Disappointing data lead Pfizer to drop heart drug acquired as part of $11B deal

by Bailey Amber
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When Pfizer acquired Array Biopharma for $11.4 billion three years ago, the focus was its FDA-approved cancer drugs. The buyout also came with drug candidates in development for other diseases, and it’s the end of the road for one of them.

Pfizer is stopping work on PF-07265893, a drug that had reached Phase 3 testing for symptomatic dilated cardiomyopathy, a type of heart muscle disease. The oral small molecule was designed to address forms of the disease that stem from a particular genetic mutation.

Symptoms of dilated cardiomyopathy include fatigue and shortness of breath. The condition, which has no specific FDA-approved treatment, can also lead to heart failure that can become fatal. The Pfizer drug is designed to block a pathway associated with the disease’s progression. In an open-label Phase 2 test, results showed improvement measured according to a test that measures the distance patients can walk in the span of six minutes.

The six-minute walk test was also the main goal of the placebo-controlled, 24-week Phase 3 study of PF-07265893. Secondary goals include assessing the six-minute walk at weeks four and 12, and assessing a change in score according to a cardiomyopathy questionnaire. Pfizer said late Wednesday that an interim analysis found the study was unlikely to meet its main goal. The company did not release specific findings of that analysis, but said that the decision to discontinue work on the drug was not based on any safety concerns. More detailed data from the clinical trial will be presented at future medical meetings, the company said.

“This development confirms the complexity of advancing new treatments for rare cardiovascular diseases and the need to further increase knowledge in this space,” Chris Boshoff, Pfizer’s chief development officer for oncology and rare disease, said in a prepared statement.

The Phase 3 trial for PF-07265803 started under Array Biopharma. That Boulder, Colorado-based company had commercialized two cancer drugs, Braftovi and Mektovi, as a combination treatment for melanoma characterized by a particular genetic mutation. Pfizer’s 2019 acquisition of Array followed positive Phase 3 data testing the drug combo in colorectal cancer.

Braftovi won an additional approval in colorectal cancer in 2020. Under Pfizer, neither Braftovi nor Mektovi have become big sellers. Braftovi accounted for $187 million in revenue last year, according to Pfizer’s 2021 annual report. Mektovi accounted for $155 million in sales.

Pfizer said it is working with regulators, clinical trial investigators, and community groups to wind down the PF-07265893 clinical trial.

Photo: Dominick Reuter/AFP, via Getty Images

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