EnligHTN IV Renal Denervation Study Called Off

December 09, 2013

ST PAUL, MN – The EnligHTN IV study (St Jude Medical, St Paul, MN), testing the multielectrode renal-denervation system in patients with resistant hypertension, has been stopped almost before it even began. The trial, which was announced in June and began enrolling a small number of patients this fall, was canceled because of concerns about slow enrollment.

To heartwire , Denise Perkins-Landry, a spokesperson for St Jude Medical, said the decision to discontinue the study was based on "anticipated recruitment challenges" and is not the result of any safety or efficacy issues with the device. "A US clinical trial for EnligHTN remains a very high priority for St Jude Medical, and we will be working with the FDA to develop a new protocol that will address anticipated enrollment challenges," she stated in an email.

The full results of the SYMPLICITY HTN-3 trial, a study similar to the EnligHTN IV study, which is sponsored by Medtronic (Minneapolis, MN), are expected in early 2014. While neither device is approved for clinical use in the US, it is expected that the Medtronic renal-denervation system will be first. As a result, it might be difficult to enroll patients to a sham procedure if there is another commercially available system for treating resistant hypertension, according to St Jude.

EnligHTN IV was to be a randomized, single-blind, controlled study with patients randomized from as many as 80 clinical centers in the US and Canada. It was intended to show the safety and effectiveness of the renal-denervation system in the reduction of systolic blood pressure in 590 patients with an office blood pressure >160 mm Hg despite taking three or more antihypertensive medications, including a diuretic.

Abrupt Decision to Stop the Study

Dr William White (University of Connecticut Medical Center, Farmington), one of the cochairs of the EnligHTN IV steering committee, told heartwire the decision to cancel the study was made just last week. In fact, there were clinical centers already up and running in terms of enrollment, although these were pilot centers where any "bugs could be worked out." The meeting for training investigators participating in the trial was scheduled for Saturday in Chicago, IL, although that is now off.

"In the grander scheme of things, I can tell you that the decision was not made because of any problem with the catheter or any safety issues," said White. "Outside the US, the development is continuing as planned, but the biggest concern is that it might be very difficult, if not impossible, to continue doing a sham-controlled study a year from now if there were a commercially available renal-denervation catheter in the US, which there very well could be with Medtronic."

Still, White said that it's not even known if the SYMPLICITY HTN-3 study is positive or if the FDA will be satisfied with the trial and its outcomes. He said a lot of assumptions are being made by St Jude Medical in stopping the trial, and it could turn out to be a bad decision. In addition, reimbursement remains an open question.

"Commercially available doesn't mean there's going to be a payer," White told heartwire . "If that happens, it will be doubly unfortunate for the patients that are out there because they might be willing and able to go into a clinical trial but they won't have that opportunity."

As a scientist, White said that he would have preferred the trial be pursued, regardless of what happens with Medtronic. He believes the EnligHTN catheter is "outstanding," as it has multiple electrodes to enable physicians to thoroughly ablate the renal arteries within a couple of minutes. "The clinical scientist in me would have preferred that we go ahead as planned," he said. "I think we would have gained a great deal of knowledge. And just because one study shows a p value of 0.05 doesn't mean a second study will."

The Medtronic SYMPLICITY renal-denervation system was launched in 2010 and is available in parts of Europe, Asia, Africa, and South America. The first-generation EnligHTN device has had CE Mark approval in Europe since 2012 while the updated second-generation system with multiple electrodes received European approval this past summer.

News of the halting of EnligHTN IV was first reported by Wells Fargo analyst Larry Biegelsen.

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