Pfizer has called time on a phase 2 trial of its CXCR5 antibody in an autoimmune blood disorder, with the company tight-lipped on whether this marks the end of the road for the asset.
The Big Pharma had been evaluating the therapy, dubbed PF-06835375, in a phase 2 study of 61 patients with primary immune thrombocytopenia (ITP) that kicked off in 2022, according to the federal trials register.
However, Pfizer confirmed to Fierce on Monday that this study had been terminated “due to a business decision.”
“The decision to terminate the trial was not based on any safety concerns,” a spokesperson pointed out.
At time of publication, PF-06835375 remained listed on Pfizer’s website for both ITP and lupus. A phase 1 study in lupus wrapped up in 2022, according to the trials database.
ITP is an autoimmune disorder characterized by a low platelet count. Novartis was at one point evaluating its B-cell-depleting antibody ianalumab—recently approved as Fabhalta to treat immunoglobulin A nephropathy—as a potential treatment ITP. But the therapy struggled to demonstrate a benefit in the clinic for this indication.
When contacted by Fierce, Pfizer wouldn’t confirm whether all work on PF-06835375 has been halted, and whether the company has any other plans to explore C-X-C chemokine receptor type 5 (CXCR5) as a mechanism.
CXCR5 is found in blood cancers such as diffuse large B-cell lymphoma and mantle cell lymphoma chemokine receptor. However, there is little expression in normal tissue, which has led some drug developers to explore its potential.
Vincerx Pharma had at one point been planning to take an anti-CXCR5 ADC into the clinic to treat B-cell malignancies, but that ambition was scrapped due to cash constraints.
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