FDA Rejects Amgen’s Prostate Cancer Drug

The Food and Drug Administration rejected as “inadequate” a prostate cancer treatment from Amgen Inc. and Praecis Pharmaceuticals Inc., the companies said Tuesday.

The drug makers wouldn’t elaborate on the reasons for the denial but said they hoped to meet with the FDA soon to “clarify various deficiencies . . . and to discuss what further steps need to be taken.”

Analysts said Tuesday they believed the drug, known as Plenaxis, eventually would be approved.

Analysts hadn’t expected the drug to be a big moneymaker for Amgen, which has three other medications in its approval pipeline. The most critical of those is Aranesp, a longer-lasting version of its blockbuster anemia treatment, Epogen, which had sales of $2 billion last year.

Amgen expects an FDA decision soon on Aranesp, which the European Union approved Monday.

Analysts had expected Plenaxis sales of $10 million to $20 million this year, with estimates as high as $175 million in 2002. Many analysts significantly reduced those forecasts Tuesday.

Lehman Bros. analyst Joseph Dougherty, for example, slashed his sales estimate to $60 million from $100 million in 2002. He said lower sales would have little effect on Amgen, which had sales of $3.2 billion last year. The delay is more significant to Praecis, a biotechnology start-up with no products.

Shares of Waltham, Mass.-based Praecis tumbled $6.04 to close at $16.55. Shares of Thousand Oaks-based Amgen closed at $66.92, up 17 cents. Both trade on Nasdaq.

Plenaxis belongs to an emerging class of drugs that suppress testosterone levels during the early phase of treatment. Existing drugs, such as Lupron and Zoladex, cause testosterone levels to spike before bringing them lower. Testosterone plays a role in prostate cancer.

Lupron is marketed by TAP Pharmaceuticals, a joint venture of Abbott Laboratories and Takeda Chemical of Japan. It is expected to have sales of $800 million this year. Zoladex is made by Astra Zeneca.

Analysts speculated that Plenaxis may face a number of hurdles at the FDA.

Craig West of A.G. Edwards & Sons in St. Louis said that the class of drugs to which Plenaxis belongs is known to stimulate production of histamine, the protein that causes such allergic reactions as watery eyes and sneezing.

In addition, he said, lower levels of testosterone are associated with reductions in bone density, though that is a drawback of existing prostate cancer treatments as well.

Dougherty of Lehman Bros. said the FDA may feel little urgency to approve Plenaxis when two effective medications are available. The FDA has moved more deliberately in wake of a series of drug recalls last year, he said.

“It is a sign of what we’ve seen more broadly . . . that it is taking longer for drugs to get approved. There is more caution at the FDA.”