The first Humira biosim is doing Amgen more harm than good—for now

The U.S. launch of a biosimilar to AbbVie’s Humira appears to be hurting the copycat’s developer itself.

After AbbVie reported a Humira U.S. sales decline of 26% in the first quarter, Amgen said its rival TNF blocker Enbrel suffered an even bigger loss.

Enbrel’s U.S. sales slid 33% in the first quarter compared with the same period last year, falling to $564 million. The drug’s sales haul was 29% smaller than Wall Street had expected.

Enbrel’s sales plummeted despite the drug having gained marginal volumes in the U.S., Amgen’s commercial chief, Murdo Gordon, told investors on a call Thursday. That means price declines played the key role in the sales slide.

Those price declines are thanks to the rollout of Amjevita, Amgen’s biosimilar to Humira. Given that Enbrel and Humira are direct competitors, increased competition and lower prices for one drug can affect the other.

Still, pricing pressures are only one element that dragged Enbrel down this quarter. Wholesalers and specialty pharmacies maintained lower inventory levels, possibly in expectation of buying more Humira biosimilars.

In addition, Amgen adjusted Enbrel’s number down by 9% to reflect changes to lower estimated sales in prior quarters, Gordon said.

For the rest of 2023, Amgen still expects Enbrel to gain volumes in the low-single-digit range thanks to a formulary win in January. Amgen also expects price declines to come at a milder pace, and it believes drug purchases will refill their inventories, Gordon said.

Despite the initial harm to Amgen’s key brand, that pain was likely going to come anyway. Numerous biosimilar developers plan to launch Humira copycats in 2023, so it likely made sense for Amgen to participate with its own version.

Meanwhile, Amjevita itself is having a slow start. In fact, Amgen expects the Humira biosimilar will see a sequential sales decline in the second quarter.

After the official U.S. rollout at the end of January, Amjevita collected $51 million in first-quarter sales. But that’s not to say doctors actually prescribed the biosimilar that much. The drug’s first-quarter haul mainly stemmed from purchases from healthcare facility groups called integrated delivery networks (IDNs), and it’s unclear how many doses were actually prescribed, Gordon said.

As the initial inventory rush subsides, Amgen thinks Amjevita’s second-quarter sales will decline from the first quarter.

The slow uptake prompted Wells Fargo analyst Mohit Bansal to question on Thursday’s call whether Amgen has squandered its first-mover advantage over the many Humira copycats that are scheduled to arrive later.

IDNs are where a lot of the initial uptake of biosimilars will be, Gordon said. Besides, Amjevita has access that’s on parity with the original Humira across the three large pharmacy benefit managers, he said.

Amgen is also differentiated from other Humira biosimilar developers, Gordon said, in that it covers “the customer base here quite effectively both in rheumatology and gastroenterology, having developed medical and sales teams that are out there right now building awareness and demand for Amjevita.”

The commercial exec reminded investors that Amjevita should experience a “gradual uptake,” saying that Amgen is using the head start to build demand.

Outside of the TNF business, Amgen’s oral psoriasis med Otezla, CGRP migraine med Aimovig and KRAS inhibitor Lumakras, each facing their own competitors, all delivered sales below analyst expectations.

After Mirati Therapeutics’ Krazati was approved in late 2022, Lumakras’ first-quarter sales in the U.S. declined 23% over the prior quarter. 

All told, Amgen’s total revenues in the first quarter decreased by 2% to $6.1 billion compared with the same period in 2022. Excluding revenues from a COVID antibody manufacturing collaboration, product sales actually increased by 2%, with growth coming from PCSK9 cholesterol drug Repatha, AstraZeneca-partnered asthma drug Tezspire and other meds.

Companywide, pricing pressure remains a problem for Amgen as the drugmaker touted a much larger 14% volume growth for its offerings. The California biotech in March cut 450 jobs, chalking up the layoffs to pricing pressure.

Meanwhile, Amgen also expects to close its $28 billion acquisition of Horizon Therapeutics in the first half of the year.