Bad Knees? Burlington biotech investigates new treatment for osteoarthritis | Crain's Boston

Bad Knees? Burlington biotech investigates new treatment for osteoarthritis

Knee x-ray. Photo by Nevit Dilmen via Wikipedia

A local biotech company on Thursday began its latest round of clinical trials for a drug treating osteoarthritis, the degenerative joint disease behind tens of millions of painfully creaky knees in the United States.
Earlier this month the Food and Drug Administration accepted a New Drug Application from Burlington, Mass.-based Flexion Therapeutics, Inc., and will consider their arthritis treatment Zilretta for approval by the end of this year.
At the same time Flexion will be doing additional testing on Zilretta in approximately 200 patients with osteoarthritis of the knee at up to 20 clinical sites across the country. The trials will evaluate the safety of repeat administration of Zilretta.
Osteoarthritis is a common and painful condition in older people, who suffer when wear-and-tear grinds down the cartilage in a joint, causing pain, swelling and stiffness. It is the most common form of arthritis in the knee, currently afflicting more than 30 million people in the U.S.—mostly people over 50 years old, according to the Centers for Disease Control and Prevention.
Millions of those patients already get steroid injections to treat osteoarthritis of the knee every year. Steroids like hydrocortisone relieve the painful inflammation associated with the disease, but typically only last for a few weeks.
Steroid shot therapy is still a short-term treatment for a chronic problem, but Flexion founders Dr. Mike Clayman and Dr. Neil Bodick say their drug is designed to be the first extended-release treatment. Zilretta could last up to three months, erasing the painful lapses in treatment. The key, says Flexion founder Dr. Clayman, is a molecule called polylactic-co-glycolic acid (PLGA) that keeps the steroids from rushing out of the knee.
Their new drug Zilretta, consists of a ball of PLGA about the size of a dust speck and peppered with crystals of the steroid triamcinolone. Viewed through a microscope and colorized red and green, it resembles a misshapen Christmas ornament. That proprietary compound, which Flexion has dubbed a “microsphere," acts as a biological “depot” for steroids in the joint, explains Clayman, allowing them to seep slowly into the knee over time instead of all at once.
“It occurred to us that if you could formulate the steroid with a polymer, you could make it last as long as three months,” says Clayman. “Think of it as a reservoir of drugs that continues to slowly provide the drug you want, when you want to provide it.”
Dr. Shane Shapiro, a physician at the Mayo Clinic in Jacksonville, Fla. who is not associated with Flexion, says if Zilretta delivers on its promise to prolong the beneficial effects of corticosteroid injections, it could help patients for whom the steroids dissipate more quickly. 
"It's always nice to have options," says Dr. Shapiro. "[Zilretta] has the potential to improve treatment for some patients."
Dr. Shapiro, who says such injections occur multiple times every day at the Mayo Clinic, says anecdotally that may be a small percentage of patients, but he adds data suggests the steroid injections wear off after about six weeks.
Clayman says a more effective treatment could also broaden the options of osteoarthritis patients, who typically have to choose between chronic pain and invasive surgery.
Knee replacement is one of the most common surgeries in the country, and its popularity is growing. According to research from the University of Washington, however, it fails to relieve pain in about half of patients.
Flexion (pronounced FLECK-shun) started in 2007 when Dr. Clayman and Dr. Bodick left Eli Lilly & Company to pursue what eventually became Zilretta, which was recently patented through 2031.
Clincial trials of the drug will take one year, as patients undergo regular physical examinations, knee assessments and X-rays to determine Zilretta’s effectiveness. 
In the meantime the company is expanding its sales force, expecting to more than double in size from 100 employees to 250 by end of the year.
Editor's note: This story has been updated to make it clear that Flexion began a new clinical trial of its own on Thursday, and that earlier this month the FDA accepted Flexion'a "New Drug Application" for Zilretta.
February 23, 2017 - 3:52pm