ACC: AstraZeneca's Brilinta taken solo is less risky than aspirin combo

AstraZeneca has put a lot of resources in its blood thinner Brilinta, but will all those clinical data pay off? (AstraZeneca)

AstraZeneca has put a lot of resources behind its aging blood thinner Brilinta, hoping to keep the anticoagulant's place in doctors' minds fresh for years to come. With a suite of new data and analysis in stent patients, solo Brilinta has shown it matches combo therapy efficacy-wise, while cutting the risk of bleeding.

Solo Brilinta showed similar rates of major cardiovascular events after 12 months but reduced bleeding episodes compared to Brilinta-plus-aspirin, the standard of care. That's according to two studies presented Monday at the American College of Cardiology scientific sessions.

The first set of analyses looked at patients with diabetes or complex heart disease who had received a coronary stent, using data drawn from the 9,000-patient phase 4 Twilight study.

Just 4.5% of patients with diabetes showed significant bleeding on Brilinta alone after three months of receiving aspirin following a stent procedure. In the standard-of-care dual anti-platelet arm (Brilinta and aspririn), 6.7% of patients suffered significant bleeding episodes. 

Solo Brilinta also edged the Brilinta-aspirin combo in terms of reducing CV deaths, strokes or heart attacks in those diabetes patients—4.5% to 5.9%, respectively—but the results weren't significantly significant. 

In complex CV disease patients at a high risk of adverse events, the solo therapy advantage was larger: 4.2% of patients treated with Brilinta alone showed significant bleeding episodes compared with 7.7% in the Brilinta-aspirin arm. Severe or fatal bleeding occurred in 1.1% of patients receiving solo Brilinta compared with 2.6% of those treated with the combo.

In a separate trial, dubbed Tico, solo Brilinta dropped the rates of significant bleeding and matched rates of major CV events after 12 months in patients with acute coronary syndrome (ACS) who had undergone a coronary stent procedure.

In the solo Brilinta arm, 3.9% of ACS patients had a heart attack, stroke, blood clot inside a stent, died or needed a second surgery compared with 5.9% of patients in the combo arm—a statistically significant difference.  Major bleeding occurred in 1.7% of solo Brilinta patients compared with 3% of combo patients. 

AstraZeneca's extensive clinical program for Brilinta has produced a wealth of data on the aging blood thinner in recent years, but analysts are concerned that the British drugmaker's sunk costs into the $1.5 billion-per-year med won't pay off in the long run.  

RELATED: AstraZeneca has dumped billions into Brilinta R&D, but will it ever pay off?

In January, EvaluatePharma said AstraZeneca will likely never turn a profit on Brilinta with an estimated $5.4 billion in total R&D costs, generics expected to hit the market in 2024 and marketing expenses swallowing up any increase in the drug's already disappointing sales.

Much of that R&D expense has been tied to AstraZeneca's Parthenon program, Evaluate reported, which has turned out a suite of trial data, including top-line results from the phase 3 Thales study released in January.

Parthenon—and its six outcomes trials for Brilinta—racked up $3.7 billion in R&D costs as of January with an additional $1.7 billion tied up in more than 80 investigator-sponsored trials, Evaluate said. Of the six Parthenon studies, two have led to label updates, while another two were called "clear failures" by Evaluate.

In the most recent Parthenon trial—a phase 3 called Thales—twice-daily Brilinta on top of aspirin significantly cut the risk of stroke or death over aspirin alone in patients who had suffered a stroke or transient ischemic attack and started treatment within 24 hours, according to top-line data released in January.

However, patients also posted a higher bleeding risk than those in the control arm, a problem that has plagued the drug in past trials. With further data set to be presented at an upcoming medical conference, Evaluate couldn't declare the study a clear winner without understanding the scope of Brilinta's efficacy.