Pfizer Inc. / Rinat Neuroscience Corporation

Chronic Pain (Osteoarthritis and Low Back Pain)

Disease Overview

Chronic pain from osteoarthritis and low back pain affects tens of millions of US adults and is conventionally treated with NSAIDs, acetaminophen, and opioids. Each class carries cardiovascular, GI, hepatic, or addiction risks, creating durable demand for non-opioid analgesics with novel mechanisms.

Competitive Landscape

In 2006, the chronic pain market was dominated by COX-2 inhibitors (Pfizer's own Celebrex), generic NSAIDs, and opioids (OxyContin, Vicodin, Lyrica/pregabalin). Vioxx had been withdrawn in 2004, and the FDA was tightening cardiovascular labeling on the COX-2 class, opening a window for non-opioid, non-NSAID mechanisms. Rinat's RN624/tanezumab was the most clinically advanced anti-NGF (nerve growth factor) monoclonal antibody, a wholly new pain mechanism. The deal also brought Rinat's anti-amyloid-beta program (later RN1219) into Pfizer's Alzheimer's pipeline at a time when Eli Lilly's solanezumab and Elan/Wyeth's bapineuzumab were the only anti-Abeta antibodies in late development. Tanezumab eventually showed Phase 3 efficacy in osteoarthritis and low back pain, but rapidly progressive osteoarthritis (RPOA) safety signals led an FDA advisory committee to vote 19-1 against approval in March 2021, and EMA refused authorization in September 2021. The acquisition was strategically prescient on mechanism but commercially failed on safety.