Merck & Co has signed a licensing deal to get access to Japan Tobacco’s JTT-305, an investigational oral bone-growth stimulating agent for osteoporosis.

Under the terms of the agreement, Merck is gaining worldwide rights, except for Japan, to develop and market JTT-305, an investigational oral calcium sensing receptor (CaSR) antagonist. Japan Tobacco will receive an undisclosed upfront payment and be eligible to get additional cash payments on the achievement of certain milestones. The Tokyo-based company would also be eligible for royalties (again undisclosed) from sales of any drug candidates that receive approval.

JTT-305 is currently in Phase II trials in Japan for its effect on increasing bone density and in Phase I studies outside the country. The firms noted that most current available osteoporosis therapies reduce fracture risk by slowing bone loss, while osteoanabolic drugs such as JTT-305, may reduce that risk by stimulating the growth of new bone and so increasing bone density.

Alan Ezekowitz, a senior vice president at Merck Research Laboratories, said that partnering with Japan Tobacco to develop the novel compound complements the firm’s portfolio of musculoskeletal drug candidates. In the future, “we believe that use of antiresorptive and osteoanabolic agents together may provide an effective way to reduce the risk of fractures in patients with osteoporosis,” he said.