Pfizer ( PFE) said the Food and Drug Administration rejected its application for Oporia, an experimental treatment for osteoporosis.

In a terse, two-sentence announcement, Pfizer said it will discuss its application with the agency and consider "various possible courses of action." The FDA's rejection of Oporia, known by its scientific name lasofoxifene, was a setback for a drug that Pfizer had hoped would have multiple uses.

Pfizer filed its osteoporosis application with the agency 13 months ago. In December, it asked the FDA to approve the drug as a treatment for vaginal atrophy. A Pfizer spokeswoman said the FDA hasn't commented on the vaginal atrophy application.

The news helped send Pfizer's stock down 33 cents, or 1.3%, to $26.01 in early afternoon trading. Shares of Pfizer's partner, Ligand Pharmaceuticals, ( LGND) fell 79 cents, or 9%, to $8.01.

Pfizer's collaboration with Ligand, which now trades as a "pink sheet" stock, calls for Ligand to receive certain royalty payments during the drug's development. Ligand will get other payments if the drug is approved, and it will receive additional royalties equal to 6% of worldwide sales for any approved use of the drug.

San Diego-based Ligand, which has development deals with several Big Pharma companies, said Monday night that it's now the subject of a formal investigation by the Securities and Exchange Commission regarding the companies restatement of earnings for 2002 and 2003, each quarter of 2003 and the first three quarters of 2004.

"These matters have been the subject of an informal SEC inquiry," Ligand said in a press release issued Monday about six hours after markets had closed. "Ligand has been fully cooperating with the SEC and will continue to do so."

Ligand was delisted from Nasdaq last week. The company is seeking reinstatement, saying that it hopes to be in compliance with all SEC financial report-filing guidelines within 60 days.

The company's stock was delisted because Ligand failed to make timely filing of its financial reports to the SEC. Ligand says the filing of its 2004 10-K statement and its filing of 10-Q reports for the first two quarters of 2005 have been delayed while other financial reports are being restated.

Separately, Pfizer said European health regulators approved a new use for Aromasin, a breast cancer drug that was approved in Europe and in the U.S. in 1999. Aromasin is a hormonal therapy for women whose breast cancers depend on the hormone estrogen.

The drug has been available to European women as a treatment following surgical removal of the first breast cancer tumor that occurs before the cancer has spread to other parts of the body. The new approval in Europe allows Aromasin to treat early breast cancer following two to three years of initial therapy with another breast cancer drug, tamoxifen, in postmenopausal women.

Pfizer says clinical trials show that women who switched to Aromasin had a "31% better probability of disease-free survival" than women who remain on tamoxifen, which is sold under the brand name Nolvadex by AstraZeneca ( AZN).

In the U.S., Aromasin is approved for treating advanced breast cancer in postmenopausal women whose cancer has grown following tamoxifen therapy.