Pfizer’s CD47 nightmare deepens

Pfizer’s $2.3bn takeover of Trillium was already looking misguided, and now it’s taken another blow. A phase 2 trial of the Trillium-originated CD47-targeting project maplirpacept, in relapsed/refractory DLBCL, has been terminated due to difficulties recruiting patients, its clinicaltrials.gov listing has revealed. A couple of other Pfizer-sponsored studies are still recruiting, including one testing an Elrexfio combo in relapsed multiple myeloma, but hopes cannot be high after various trial discontinuations over the past year – even after Pfizer’s insistence at a 2024 R&D day that maplirpacept was still a key project. Meanwhile ontorpacept, another anti-CD47 asset from Trillium, no longer features on Pfizer’s pipeline. The company has put most of its CD47 trial terminations down to administrative reasons, and has noted a lack of toxicity concerns. This could be in response to the increased risk of death seen with Gilead's rival project, magrolimab, which led to that being canned first in haematologic cancers, then soon after in solid tumours. Others still persevering with CD47 include ALX, which continues to develop its contender evorpacept despite various setbacks, most recently in gastric cancer. 

Notable studies of Pfizer’s anti-CD47 assets

Source: OncologyPipeline & clinicaltrials.gov.