UPDATE 2-FDA denies approval for Human Genome's anthrax drug

* Gets complete response letter for raxibacumab BLA

* Says FDA requested additional information

* Says plans to address the current questions

* Shares flat (Adds analyst comments, background; updates stock movement)

By Krishnakali Sengupta

BANGALORE, Nov 16 (Reuters) - Human Genome Sciences Inc HGSI.O said the U.S. health regulators declined to approve its experimental treatment for anthrax infection.

The company said the U.S. Food and Drug Administration (FDA) issued a complete response letter asking for additional information relating to its biologics license application (BLA) seeking approval of ABthrax, also known as raxibacumab.

Summer Street Research analyst Carol Werther said the news was not surprising as last month a U.S. advisory panel suggested more studies to show that the treatment adds benefit beyond antibiotics alone. [ID:nN26191223]

The FDA had also raised questions about tests used to measure the drug’s absorption in people, making it impossible to judge if the product was fit for approval.

The company said in a statement that the complete response letter sent by the FDA seemed ‘inconsistent’ with the agency’s published final rule governing the development of new drugs.

“We have responded to all of FDA’s previous questions. We plan to address the current questions as well,” Sally Bolmer, the company’s senior vice president of development and regulatory affairs, said in a statement.

ABthrax was developed under a government project to encourage new drugs and vaccines to fight potential bioweapons. The project was launched after letters carrying powdered anthrax killed five people in 2001.

The U.S. government had already ordered 65,000 doses of ABthrax for a national stockpile of emergency medicines. In July, the company received more than $160 million through sales of the drug to the government in the first two quarters of 2009.

The company is due to receive additional $10 million if ABthrax wins the FDA approval.

Earlier this month, Human Genome stock had shot up more than 30 percent after its experimental lupus drug Benlysta eased symptoms in more than 43 percent of patients who took it in a clinical trial. [ID:nN30423138]

Analyst Werther said people are more interested in Benlysta which looks like approvable and should be filed in the first quarter of 2010.

“Opportunity for Benlysta could be $2 billion, while ABthrax is only a smaller part of the story. Thus today’s news will have only minimal impact on the stock”.

Shares of the company were down 2 cents at $27.91 in late morning trade Monday on Nasdaq. (Reporting by Krishnakali Sengupta in Bangalore; Editing by Pradeep Kurup)