fizer’s bid to get approval for its investigational osteoporosis compound lasofoxifene, to be sold as Fablyn, has been thwarted yet again by regulators in the USA.

The New York-based firm released a short statement saying it has received a complete response letter from the US Food and Drug Administration asking for additional information on the company’s application for lasofoxifene. Pfizer limited itself to saying that it is reviewing the letter “and will work with FDA to determine the appropriate next steps regarding the company’s application”.

This latest development comes just a few months after the FDA’s Advisory Committee for Reproductive Health Drugs voted, somewhat surprisingly, 9-3 that the benefits of once-daily Fablyn, a selective estrogen receptor modulator, outweigh the risks. That vote follows briefing documents from FDA staffers who noted that patients who took the lowest dose of the drug (0.25mg), which is developed using technology from Ligand Pharmaceuticals, had a higher incidence of blood clots and deaths compared with the group on placebo.

In 2005, the FDA rejected an application for the drug - then called Oporia - for prevention of osteoporosis and in 2006 turned down a second indication of vaginal atrophy. Both of those not approvable letters highlighted concerns about an increased risk of endometrial cancer, but Pfizer resubmitted the drug with new data from a five-year study involving more than 9,000 women.

Pfizer will be hoping the drug fares better in the hands of regulators across the Atlantic. The Committee for Medicinal Products for Human Use of the European Medicines Agency issued a positive opinion on lasofoxifene, which belongs to the same drug class as Eli Lilly’s Evista (raloxifene) in December.

Meantime, the Wall Street Journal is reporting that Pfizer is looking to lay off as many as 2,400 sales staff this quarter, which would represent about one-third of the company's marketing workforce.
Pfizer, which has already cut about 15,000 jobs in the last couple of years, including 800 research jobs in the last week, made no comment on the story.