PhaseBio Pharmaceuticals, Inc. PHAS reported interim data from the ongoing phase III REVERSE-IT study evaluating its lead product candidate bentracimab to reverse the antiplatelet effects of blood thinner drug ticagrelor in surgical and bleeding populations.

Ticagrelor is a blockbuster drug developed by AstraZeneca AZN and marketed under the brand name Brilinta/Brilique for cardiovascular treatment.

For the third quarter, AstraZeneca reported Brilinta/Brilique sales of $375 million, down 18% year over year primarily due to the impact of the COVID-19 pandemic (reflecting fewer elective procedures) and pricing pressure from the volume-based procurement program in China. AstraZeneca reported that the drug has already generated sales of $1.12 billion from the beginning of the year till September-end 2021.

The REVERSE-IT study evaluated bentracimab in 150 patients with the need for urgent surgery or an invasive procedure or experiencing uncontrolled major or life-threatening bleeding.

The study achieved its primary endpoint of immediate and sustained reversal of the antiplatelet effects of ticagrelor, with patients showing a 135% reduction in platelet inhibition within 5-10 minutes after initiation of the bentracimab infusion and sustaining the effects of the drug through all timepoints over 24 hours. Further, 90% of the eligible patients achieved effective hemostasis, the study’s co-primary endpoint of clinical hemostasis, within 24 hours of initiation of bentracimab infusion.

Yet, PhaseBio reported that 91% of enrolled patients administered the drug experienced treatment-emergent side effects. While the most common side effect was pain associated with surgical procedures, cardiac and metabolic disorders such as atrial fibrillation, sinus tachycardia as well as electrolyte abnormalities were also reported. Four patients enrolled in the study died, which the company said were not related to treatment with the drug. Eight patients experienced thrombotic events, though none of the cases were related to treatment with bentracimab.

Shares of PhaseBio were down 18.4% yesterday, most likely due to the large patient population experiencing the side effects of bentracimab. In fact, shares have declined 10.1% so far this year in comparison with the industry’s 14.6% decline.

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The phase III study was initiated on the basis of data from phase I and phase II studies on bentracimab, which have also demonstrated immediate and sustained reversal of the antiplatelet effects of ticagrelor. PhaseBio expects to submit a biologics license application with the FDA seeking approval for bentracimab in mid-2022.