There was more bad news on Dec. 27 for companies developing anti-nerve growth factor (NGF) drugs: U.S. regulators put Regeneron's candidate REGN475, in development with Sanofi-Aventis, on hold late last week, Regeneron said in a regulatory filing Monday.

That news was followed by word Dec. 28 that Johnson & Johnson's NGF inhibitor fulranumab also was placed on clinical hold. In addition, AstraZeneca announced it has voluntarily ceased its work on MEDI578, a nerve inhibitor in early-stage development at its subsidiary, MedImmune. (Editor's note: This story has been corrected to note that J&J has not ended development of fulranumab, as our initial story stated. J&J said it is working with FDA to resolve the issues related to the trial's clinical hold.)

The latest setbacks for NGF inhibitors were triggered by a patient in another company's trial developing a serious bone disorder, known as avascular necrosis. It's caused when a lack of blood supply causes bone tissue to die.

Following similar concerns around other NGF-targeting drugs in 2010, it's no surprise that by now FDA believes the whole class of drugs could be unsafe. Regeneron says as much in its filing: "The FDA believes this additional case provides evidence to suggest a class-effect." No word yet if or when REGN475, also known as SAR164877, will get a green light, but Regeneron noted that there are no current trials of the drug either enrolling or recruiting patients.

Trials in osteoarthritis pain of Pfizer's anti-NGF candidate tanezumab, believed to have been the most advanced in development, were put on hold in June 2010 following FDA concerns that a number of patients' osteoarthritis symptoms were worsening, rather than improving (Also see "No Relief For Pfizer As It Shuts Down Additional Tanezumab Trials" - Pink Sheet, 20 July, 2010.). In some cases this led to joint replacements.

Because of the hold, Pfizer terminated most of its tanezumab trials earlier this year, but it is pressing on with two trials to study the drug, one in combination with opioid medication, the other as a standalone treatment in patients with chronic pancreatitis, according to clinicaltrials.gov.

None of this will provide much Yuletide cheer to the likes of Abbott, which paid a whopping $170 million up-front for PanGenetics' Phase I anti-NGF antibody last year.

Also in the pain domain but more positive was the news that King Pharmaceuticals and Pain Therapeutics' re-submission of abuse-resistant oxycodone (Remoxy) was accepted by FDA. This time, Pfizer will be pleased: it has agreed to buy King for a cool $3.6 billion (Also see "Pfizer To Buy King Pharma For $3.6 billion In Order to Strengthen Pain Franchise" - Pink Sheet, 12 October, 2010.).

-Melanie Senior (m.senior@elsevier.com)

Regeneron, J&J, AstraZeneca Pull Plug On NGF Inhibitors In Development For Pain Indications

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