(Bloomberg) -- European regulators suspended the approval of Pfizer Inc.’s sickle cell anemia drug, Oxbryta, citing a higher rate of disease complications in patients who started taking it.
The move comes less than a day after Pfizer abruptly announced a worldwide withdrawal of the drug, citing an “imbalance” in deaths and sickle-cell complications in patients. The European Medicines Agency had scheduled a special meeting on the drug’s safety early Thursday.
Later in the day, the EMA cited data showing that those taking the drug had a higher rate of pain crises after starting treatment. This raised “serious concerns about the safety of Oxbryta,” the EMA said in a statement. The agency also announced in July it was investigating 16 deaths, which still haven’t been officially attributed as being caused by Oxbryta.
The US Food and Drug Administration alerted doctors to stop prescribing the drug and advised patients to seek advice from health professionals about other treatment options. The agency said it has been monitoring Oxbryta’s safety since it went on the market and will communicate any additional findings, if necessary.
The withdrawal is “a real surprise” and could result in a write-off of nearly $5 billion for Pfizer, Mizuho analyst Jared Holz said in a note to clients on Thursday. It’s a black eye for the drugmaker, which spent $5.4 billion to acquire Oxbryta’s developer, Global Blood Therapeutics, just over two years ago.
Pfizer has had mixed results in developing new sources of revenue to replace declining sales of its Covid vaccine. It acquired a promising stable of cancer drugs in its $43 billion acquisition of Seagen Inc. last year. But its high-profile attempts to develop a pill to treat obesity have mostly fallen flat. And earlier this year, the gene therapy for Duchenne muscular dystrophy that the company was testing failed in a large trial.
‘Pretty Startled’
Sharl Azar, a hematologist at the Massachusetts General Hospital, said he was “pretty startled” by Pfizer’s decision to pull the drug. His team has been reaching out to patients this morning to “assuage their fears” and help them get off the drug. Importantly, he said, patients shouldn’t stop taking Oxbryta suddenly, and instead must taper off.
He noted another drug for sickle cell disease, Novartis AG’s Adakveo, was withdrawn from the European market last year after a clinical trial found no statistically significant difference between it and a placebo in reducing pain crises. Novartis said its drug is still approved in the US.
“It leaves a lot of questions in patients’ minds,” Azar said. “I’m sure it leaves them very panicked, and we want to reassure patients as much as possible.”
Oxbryta was once hailed as a first-in-class therapy that targeted the root cause of sickle cell disease. It was approved in 2019 by US regulators using a controversial expedited mechanism that allows drugs to get on the market based on preliminary data. Drugmakers then must conduct additional studies to prove the treatments work. Oxbryta later received approval in Europe.
When Pfizer acquired Global Blood Therapeutics in 2022, it said that Oxbryta and other sickle cell drugs under development could lead to more than $3 billion in annual sales.
But now, after considering its data, Pfizer concluded that the benefit of Oxbryta “no longer outweighs the risk.”
The company, which also is discontinuing clinical trials of Oxbryta, separately said the actions won’t have an immediate impact on other experimental drugs it is testing for sickle cell disease.
“This decision is specific to Oxbryta. We are continuing to advance our pipeline,” a Pfizer spokesperson said in response to Bloomberg News questions. The company will review all available data to determine next steps, if any, the spokesperson said.
In recent earnings calls, Pfizer had also talked up the potential of follow-on programs from the Global Blood Therapeutics acquisition. In particular, Chief Executive Officer Albert Bourla has said an experimental sickle cell treatment, known as GBT-601, showed promise in a mid-stage study late last year, and could represent a “potential step-wise evolution over Oxbryta.”
Pfizer shares were little changed in New York.
--With assistance from Fiona Rutherford and Amber Tong.
(Adds FDA statement in first section.)
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