Pfizer/Eli Lilly's Tanezumab Safety Profile Fails To Impress FDA Even After 15 Years Of Development Across 41 Trials

Ahead of an advisory committee meeting scheduled for later this week, the FDA released its in-depth review of Pfizer Inc PFE and Eli Lilly And Co’s LLY tanezumab, an anti-NGF osteoarthritis drug.

What Happened: Potential FDA approval for tanezumab still looked rocky as the regulator casts doubt over its safety.

The primary safety worry is rapidly progressing osteoarthritis, dubbed as RPOA, which the companies are aware of, reports FDA in a regulatory document.

FDA explained, noting, “The review team has concerns that the Applicant’s proposed risk evaluation and mitigation strategy (REMS) is not sufficient to mitigate the risk of RPOA and would not ensure that the benefits of tanezumab outweigh the risks of RPOA.”

In spite of the risk mitigation strategies in clinical studies, the risk of developing RPOA remained concerning, as a large number of patients with RPOA required total joint replacements (TJR) - 15% of patients progressed to TJR following RPOA1, and 60% of patients with RPOA2 progressed to TJR.

The FDA said that though tanezumab proved to be effective, its effect size “is modest, and there is no convincing evidence of a superior efficacy of tanezumab over NSAIDs.”

Why It Matters: Tanezumab has been in development for more than 15 years, across 41 clinical studies and at least 43 formal meetings with the FDA.

Another concern was that the drug could cause abnormal peripheral sensation characterized as (mostly) mild, self-limited mononeuropathy (singular nerve damage), with the most common coming out as carpal tunnel syndrome.

Price Action: PFE shares are trading 1.2% higher $35.96, and LLY is up 0.52% at $185.25 in market trading hours on the last check Monday.