Biogen Idec. Inc. has halted development of an experimental drug to treat the devastating neurodegenerative disorder known as Lou Gehrig’s disease, saying Thursday that it proved ineffective in a late-stage clinical trial.
The decision deals a blow to an estimated 30,000 Americans who suffer from amyotrophic lateral sclerosis, or ALS, a fatal condition for which there is no cure.
“There were a lot of people hanging onto this as their hope, just wishing for something.” said Marilyn Sanford of Tewksbury, who was diagnosed with ALS in 2008 and has spoken with Biogen Idec scientists about living with the disease.
It was also a setback for Weston-based Biogen Idec and its chief executive, George A. Scangos, who had bet more than $80 million on the high-risk ALS program in 2010 when he licensed dexpramipexole — the compound used in the drug — from Knopp Biosciences LLC, of Pittsburgh.
“This is heartbreaking for us and especially for the team that was involved,” said Dr. Gilmore N. O’Neill, a neurologist who is vice president of clinical development at Biogen Idec. “Many of us have been working for years with patients and families as they face this disease.”
Lou Gehrig’s disease gained wide attention in Massachusetts in 2011 when a former governor, Paul Cellucci, 64, disclosed he had been diagnosed with ALS two years earlier.
Typically, ALS symptoms appear after age 50.
While most drug candidates fail, dexpramipexole made it to a Phase 3 clinical trial — typically the final step before drug companies seek approval from the Food and Drug Administration to market a treatment. That raised ALS patients’ expectations.
“Getting this to a Phase 3 trial was a big deal,” said Lynn Aaronson, executive director of the Massachusetts chapter of the ALS Association, a nonprofit working to find an ALS cure. “We were all just stunned today. The news came out of left field for us.”
The experimental treatment had earlier shown “a hint” of effectiveness in a smaller mid-stage clinical study, O’Neill said, but there was “an absence of observable benefits in function or survival for ALS patients or any subgroup” in Biogen Idec’s larger Phase 3 trial.
That testing involved 942 patients at 81 sites around the world over 18 months. Some were given the Biogen Idec drug, while others received placebos.
O’Neill said Biogen Idec remains committed to advancing treatments for ALS, both in its own preclinical programs and through alliances with Harvard University, the University of Massachusetts, and other biotechnology and academic researchers worldwide. Biogen Idec’s study will help physicians diagnose the disease sooner and better understand its progression, he said.
ALS, which affects about five out of every 100,000 people globally, prevents nerve cells from sending messages to muscles, leading to muscle weakening, twitching and, eventually, paralysis.
As the condition worsens, patients find it difficult to breathe. Most die within three to five years after they are diagnosed.
Riluzole, the only ALS medicine approved by the FDA, can slow symptoms, helping patients to live longer. All of the ALS patients taking part in the dexpramipexole clinical trial were also taking riluzole.
“We’re saddened by the news,” Carrie Martin Munk, a national spokeswoman for the ALS Association in Washington, D.C., said of the trial’s failure.
“It has to be disappointing to the thousands of people with ALS and their families. When you’re dealing with a disease like ALS, and you have only one FDA-approved drug, hope is really centered on all of the potential therapies.”
Shares of Biogen Idec, which tumbled nearly 6 percent in premarket trading Thursday morning, rebounded to close down 1.4 percent at $147.86, losing $2.14.
Some industry analysts said they had not built the drug candidate into their revenue projections for the company because of the nature of ALS research and development.
“ALS trials are considered risky due to high patient variability and significant number of past clinical failures,” Robyn Karnauskas, a biotechnology analyst for Deutsche Bank in New York, wrote in a note to investors.
Karnauskas said she was more focused on Biogen Idec’s potential multiple sclerosis treatments, including the promising BG-12 pill. Biogen Idec is awaiting an FDA ruling during the first half of this year on its application to start selling BG-12.
In a separate note, Marko Kozul and Irene Lau, analysts for the Boston investment bank Leerink Swann, wrote, “We believe [Wall Street] expectations were low for the trial with little premium in Biogen Idec shares.”
Tackling the ALS challenge was thought to be a bold move for Scangos, who spun off Biogen Idec’s cancer research programs shortly after taking over as chief executive in 2010 to concentrate on areas such as neurology and hematology.
That summer, Biogen Idec entered into a deal with Knopp Biosciences under which the Weston company agreed to license dexpramipexole. As part of the agreement, Biogen Idec purchased $60 million of Knopp stock and made an upfront payment of $20 million to take the drug forward in clinical trials.
But as evidenced by Thursday’s setback, ALS has proved a particularly difficult condition for medical researchers to figure out.
“This is a complex disease,” said Steven Perrin, chief executive for the ALS Therapy Institute, a Cambridge group dedicated to finding treatments for Lou Gehrig’s disease. “It’s not an easy puzzle to solve. There’s lots of different things going wrong, and there’s a lot of variability in patients’ progression, which makes clinical studies more difficult.”
Regardless, Perrin said, ALS patients and neurological researchers remain upbeat about at least two other therapies still undergoing early-stage clinical studies.
“I’m sure our hopes will be dashed for a few days, but then we’ll rebound and start following another new drug in the pipeline,” said Sanford, the ALS patient from Tewksbury. “ After all, what other alternative exists for us?”
Robert Weisman can be reached at weisman@