Human Genome Sciences Inc said its experimental lupus drug Benlysta was successful in a second large clinical trial, paving the way for approval of the first new treatment for the disease in 50 years.
Shares in Human Genome jumped 40 percent in pre-market trading.
The results from the latest clinical trial were not quite as convincing as those from an initial study, but still looked good enough to secure a green light from regulators and ensure doctors use the drug widely, industry analysts said on Monday.
The new trial showed patients given a high dose of Benlysta experienced a statistically significant improvement in symptoms compared with those taking a placebo.
Hopes for Benlysta have been growing since July, when it was shown to work in a first clinical trial -- to the surprise of many experts who had been skeptical, given the previously poor track record of new lupus treatments.
To win approval from regulators, Human Genome and its partner GlaxoSmithKline Plc needed to have a second successful study result. Glaxo shares were down 1.2 percent.
This is a pivotal moment in lupus research, said Margaret Dowd, president of the Lupus Research Institute, an organization that funds lupus research but did not fund Human Genome Science's trial.
It demonstrates the power of innovative science to drive discovery and achieve solid clinical results in the complex autoimmune disease of lupus.
Analyst Savvas Neophytou at brokerage Panmure Gordon said the companies had struck gold with the latest results and said registration of the drug would now be routine, adding the new blockbuster could be on the market well before the end of 2010.
Andrew Baum of Morgan Stanley, however, said the smaller benefit seen in the new trial might make it hard to achieve the expected high price of $20,000 to $30,000 per patient a year.
Glaxo and Human Genome, which will share profits from Benlysta on a 50-50 basis, said they planned to file for approval in the first half of next year.
$3 BILLION POTENTIAL
Assuming Benlysta now gets approved, Human Genome and Glaxo will have a drug worth as much as $3 billion a year, according to some analysts -- nice for Glaxo, the world's No. 2 drugmaker, and transformational for Human Genome, a small Rockville, Maryland-based company that has struggled in the shadows for years.
Data from a composite of three measures in the latest trial showed that after 52 weeks, 43.2 percent of patients taking 10 milligrams of Benlysta in combination with standard of care achieved an improvement in symptoms, with no significant worsening of disease in individual organs.
That compared with a figure of 33.8 percent for patients taking Benlysta in combination with a placebo.
The result met the main goal of the clinical trial.
Lupus causes the immune system to attack the body's own tissue and organs, including the joints, kidneys, heart, lungs, brain, blood and skin. It can cause arthritis, kidney damage, chest pain and skin rash, among other disorders.
Tammy Utset, an associate professor of medicine at the University of Chicago who was involved with the clinical studies said the results were spectacular news and should encourage further interest in drug development for lupus.
The trial also measured patients who took a low dose of the drug. The results of that part of the trial were not statistically significant.
Serious side effects were reported in 26.8 percent of patients taking Benlysta, compared with 24 percent of patients taking a placebo.
The trial, known as BLISS-76, is the second of two required by the U.S. Food and Drug Administration in order for the drug to be considered for approval.
The results follow similarly successful data from a trial known as BLISS-52 that were released in July. That trial showed 57.6 percent of patients taking a high dose of Benlysta in combination with standard of care showed an improvement in symptoms compared with 43.6 percent of patients taking standard of care plus a placebo.
Lupus affects about 1.5 million people in the United States and 5 million worldwide, according to the Lupus Foundation of America.
(Editing by Hans Peters and David Holmes)