Pfizer’s Oxbryta Departure Could Accelerate Trials of Competing Experimental Sickle Cell Drugs, Analysts Suggest

By Kashish Tandon and Christy Santhosh

Pfizer’s recent decision to withdraw its treatment for sickle cell disease due to death risks could accelerate trials of competing experimental therapies, according to Wall Street analysts.

Oxbryta, one of several treatments for the condition, is primarily used for patients with mild to moderate symptoms. This drug was granted accelerated approval in the U.S. back in 2019, contingent on conducting further trials to substantiate its benefits.

In July, the European Medicines Agency raised concerns about fatalities in two of these trials. Following a meeting to assess the data, the agency expressed significant safety concerns and suggested an immediate suspension of its approval.

The U.S. Food and Drug Administration is currently reviewing safety data from postmarketing clinical studies of Oxbryta and will also evaluate real-world registry studies. The agency plans to communicate any additional findings that arise from this review.

Several Wall Street brokerages indicated that the withdrawal could create an urgent need to expedite trials for rival drugs targeting this inherited condition, such as mitapivat from Agios Pharmaceuticals and pociredir from Fulcrum Therapeutics.

Enrollment challenges have hampered early-stage trials for Fulcrum, according to analysts from Leerink. Conversely, for Agios, this situation may pressure regulators to accelerate their review process, as noted by Piper Sandler analysts.

If mitapivat demonstrates efficacy in reducing painful episodes associated with sickle cell disease, the regulatory review process may become more streamlined, particularly given the heightened demand from patients unable to access Oxbryta, remarked Piper Sandler’s Christopher J. Raymond.

Following the announcement, shares of Agios initially surged by 4% before retreating, while Fulcrum’s stock experienced a jump of over 17%.

Recently approved gene therapies, including those from bluebird bio and Vertex Pharmaceuticals in collaboration with CRISPR Therapeutics, are intended for patients with the severe form of sickle cell disease.

With the removal of Oxbryta, the majority of patients with mild to moderate symptoms will likely rely on hydroxyurea, a chemotherapy medication, according to Stifel analyst Dae Gon Ha.

Sickle cell disease impacts an estimated 100,000 individuals in the U.S., predominantly affecting the Black population.

This withdrawal represents yet another challenge for Pfizer and its CEO Albert Bourla, as the company faces investor dissatisfaction amidst plummeting sales of its COVID vaccines and other drugs, a lackluster launch of a vaccine for respiratory syncytial virus (RSV), and disappointing results from an obesity treatment in development.

On Thursday, Pfizer’s shares dipped slightly, now trading at approximately half of the peak values seen during the pandemic.

Oxbryta was a central component of Pfizer’s $5.4 billion acquisition of Global Blood Therapeutics in 2022, part of several strategic deals funded by the financial boost during the pandemic. The company also acquired two other experimental treatments for sickle cell disease, both still undergoing clinical trials.

In sickle cell disease patients, red blood cells take on a sickle or crescent shape, which can result in strokes, organ damage, early mortality, and severe pain crises.