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Hello and happy Tuesday! Today, we’re unpacking a shocking move from Pfizer. 

The pharmaceutical giant last week announced it would voluntarily withdraw its sickle cell disease therapy, Oxbryta, from worldwide markets — to the surprise of doctors, patients and investors.

Here’s why the drug is important: Oxbryta is one of at least six treatments for the inherited blood disorder. The drug first won accelerated approval from the U.S. Food and Drug Administration in 2019, which requires further trials to confirm its benefits to patients. 

Oxbryta was one of the centerpieces of Pfizer’s $5.4 billion acquisition of Global Blood Therapeutics in 2022. 

Sickle cell disease causes red blood cells to become misshapen half-moons that get stuck inside blood vessels, which can restrict blood flow and cause what are known as pain crises. It impacts roughly 100,000 people in the U.S., many of whom are Black, according to data from the Centers for Disease Control and Prevention.

The company on Wednesday said the decision to withdraw Oxbryta was based on data showing a higher risk of deaths and complications in patients treated with the once-daily pill. In a release, Pfizer said the “totality of clinical data” on Oxbryta now indicates that its overall benefit “no longer outweighs the risk” in the patient population for which the drug is approved. 

As part of that move, Pfizer is also discontinuing all studies and access programs related to the treatment. 

The FDA on Saturday urged healthcare professionals to stop prescribing Oxbryta. The agency also said patients and caregivers should contact their healthcare professional about stopping the drug and starting another treatment option. 

European regulators on Thursday also said patients in trials had higher rates of pain crises after they started treatment with Oxbryta than they did before taking it. Those regulators recommended suspending the drug’s marketing authorization. 

That all may sound cut and dry. But Oxbryta’s withdrawal is raising concerns. 

Its sudden absence from the market leaves doctors, sickle cell disease patients and patient advocates scrambling for more information on the decision and guidance on what they should do next, STAT reported on Friday. And while taking Oxbryta could put patients at risk, it is not entirely clear what they may experience if they abruptly stop treatment with the drug. 

In a statement last week, the National Alliance of Sickle Cell Centers urged patients not to abruptly stop taking Oxbryta. The group, which supports health centers that administer treatments for the disorder, urged all patients currently taking Oxbryta to make an appointment with their doctor and develop a plan for gradually tapering off the medication.  

Oxbryta’s withdrawal will be a “significant blow” to patients with sickle cell disease “who have been historically underserved,” BMO Capital Markets analyst Evan Seigerman wrote in a research note last week. 

The FDA last year approved two gene therapies to treat sickle cell disease, a landmark decision that gave hope to patients who suffer from the debilitating disease. But health officials have so far struggled to find a way to provide equitable access to the costly treatments. 

Vertex Pharmaceuticals‘ gene therapy Casgevy costs $2.2 million per patient, and Bluebird Bio‘s treatment Lyfgenia lists for $3.1 million per patient. 

Other companies such as Agios Pharmaceuticals and Fulcrum Therapeutics are developing new experimental treatments for sickle disease. Notably, some Wall Street analysts said Pfizer’s withdrawal of Oxbryta could accelerate the timeline for clinical trials on those rival drugs. 

If Agios’ experimental drug, mitapivat, shows a benefit in reducing pain crises in clinical trials, “We anticipate this will enable an easier regulatory review, especially now considering the greater demands from patients who can no longer access Pfizer’s drug,” Piper Sandler analyst Christopher Raymond said in a research note last week. 

Meanwhile, the financial impact of the Oxbryta withdrawal is “somewhat modest for a company of Pfizer’s size,” Guggenheim analysts said in a note last week. 

They said Oxbryta sales have been relatively modest for the company, amounting to $328 million last year. But the analysts noted that Oxbryta sales were expected to increase to around $750 million by the end of the decade, citing FactSet consensus estimates. 

Pfizer’s decision will likely raise questions around the company’s ability to grow through the end of the decade when it faces several drug patent expirations and “other challenges to their current growth drivers,” according to Guggenheim. The analysts also said the Oxbryta withdrawal raises questions about what will happen to Pfizer’s other sickle cell disease treatment in development, GBT-601. 

That oral drug, which Pfizer also acquired through the Global Blood Therapeutics deal, is seen as a successor to Oxbryta.

Feel free to send any tips, suggestions, story ideas and data to Annika at annikakim.constantino@nbcuni.com.