Shares of Human Genome Sciences doubled in Thursday morning trading on news that a major British biopharmaceutical company offered to buy it for $2.6 billion, which the Rockville company rejected as too low.

Human Genome, which uses the human DNA sequence to develop targeted drugs, said in a news statement that GlaxoSmithKline PLC offered to buy the company for $13 a share in cash. The company declined the offer, saying it did not "reflect the value inherent" in Human Genome, and added that it had begun exploring strategic alternatives, including a possible sale.


Human Genome's shares doubled to more than $14 when the Nasdaq stock exchange opened Thursday morning. It closed at $14.17.

Human Genome said it invited GlaxoSmithKline to participate in its strategic review process as it considers its options.

Human Genome and GlaxoSmithKline have worked together on drug development. Last year, the Food and Drug Administration approved the sale of Benlysta, a drug for the treatment of lupus. The two companies had collaborated on the drug's development since 2006.

Human Genome is also working on drugs that treat inhalation anthrax, cardiovascular disease, Type II diabetes and cancer. The company said it also has financial rights to several drugs that are in development by GlaxoSmithKline.

In its last quarter, Human Genome reported revenues of $45 million and a loss of $81 million. The company has posted losses for several years. Many bio pharmaceutical companies post years of losses as drug development expenses are typically high, and it can take a decade or more before a new drug gets approved and is ready for sale.

Human Genome was founded in 1992 and has about 1,000 employees.