ESMINT 2021: COATING study “badly needed” to assess surface modification of flow diverters

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coating study phenox
Laurent Pierot

This year’s Congress of the European Society of Minimally Invasive Neurological Therapy (ESMINT 2021; 8–10 September, Nice, France and virtual) saw details of the COATING (Coating to optimise aneurysm treatment in the new flow diverter generation; phenox) study presented by Laurent Pierot, head of the Department of Radiology at the University Hospital of Reims (Reims, France), who is also the study’s principal investigator. And, while a discussion following this presentation saw questions raised about patient acceptance in the study, attendees were in agreement that it is highly necessary to improve on the current understanding of surface modification in the treatment of intracranial aneurysms.

Pierot began by reporting that the COATING study will assess the phenox Hydrophilic Polymer Coating (pHPC)—which is designed to modify the surface of a flow diverter in order to reduce platelet aggregation, and minimise complications like intra-stent thrombosis and distal emboli without the need for dual antiplatelet therapy (DAPT) alongside these devices.

This multicentre, prospective, randomised controlled trial (RCT) will therefore compare the endovascular treatment of unruptured or recanalised intracranial aneurysms using a bare p64/p48-MW flow modulation device (phenox) with DAPT, and a coated p64/p48-MW-HPC device (phenox) with single antiplatelet therapy (SAPT). The primary hypothesis of the trial is that the HPC-coated device is non-inferior to the bare device in the treatment of intracranial aneurysms, with the secondary hypothesis being that the coated option is superior to the bare one for the same indication.

Pierot reported that the primary endpoint of the COATING study will be the number of diffusion-weighted imaging (DWI) lesions—visualised via magnetic resonance imaging (MRI)—within 48 hours of the index procedure. Secondary endpoints to evaluate the safety of the approach using a HPC-coated device at up to 365 days post-procedure will include rates of morbimortality, neurological death or major stroke, intracranial haemorrhage, and declining modified Rankin Scale (mRS) scores. Secondary efficacy endpoints will range from rates of successful device deployment, complete aneurysm occlusion, and target aneurysm recurrence, to mean length of hospital stay.

The study will recruit a maximum total of 200 patients—100 per randomisation arm—Pierot continued, with enrolment taking place across 25 European centres including in France, Germany, Italy, and the UK. The planned enrolment period is 12 months per site, and the planned study duration is 36 months per site, with the last patient randomisation expected to occur in Q4 2022 and a final study report scheduled for Q2 2024. Pierot also noted that the first patient was enrolled in the COATING study in France in August of this year.

Randomisation will take place on a 1:1 basis, with patients in both the coated device plus SAPT group and the bare device plus DAPT group receiving routine care alongside their designated treatment approaches. Pierot concluded his presentation by stating that the COATING study is the first multicentre RCT comparing these two specific flow diversion approaches—and will hopefully help to elucidate the effect surface modification can have on the treatment of intracranial aneurysms with these devices.

A discussion following the presentation saw István Szikora, head of the Department of Neurointerventions at the National Institute of Mental Health, Neurology and Neurosurgery (Budapest, Hungary), state that he strongly believes this study is “the only way to go” in order to investigate surface modification in flow diverters, and that it is “badly needed” by the medical community.

He went on, however, to note an ethical concern with the study’s design, that being the fact that it compares a well-established approach for which all the associated benefits and potential complications are known, with an approach about which so little is known, and for which the only tangible benefit for the patient is that they need to take fewer medications following implantation. “If I was a patient,” Szikora continued, “I am pretty sure that I would refuse to enter this study—so, I wonder, psychologically, how you can convince patients to enter the study.”

Pierot responded by stating that this is simply “the principle of randomisation”, and that many novel treatment approaches have had to be investigated from a similarly uncertain starting point in the past. “As of now, we have only randomised one patient, so experience is limited, but I can tell you that patient was accepting without any problem,” Pierot added. He also noted that the study has been approved by an ethical committee and concurred with Szikora that the COATING study is the only way of properly evaluating this new method of treatment.

Speaking to NeuroNews following this ESMINT 2021 session, Pierot stated that SAPT does hold potential benefits for patients compared to DAPT—including lower risks of haemorrhagic complications and earlier occurrence of thrombosis in the aneurysm. He added that SAPT may also enable flow diversion technologies to be deployed in the treatment of ruptured aneurysms as well as unruptured aneurysms, which is another area the COATING study could shed some light on.


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