Baxter International Inc.’s Gammagard, used to treat immune system disorders, halted the progression of Alzheimer’s disease for as long as three years in a trial of 16 patients, researchers said.
In the study, four patients given the ideal dose at the start of the trial experienced lasting improvement. Five patients initially given a placebo and seven others on varying amounts of Gammagard, experienced no benefit until they were switched to the right dose, according to the research presented at the Alzheimer’s Association’s annual meeting in Vancouver.
The result offers a “tantalizing” glimpse of the drug’s potential, said William Thies, chief medical and scientific officer at the Alzheimer’s Association. A definitive study of 390 patients will be completed this year and released in early 2013, said Norman Relkin, the lead researcher, and the director of the Memory Disorders Program and a neurologist at New York Presbyterian/Weill Cornell Medical Center.
“It’s extraordinarily unusual,” to have such a striking effect in all the treated patients, Relkin said in an interview. “In my practice, which I think is reflective of most Alzheimer’s specialists in the world, if we see a patient go more than 18 months without changing their scores, we question whether they actually have Alzheimer’s disease.”
Baxter, based in Deerfield, Illinois, funded the study, though it doesn’t hold a patent on the drug also known as intravenous immunoglobulin, or IVIG. The treatment has been used for three decades to replace antibodies in patients who don’t make enough to prevent infections. Similar products are also sold by Grifols SA, based in Barcelona, Spain, Melbourne-based CSL Ltd. and closely held Octapharma AG based in Lachen, Switzerland.
Baxter rose 1.7 percent to $55.68 at the close in New York. The shares have fallen 8.4 percent in the past 12 months.
More than 5 million Americans now suffer from the disease, and the number is expected to increase to 16 million by 2050, according to the National Institutes of Health. Existing drugs temporarily ease symptoms of the condition, while patients continue the inexorable slide into dementia.
An unequivocally positive result in the next Gammagard study may create a potential market worth $7.2 billion in the U.S. alone by 2017, said Glenn Novarro, an analyst for RBC Capital Markets in New York. The opportunity is creating tension for companies that sell IVIG, which is culled from thousands of blood plasma donations and costs in excess of $50,000 a year.
Manufacturers already sell all the IVIG they produce, Novarro said in a telephone interview. They must decide now whether to start expanding their production abilities, which will take time, or wait until the study results are announced and miss the initial surge in demand, he said.
Researchers tracked 16 patients in the study, including 11 treated with Gammagard and 5 given a placebo. The four given an intermediate dose of the drug that performed best in earlier research had the most benefit, with no signs of worsening on tests of thinking, memory, daily function and mood over three years.
Three of the four patients continue to take Gammagard, more than six years after they began treatment, Relkin said. The fourth was in his 90s when he developed an unrelated medical condition and stopped treatment.
“One of the goals of treatment is to keep people in the high-functioning, mild stage of the disease for as long as possible,” he said. “These patients have spent an unprecedented portion of time in the more mild stage and enjoyed a good quality of life.”
The results weren’t uniformly positive. Patients who were switched to a variety of doses of the medication after initially getting a placebo continued to decline, an unexpected finding, Relkin said. After a year of therapy, all were switched to the intermediate dose and stabilized, showing the dose of the medication is critical, he said.
Baxter announced in April it is building a manufacturing facility in Covington, Georgia, at a cost of more than $1 billion over the next five years. The plant will make the company’s plasma-based treatments, with commercial production slated to begin in 2018. It also started a second pivotal study of Gammagard in Alzheimer’s disease, a confirmatory trial typically needed for U.S. regulatory approval.
Brian Kyhos, a Baxter spokesman, declined to discuss the company’s planning in advance of next year’s study results.
The report precedes studies expected to be released soon on two rival medicines that use a targeted approach to stop the disease that starts with mild forgetfulness and eventually robs patients of memories and independence. Bapineuzumab, from Johnson & Johnson, Pfizer Inc. and Elan Corp., is vying with Gammagard and Eli Lilly & Co.’s solanezumab to be the first broadly available drug designed to target a cause of Alzheimer’s.
RBC’s Novarro predicts Gammagard will be successful in the larger study, based on his conversations with other doctors who have had patients on the medication for years. Still, the small number of patients in the current study makes him wary of the outcome.
“It’s hard to get too excited yet,” he said. “We’ve all seen too often 15 patients with good data, and when the big trial comes out you don’t see the same result.”
IVIG was conceived to get antibodies to fight amyloid plaque that builds up in the brains of Alzheimer’s patients. The findings suggest it may play a more complex role, with its ability to control inflammation being just one critical component of the medication, Relkin said. Ultimately, it’s more likely to mitigate the toxicity of the amyloid plaque that’s a hallmark of the disease, rather than squelch it, Relkin said.
If the larger study is successful, the field will turn toward figuring out which components of IVIG were responsible, said Thies of the Chicago-based Alzheimer’s Association. The current therapy is a shotgun approach, using all the antibodies that a normal, healthy young adult produces, Relkin said.
“If, when the smoke clears, it’s successful, we’re going to have to go through the billions of antibodies to see which one was the silver bullet,” he said. “We are actively working on the question of what might be the active ingredient.”