Ligand Pharmaceuticals said its osteoporosis drug development partner Pfizer, Inc. has submitted a New Drug Application (NDA) with the US Food and Drug Administration (FDA) for Fablyn (lasofoxifene tartrate) Tablets (formerly, Oporia), a selective estrogen receptor modulator (SERM) for the treatment of osteoporosis in postmenopausal women.

Pfizer has included the three-year interim data from the Postmenopausal Evaluation And Risk-reduction with Lasofoxifene (PEARL) study in the current NDA to support its NDA for lasofoxifene in the treatment of osteoporosis.

"We are pleased that a Fablyn NDA has been submitted for the treatment of osteoporosis as the potential product provides an attractive treatment option for patients with osteoporosis," said John L. Higgins, president and chief executive officer, Ligand Pharmaceuticals. "Fablyn's progress is a clear representation of Ligand's expertise in the area of SERM discovery and research as well as Pfizer's commitment to this product."

The Ligand and Pfizer collaboration was formed to develop therapies for osteoporosis and subsequently produced lasofoxifene tartrate, an estrogen partial agonist for osteoporosis treatment and other diseases. Pfizer is responsible for the registration and worldwide marketing for Fablyn. Ligand is entitled to a milestone payment upon FDA approval, and would also receive royalty payments equal to 3 per cent of net sales.

In August 2004 Pfizer filed an NDA with the FDA for the use of Fablyn in the prevention of osteoporosis. An additional NDA was filed in December 2004 for the treatment of vaginal atrophy. Pfizer received "not-approvable" letters from the FDA for Fablyn for the prevention of post-menopausal osteoporosis in September 2005 and for the treatment of vaginal atrophy in January 2006.

Ligand discovers and develops new drugs that address critical unmet medical needs of patients in the areas of thrombocytopenia, hepatitis C, cancer, hormone-related diseases, osteoporosis and inflammatory diseases.