Regeneron Pharmaceuticals has seen its share of ups and downs over the years developing a drug for chronic pain that could represent an alternative to addictive opioids. And another roadblock just emerged this morning.
Regeneron (NASDAQ: REGN) and partner Teva Pharmaceutical Industries (NYSE: TEVA) said this morning that safety issues have prompted the FDA to suspend an ongoing mid-stage study of pain drug fasinumab in patients with chronic low back pain. A single patient in the study on a high dose of fasinumab experienced arthropathy—a term used to describe a disease of the joints. As a result, the FDA placed a clinical hold on the trial and requested an amendment to the study’s design. Teva paid Regeneron $250 million up front just last month for partial rights to fasinumab.
Regeneron reviewed the data from the mid-stage trial after the FDA hold. It said that while all doses of fasinumab appeared effective and safety issues were “generally consistent with what has been previously reported with this class [of drugs],” it has altered the design of an upcoming Phase 3 trial in low back pain patients (a different trial than the mid-stage study mentioned above, also being done in partnership with Teva). In a separate fasinumab study in osteoarthritis patients, Regeneron found that arthropathy was more common at higher fasinumab doses. As a result of these findings, Regeneron said the Phase 3 low back pain trial won’t include patients with advanced osteoarthritis. And the companies will only use lower doses of fasinumab in their ongoing osteoarthritis studies.
Regeneron and Teva will submit both plans to the FDA for review.
Safety problems have been a concern for fasinumab, and other drugs like it, for years. Fasinumab is an antibody that blocks the activity of a protein, called nerve growth factor, involved in pain signaling. NGF blockers were heralded as new potential blockbusters for drugmakers several years ago, but the FDA halted several ongoing studies between 2010 and 2012 due to reports that they were actually exacerbating joint damage. The holds were lifted last year, freeing development of the drugs, but expectations have since been dialed down as questions about their long-term safety remain.
Two NGF blockers are still advancing forward: fasinumab, and a rival drug from Pfizer and Eli Lilly called tazenumab. Pfizer and Lilly, which aim to win FDA approval of tazenumab in 2018, are ahead of Regeneron. But Regeneron got some help just last month, when Teva aligned with the company on fasinumab and, as a result, took on some of the remaining risk (the two are splitting the costs of development).