Credit: NPG

A panel of independent advisors to the FDA voted 21–3 in favour of approving Celltrion and Pfizer's biosimilar version of Johnson & Johnson's tumour necrosis factor (TNF)-specific antibody infliximab. The FDA is expected to make a regulatory decision on the biosimilar therapy in April, when Celltrion and Pfizer's product could become the first biosimilar antibody to be approved in the United States. Although the agency doesn't have to follow the recommendations of its advisors, it usually does.

The FDA gave its first green light to a biosimilar in 2015, when it approved Sandoz's biosimilar of Amgen's filgrastim, a granulocyte colony-stimulating factor (G-CSF), for the treatment of neutropenia. But because antibodies are more complex than proteins like G-CSF, industry is watching the infliximab biosimilar closely for clues about the biosimilar approval pathway.

A key point of discussion at the advisory panel meeting was whether to allow the extrapolation of clinical data in one indication to support approval in another indication. Johnson & Johnson's infliximab is approved for six indications, including rheumatoid arthritis, ankylosing spondylitis, Crohn disease and ulcerative colitis. Celltrion and Pfizer demonstrated clinical biosimilarity for their product only in patients with rheumatoid arthritis and ankylosing spondylitis. The advisory panel voted in favour of allowing extrapolation of this data, backed by analytical data on the biophysical characteristics of the biosimilar, to support approval across all indications.

The European Medicines Agency approved the biosimilar in the European Union in 2013. An approval in the United States would be a further blow for Johnson & Johnson, which sells around US$6.8 billion worth of infliximab each year. Johnson & Johnson is suing Celltrion, however, alleging that the biosimilar will infringe several US patents. This lawsuit could keep the biosimilar off the US market even in the case of an approval.

Many other lucrative biologics will come off patent in the next few years, prompting Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, to warn last month that the number of biosimilar applications is set to “explode”. Other blockbuster antibodies that could see biosimilar competitors in the United States within the next 4 years include AbbVie's TNF-specific adalimumab, Roche's vascular endothelial growth factor (VEGF)-specific bevacizumab and Roche's CD20-specific rituximab (Nat. Rev. Drug Discov. 15, 13–14; 2016).