Startup seeks a better treatment for joint pain — using ingredient found in chili plants

Hiroko Masuike/The New York Times

Jeffrey B. Kindler, chairman and CEO of Pfizer at a press conference in New York in January 2009.

By Globe Staff 

When Jeffrey B. Kindler joined a startup company in 2013 that was developing treatments for chronic pain, he saw a huge potential market, given the legions of baby boomers struggling with arthritis in their joints.

One of them is his wife.


Sharon Sullivan, now 61, has suffered for years from osteoarthritis of the knee. She has tried treatments ranging from over-the-counter pain relievers to cortisone shots. None provided lasting relief, said Kindler, the former chief executive of Pfizer Inc.

But he’s optimistic that the Boston start-up company he runs, Centrexion Therapeutics Corp., is closing in on a more effective way to treat such debilitating pain. Centrexion announced Tuesday that it has raised another $67 million in venture capital to fund two late-stage clinical trials of an experimental medicine that uses a synthetic form of trans-capsaicin – the active ingredient in the chili plant — to provide long-lasting relief without steroids or opioids.

In early trials, the experimental medicine demonstrated that it rapidly reduced pain after being injected into a joint. The medicine binds to receptors at the end of nerve fibers to stop pain signals from being sent to the brain, providing six months of relief without any more side effects than a placebo. If those findings hold up in the late-stage trials scheduled to start early this year, Kindler said, patients eventually could get twice-a-year injections from their doctors to keep pain at bay.

“This could really be a game-changer in the way pain patients are treated for moderate to severe osteoarthritis,” he said. All told, Kindler’s company has raised $147 million in four rounds of fund-raising since it was founded four years ago.

Centrexion is hardly alone in the pursuit of better pain relief medicines. In October, the Food and Drug Administration approved Zilretta, an inflammation-suppressing non-opioid steroid, made by Burlington-based Flexion Therapeutics Inc. It, too, is injected but uses a novel delivery system: small particles called miscrospheres that gradually release the medicine in joints over an extended period. Flexion’s chief executive, Michael Clayman, said it has the potential be a blockbuster, meaning a treatment that generates more than $1 billion in annual sales.


Demographics account for much of the interest in pain relief. Nearly 67 million Americans are expected to suffer from arthritis by 2030, according to a decade-old article in the medical journal Arthritis & Rheumatology. Pain, said Kindler, is the leading source of disability claims. And, of course, it has contributed to the deadly opioid crisis — many patients who were prescribed painkillers like OxyContin and Percocet by their physicians became addicted, and later turned to heroin.

Knee osteoarthritis, in particular, has become twice as common since 1950, according to a recent study in the journal Proceedings of the National Academy of Sciences, and now affects about one in five American adults age 45 or older.

Although some medical specialists have attributed the increase in knee osteoarthritis to the fact that people are living older and obesity is more common, the study said that those factors alone don’t account for the surge. Among the other factors the authors recommended be studied are whether a decline in physical activity has led to thinner cartilage in joints and whether modern diets rich in refined carbohydrates have worsened chronic mild inflammation.

The most recent fund-raising round by Centrexion was led by New Enterprise Associates, a venture capital firm based in Menlo Park, Calif. Centrexion was founded in Baltimore in 2013 and moved to Boston in late 2016.

Jonathan Saltzman can be reached at