Thumbs-down from FDA experts for Pfizer/Lilly's painkiller tanezumab

After more than a decade of fraught clinical development it looks like the end of the line for Pfizer/Lilly painkiller tanezumab, which promised to be an alternative to addictive opioid painkillers.

Pfizer has asked the FDA for a licence for tanezumab in moderate to severe osteoarthritis pain, where other painkillers aren’t working or are inappropriate.

This week FDA appointed experts on safety and pain met at a joint meeting to discuss the company’s dossier – and the feedback was not good.

After a withering review from the FDA’s own staffers in a briefing document posted ahead of the meeting, the experts overwhelmingly said they were unconvinced about Pfizer’s plan to mitigate a safety issue that has dogged the drug throughout trials.

The drug does have a painkilling benefit but a small number of patients go on to develop a nasty condition called Rapidly Progressive Osteoarthritis Rheumatology (RPOA), where joints deteriorate.

In one large study mentioned in the document of tanezumab 11 patients out of 998 on the highest dose developed RPOA (1.1%) while at the lower dose that the companies are aiming to market, three out of 1,002 patients developed the condition.

Experts were asked one question about whether Pfizer’s proposed risk evaluation and mitigation strategy (REMS) was enough to ensure tanezumab’s benefits outweigh its risks.

Just one expert voted in favour of the REMS plan, with the remaining 19 voting against.

The FDA doesn’t have to follow the advice of its experts and after such a resounding no-confidence vote it looks unlikely that the regulator will approve.

Ken Verburg, tanezumab development team leader at Pfizer, said the company is “disappointed” by the outcome but remains confidence that the drug’s benefits outweigh its risks.

He added: “Many of these patients have exhausted available therapies, have not had a new class of medications available to them in more than a decade and are eager for new, non-opioid options.”

Tanezumab is from a class of drugs known as nerve growth factor (NGF) inhibitors, which has been dogged by safety issues after more than a decade of clinical development.

Regeneron and Teva’s fasinumab is the only other serious contender from the class, which is in late stage clinical development.

Johnson & Johnson axed development of its rival fulranumab five years ago and returned rights to Amgen, although at the time the company said the decision was not based on any emerging safety concerns.

Amgen doesn’t seem to have done anything with fulranumab since – it is not mentioned the company’s pipeline round-up – meaning the search for a new class of non-addictive painkillers may continue for some time.

Another potential painkilling option is offered by Flexion and its Zilretta (triamcinolone acteonide) an extended release injectable suspension that has been on the US market for osteoarthritis knee pain for more than three years.