Regeneron, Teva’s pain drug clears phase 3 efficacy bar

A phase 3 osteoarthritis trial of Teva and Regeneron’s fasinumab has met its co-primary endpoints. The anti-NGF antibody cleared the efficacy bar but triggered the expected safety alarms, keeping it on the tail of Pfizer and Eli Lilly’s rival asset without dispelling doubts about its prospects.

Anti-NGF antibodies looked set to be the next big thing around the start of the decade, but reports of joint replacements in patients taking the drugs led the FDA to issue clinical holds. The safety scare thinned out the field, but Regeneron and Pfizer kept going, leading to partnerships with Teva and Lilly, respectively. Regeneron had a wobble in 2016 when the FDA hit it with a clinical hold, and again in May when the data monitoring committee advised it to halt the high-dose arms of its phase 3 trials.

Now, Regeneron is a step closer to finding out whether its persistence will pay off. Administering fasinumab to patients with chronic pain from osteoarthritis of the knee or hip every four or eight weeks caused significant improvements in pain and physical function after 16 weeks.

The trial hit all of its key secondary endpoints, too, but the positive efficacy readout could have been rendered moot by a poor safety profile. Regeneron saw some of the joint issues that have blighted the NGF class. The placebo-adjusted rate of arthropathies was 2%. Many of the cases involved rapid progressive osteoarthritis, the adverse event that derailed the first wave of anti-NGF clinical trials.

Regeneron’s results show the risk remains but, given the need for nonopioid painkillers, it thinks the drug could have a future. Pfizer’s anti-NGF drug tanezumab looks to have a similar safety profile. In a phase 3 readout last month, Pfizer linked tanezumab to rapidly progressive osteoarthritis in less than 1.5% of participants. No subjects in the placebo cohort suffered from the condition.

Pfizer has yet to post a look at its efficacy data, but its brief statement suggests the two drugs may be comparable on that front, too. Both clinical trials achieved statistically significant improvements by administering two doses eight weeks apart. 

With both programs clearing the first phase 3 hurdle, attention now turns to upcoming readouts. The fasinumab trial is dosing patients for another 36 weeks, after which investigators will monitor their safety for a further 20 weeks. Regeneron and Teva are running other phase 3 trials of fasinumab, too. In parallel, Pfizer and Lilly are gathering the clinical efficacy and safety data to support a planned filing for FDA approval.

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