A new class of pain drugs that might offer an alternative to addictive opioids—if they’re safe enough to use chronically—is inching closer to an FDA review.
Regeneron Pharmaceuticals (NASDAQ: REGN) and partner Teva Pharmaceutical (NYSE: TEVA) said this morning that their experimental drug, fasinumab, hits its early goals in a Phase 3 trial in patients who have chronic pain from osteoarthritis of the knee or hip. Importantly, patients on fasinumab so far have not suffered joint damage, a side effect that caused the FDA to temporarily halt an earlier study testing the drug.
To be clear, however, the promising early results will have to hold up over time. Regeneron’s double-blind, placebo-controlled clinical trial will study patients for 52 weeks. On Thursday, The Tarrytown, NY-based drug maker released results after 16 weeks, which the companies described as a “sub-study.” Those preliminary results show the drug reduced pain and improved patients’ physical function, compared to a placebo—the two main goals of the 16-week analysis. The third main goal of the study will be assessed at 72 weeks—20 weeks after the 52-week study. At that point, researchers will be looking out for signs of joint damage.
Fasinumab is an antibody drug that blocks nerve growth factor (NGF), a protein that plays a role in pain signaling. Regeneron is one of several companies developing NGF-targeting drugs. Last month, Pfizer (NYSE: PFE) and Eli Lilly (NYSE: LLY) reported positive preliminary results for their NGF inhibitor, tanezumab. Johnson & Johnson (NYSE: JNJ) took its NGF inhibitor fulranumab into Phase 3 testing in osteoarthritis pain but stopped the program in 2016 after reassessing its drug portfolio. Regeneron is testing fasinumab in partnership with Teva, which paid the U.S. company $250 million in 2016 for partial rights to the drug.
NGF blockers have a checkered past. The hope is they can offer a treatment for chronic pain that gives patients an alternative to non-steroidal anti-inflammatory drugs, which can be harsh on the stomach, or the addictive opioids that are part of an ongoing nationwide epidemic. But NGF inhibitors have risks of their own. The FDA halted several studies of these drugs, among them, fasinumab, between 2010 and 2012 because of reports of joint damage. And just weeks after Regeneron and Teva struck up their partnership in 2016, safety concerns led the FDA to suspend a mid-stage study. One patient given the high dose of the drug developed arthropathy, a disease of the joints that can cause inflammation, a reduced range of motion, and stiffness. The regulator asked the company to adjust the design of the clinical trial.
More concerns with fasinumab emerged earlier this year. In May, an independent committee monitoring the Phase 3 study recommended stopping tests of the highest doses of the drug—3 mg every four weeks and 6 mg every eight weeks. Regeneron is currently only evaluating a lower (1 mg) dose of fasinumab either once every four or eight weeks.
Some patients have experienced joint pain, tingling sensations, a reduced sense of touch, and swelling in the limbs. But Regeneron and Teva said that those side effects were also seen in earlier tests and should be expected for an NGF-targeting drug.
Still, while the drug’s effectiveness so far is encouraging, it has to show it is safe for long-term use, wrote Evercore ISI analyst Umer Raffat. Raffat noted that Regeneron and Teva did not clearly state whether they’ve seen any rapidly progressing osteoarthritis type 2, a worsening of the condition that leads to rapid bone loss or permanent damage. “The results today are still quite preliminary and we need much more follow up and longer-term data to really understand if this drug could be real,” he wrote.
Regeneron and Teva said they plan to present more detailed results at an upcoming medical meeting.