The experimental monoclonal antibody bentracimab, which reverses the antiplatelet effects of ticagrelor, appears to be heading toward regulatory approval, on the basis of an interim analysis of the phase 3 REVERSE-IT trial.
“Rates of effective hemostasis were adjudicated as good or excellent in more than 90% of cases with no drug-related serious adverse events or allergic or infusion-related reactions,” reported Deepak L. Bhatt, MD, at the American Heart Association scientific sessions.
The interim analysis of this nonrandomized, single-arm study was requested by the Food and Drug Administration, which is considering a conditional accelerated approval of bentracimab (formerly PB2452) if efficacy and safety are established.
Upon administration, bentracimab binds to free ticagrelor so that ticagrelor cannot bind to the P2Y12 platelet receptor. This interrupts one of the key steps in the pathway of platelet aggregation.
REVERSE-IT is still enrolling patients. This interim analysis was conducted with the first 150 patients who met eligibility criteria and were treated. Of these, 142 patients were enrolled for an urgent surgical indication and 8 for a major bleeding indication. After some exclusions for lack of urgency and reclassifications following adjudication, there were 113 surgical cases and 9 major bleeding patients evaluable for hemostasis.
Platelet Function Assays Test Reversal
On the primary reversal endpoint, which was restoration of activity on the proprietary platelet function assays Verify Now and PRUTest, a rapid restoration of platelet function was achieved in both surgical and major-bleeding patients. Platelet reactivity climbed to near normal levels within 10 minutes of administration, and peak effects were sustained through the first 24 hours after administration.
On the basis of the platelet function assays, the pattern of response to bentracimab was “very similar in the surgical and bleeding patients,” reported Bhatt, executive director of interventional cardiovascular programs at Brigham and Women’s Health, Boston.
The effect was also consistent across a broad array of prespecified subgroups, including stratifications by age, renal function, time from last dose of ticagrelor, race, and the presence of comorbidities, such as diabetes, renal dysfunction, hypertension, and history of MI.
Hemostasis Documented in All but One Patient
Adjudicated hemostasis was achieved in 100% of the 113 urgent surgical patients evaluated. In the nine major bleeding patients, six achieved excellent hemostasis and one achieved good hemostasis. One had poor hemostasis, and one was unevaluable.
Platelet rebound following bentracimab administration, measured by mean platelet volume, was not observed.
There were no serious adverse events, allergic reactions, or serious infusion-related reactions associated with the administration of bentracimab, Bhatt said.
While Bhatt acknowledged that the number of patients in the major-bleeding subgroup was small, he noted that the reduction in platelet reactivity relative to baseline was still significant. In addition, he characterized urgent surgery as “an excellent model of bleeding” and pointed out the consistency of results in the surgical and major-bleeding groups.
The interim results are also consistent with phase 1 data published 2 years ago, and with the subsequent phase 2 studies. All of these data are now under regulatory review both in the United States and in Europe, according to Bhatt.
No Good Current Options for Reversal
Evidence of efficacy and safety is encouraging, because current options for urgently reversing ticagrelor are “disappointing,” according to the invited discussant Gilles Montalescot, MD, PhD, professor of cardiology, Pitié-Salpêtrière Hôpital, Paris.
“Platelet transfusion has some value for clopidogrel and prasugrel, but it does not work for ticagrelor,” said Montalescot, referring to two other P2Y12 inhibitors. Substantiating the need for a reversal agent, he identified several other strategies that have proven ineffective, such as desmopressin and sorbent hemadsorption.
Overall, Montalescot acknowledged the need for a highly effective ticagrelor reversal agent, but he did have some criticisms of REVERSE-IT. For one, he was not convinced about the design.
“What was unethical in having a control group?” he asked, suggesting that it was feasible and would have addressed issues of relative efficacy and safety.
For example, the authors concluded that none of the thrombotic events were likely to be treatment related, but “four events occurred immediately after reversal without an alternate explanation,” Montalescot pointed out. “Was this a signal or background noise?”
Nevertheless, he agreed that the interim phase 3 data are consistent with the previously reported phase 2 studies, and he reiterated that a strategy to reverse ticagrelor’s effects is an important unmet need.
Bhatt has a financial relationship with a large number of pharmaceutical companies, including PhaseBio, which provided funding for the REVERSE-IT trial. Montalescot reported financial relationships with Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, Boston Scientific, Bristol-Myers Squibb, Cell-Prothera, CSL-Behring, Europa, Idorsia, Servicer, Medtronic, Merck Sharpe & Dohme, Novartis, Pfizer, Quantum Genomics, and Sanofi-Aventis.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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