Pfizer could be just one step behind Wyeth in getting a new selective estrogen receptor modulator approved and on the market for the treatment of osteoporosis in postmenopausal women. The drug maker has submitted an NDA for Fablyn (lasofoxifene) in that indication, development partner Ligand announced Jan. 15.

The announcement could position Fablyn for approval in the second half of the year, given a standard 10-month review. Wyeth's NDA for its SERM Viviant (bazedoxifene) has a May 2008 user fee date for the treatment of postmenopausal osteoporosis.

Both drugs would have to compete against an already market-established SERM, Lilly's Evista (raloxifene), which is approved for both treatment and prevention of osteoporosis.

Pfizer received a "not approvable" letter from FDA for lasofoxifene (then Oporia ) for the prevention of postmenopausal osteoporosis in September 2005 (¹ Also see "Pfizer’s Oporia Is “Not Approvable” For Osteoporosis Prevention" - Pink Sheet, 13 September, 2005.). It was followed by another "not approvable" for the treatment of vaginal atrophy in January 2006.

The most recent NDA filing, for the treatment indication, includes three-year interim data from the Postmenopausal Evaluation And Risk-reduction with Lasofoxifene (PEARL) study. Pfizer has said the 8,500-person PEARL study could help reinforce the superiority of lasofoxifene over Evista.

Wyeth also has faltered in its quest to secure an osteoporosis-prevention indication for Viviant. The company received a second "approvable" letter for the claim in December, with FDA requesting further data on stroke and venous thrombotic events (² Also see "Wyeth’s Viviant Receives Second “Approvable” Letter For Osteoporosis Prevention" - Pink Sheet, 28 December, 2007.).

The first approvable came in April, with FDA requesting fracture data from a three-year pivotal trial (³ Also see "Wyeth’s Viviant “Approvable” For Prevention Of Postmenopausal Osteoporosis" - Pink Sheet, 24 April, 2007.).

- Jessica Merrill (j.merrill@elsevier.com)

Pfizer Files Lasofoxifene NDA For Treatment Of Osteoporosis

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