FDA advisory panel backs Amgen's proposed biosimilar of AbbVie's Humira

An FDA advisory panel on Tuesday voted 26-0 in favour of recommending approval for ABP 501, Amgen's proposed biosimilar of AbbVie's Humira (adalimumab), to treat seven chronic inflammatory diseases for which the latter drug is cleared, including rheumatoid arthritis, psoriatic arthritis, Crohn's disease, ulcerative colitis and plaque psoriasis. The panel's backing follows an FDA staff report released earlier this month that concluded ABP 501 was "highly similar" to Humira. 

Amgen supported its application with Phase III results demonstrating clinical equivalence of ABP 501 to Humira in patients with moderate-to-severe rheumatoid arthritis. The drugmaker also included late-stage data showing its therapy was bioequivalent to Humira in patients with moderate-to-severe plaque psoriasis.

While the advisory committee's conclusions largely echoed those reached by FDA staff reviewers, some panellists had misgivings about approving ABP 501 for diseases for which it had not been clinically tested and urged the FDA to require companies to conduct post-market surveillance studies to ensure the biosimilars work as expected in those indications. "I voted yes despite reservations about extrapolating from the data we have, which was good, to the data we don't have and will never have," commented panel member Nancy Geller.

Meanwhile, patient advocate groups who spoke at the panel meeting raised concerns about the potential risk for allergic reactions or drug immunity once biosimilars become more available on the market. Specifically, they said these issues could arise when patients are switched by their pharmacy or drug benefit manager to another company's biosimilar. While the advisory committee was not asked to consider the switching issue, panellist Steven Solga remarked "these are important issues." The FDA has not yet decided whether biosimilars can be switched automatically by a pharmacist without a doctor's consultation, as is currently permitted with many generic drugs.

The agency is expected to render a final decision on ABP 501 by September 25. However, according to Evercore ISI analyst Mark Schoenebaum, the earliest Amgen could launch its biosimilar would be March 2017, potentially infringing Humira patents that AbbVie claims cover the drug in the US until 2022, although a key patent expires later this year. Wall Street analysts anticipate the patent disputes will be resolved in court, resulting in a potential ABP 501 launch sometime between 2018 and 2022. Some industry observers expect sales of Humira, which generated US sales of more than $8 billion last year, to fall as much as 18 percent in 2019.

Amgen requested FDA approval of ABP 501 last November, with a European submission filed the following month. 

Meanwhile, the same advisory panel is scheduled on July 13 to review Novartis' application for GP2015, its proposed biosimilar of Amgen's Enbrel (etanercept). An FDA staff report recently determined that GP2015 is "highly similar" to the reference product as a potential treatment for Enbrel's US-approved indications, including rheumatoid arthritis, psoriatic arthritis, plaque psoriasis, ankylosing spondylitis and polyarticular juvenile idiopathic arthritis.

For related analysis, see ViewPoints: How the FDA learned to stop worrying and love biosimilars and KOL Views: Is it a question of 'when' rather than 'if' there is a biosimilars explosion in the US market?  To learn more about the biosimilar market, read Biosimilar Index: Tracking the Biosimilar Development Landscape.

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