Event – Humira biosimilar faces its clinical hurdle

Analysis

While the crown of Abbvie’s Humira as the biggest-selling drug of all time remains in place, it might still come as a surprise just how bright a future the sellside is forecasting for Amgen’s ABP 501, likely Humira’s first biosimilar version.

With a staggering NPV of $6.2bn, based on EvaluatePharma sellside consensus, ABP 501 is one of pharma’s most valuable assets awaiting approval. And while it is still unclear when it might enter the US market – this will largely be determined by the courts – next month it could get its biggest endorsement to date when a US FDA adcom is convened to consider regulatory approval.

Company Amgen
Project ABP 501
Market cap $110bn
Project NPV $6.2bn
% of market cap 6%
Event type US adcom
Date July 12, 2016

The US approval process for biosimilars is new relative to that in regions like the EU, and the relevant pathway, 351(k), has only been in place for six years. But at least by now there is precedent to go on: two biosimilars, Zarxio and Inflectra, have already successfully negotiated this route to secure the FDA’s blessing.

The advent of Humira biosimilars has been seen as a far more significant test of the system, largely on account of the market size. As such the issue of interchangeability will remain key; the Inflectra precedent is that a biosimilar cannot be substituted for the brand product at a pharmacy, and thus marketing and pricing become more important.

The fundamental basis of the US advisory panel, the arthritis advisory committee, will be a review of the available data Amgen has generated. The key clinical studies are in moderate to severe plaque psoriasis and rheumatoid arthritis, and both demonstrated ABP 501’s clinical equivalence to Humira.

However, Amgen will be looking not just to show ABP 501’s potential in these uses but also in most of Humira’s other approved indications, including Crohn’s disease, ulcerative colitis and ankylosing spondylitis.

As long as there is sufficient justification to extrapolate the bioequivalence – based, for instance, on mechanistic attributes – these other indications should also make it onto ABP 501’s label. The FDA has set a biosimilar user fee act – BSUFA, as opposed to the more common PDUFA, which applies to standard product filings – date of September 25.

When?

Of course, the more important issue is when a Humira biosimilar might be launched commercially if it gets the US regulatory nod. US patents on the MAb start to expire this year, but Abbvie has vowed to keep biosimilars off the market until 2022 (Can Humira still dominate in 2022?, April 21, 2016).

One legal dispute has already played out, and it went in Abbvie’s favour, with an Amgen inter partes review challenge to two recently granted Humira formulation patents being rejected. Still, the battle is nowhere near over.

As is to be expected, Amgen’s plans remain secret. “It remains unclear to us whether Amgen expects to be launching in 2017, or wants to be in a position to launch, if the patent defences by Abbvie are unsuccessful,” wrote Leerink analysts recently.

It is not even clear whether Amgen and Abbvie have engaged in the so-called patent dance – a procedure whereby the biosimilar and reference product manufacturers exchange information on production processes to determine if they violate any unexpired patents.

This was thought to have been a requirement under biosimilars legislation, but a year ago the Federal Appeals Court ruled that it was merely optional. The case that decided this was between Sandoz and Amgen, and since Amgen lost it can rely on first-hand knowledge.

This is another precedent that, if played out in the Humira biosimilar battle, Abbvie will surely pursue far more avidly than did Sandoz. Still, a biosimilar version of Humira is not a question of if but of when, and next month’s panel should clarify at least some of the uncertainty.

To contact the writer of this story email Jacob Plieth in London at jacobp@epvantage.com or follow @JacobPlieth on Twitter

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