Pfizer takes pipeline blow as it abandons cardiomyopathy drug

Pfizer has stopped development of a drug to treat cardiomyopathy caused by a rare form of heart disease, after it proved ineffective in a phase 3 trial.

PF-07265803 – a p38 mitogen-activated protein kinase (MAPK) antagonist also known as emprumapimod – was being tested as a treatment for symptomatic dilated cardiomyopathy (DCM) due to a mutation in the LMNA gene in the REALM-DCM trial.

LMNA codes for two proteins, lamin A and C, which form structural components in cells. When mutations occur it can lead to a wide range of disease, called laminopathies.

One manifestation can be dilated cardiomyopathy, where the muscles of the heart become thin and stretched, making it harder to pump blood to the rest of the body, which can lead to heart failure. There are no therapies for LMNA-related DCM.

REALM-DCM enrolled adults with LMNA mutations and symptomatic DCM and an implanted defibrillator, with the main efficacy endpoint their ability to complete a six-minute walk test compared to placebo after 24 weeks' treatment.

The decision to stop development of PF-07265803 comes after of interim futility analysis concluded the study was unlikely to meet its primary endpoint. It was supposed to enrol 200 subjects and generate results in 2014.

"This development confirms the complexity of advancing new treatments for rare cardiovascular diseases and the need to further increase knowledge in this space," said Chris Boshoff, Pfizer's chief development officer for oncology and rare disease therapies.

Patients in REALM-DCM will now stop study medication and complete any necessary follow-up evaluations, under the guidance of study site investigators.

DCM is one of the leading causes of heart failure worldwide, and accounts for about 30% of all heart failure hospitalisations in the US, as well as being the most common reason for needing a heart transplant. One study found that around 7.5% of DCM patients had LMNA mutations.

Pfizer acquired PF-07265803 went it bought Array BioPharma in 2019 for $11.4 billion, a deal focused mainly on Braftovi (encorafenib) and Mektovi (binimetinib) for BRAF-positive colorectal cancer.

If approved, the drug would have slotted into its portfolio alongside Vyndaqel/Vyndamax (tafamidis), used to treat cardiomyopathy caused by another rare disease, transthyretin-mediated amyloidosis (ATTR), which pulled in $1.2 billion in the first six months of 2022.