disrupt sleep and interfere with quality of life. An estimated two million women undergo menopause every year in the U.S., with a total population of 50 million postmenopausal women. In addition, most women receiving systemic therapy for breast cancer suffer hot flashes, often with more severe or prolonged symptoms. Treatment with estrogen or hormone replacement therapy (ERT or HRT) is the standard of care for many women suffering hot flashes, but due to concerns about the potential long-term risks and contraindications, there is a significant need for new therapeutic options.

Osteoporosis is a leading cause of morbidity and mortality in elderly people worldwide. In the US alone, more than 44 million men and women have osteoporosis, or low bone-mineral density. A 50- year-old woman in the US has a 40 per cent risk of an osteoporotic fracture. Twenty percent of hipfracture patients enter long-term care, and half of this group never return to living independently.