Pq Bypass Inc. received breakthrough device designation from the FDA for its Detour system, the first to permit fully percutaneous femoropopliteal bypass to treat extremely long, complex blockages in the superficial femoral artery (SFA).

“This designation is a major milestone for Pq Bypass, and we expect this technology to change the paradigm for complex SFA treatment in the way EVAR and TAVR changed the paradigm for aortic repair,” said Rich Ferrari, chairman and CEO of Pq Bypass.

An estimated 20 million people in the U.S. have lower limb peripheral artery disease (PAD) and approximately 5 million have the severe form of the disease that the Detour system addresses.

“For patients with SFA blockages who have debilitating pain or tissues loss, there are two options for treatment today: a minimally invasive procedure with a guidewires, balloons, and stents or open femoropopliteal surgery,” Heather Simonsen, general manager of Pq Bypass told BioWorld. “The Detour system is designed for patients who are candidates for open fempop bypass, which is the current guideline recommendation for long, complex lesions.”

The target candidate for the Bypass system has the most complex kind of lesions. Where clinical trial data for long lesions, usually look at those that are just 10 cm to 15 cm, while a typical Detour-type lesion might start at 27 cm and would typically be 35 cm to 40 cm, Simonsen said. Further, while even 30 cm of a partially blocked SFA could possibly be treated with existing minimally invasive tools, the Bypass system aims to provide a minimally invasive option for patients who have severe calcification or 100% blockage in 15 cm to 20 cm of the lesion’s length.

“Essentially, that really limits options for minimally invasive surgery,” Simonsen noted. “There are few experts in the world who could address this kind of lesion [without open surgery] and could arrange a channel, and if they did, it would get totally occluded in six months.”

Open surgery has the advantage of being very durable; particularly if a vein is harvested, the bypass lasts, Simonsen said. On the downside, open surgery requires a four- to seven-day hospitalization and weeks or months of recovery time. In contrast, 100% of the procedures in the DETOUR2 trial of the Detour system in the U.S. have taken place in outpatient facilities and patients went home the same day. “These patients had the same recovery time as seen in an angioplasty procedure, with little or no down time,” Simonsen added.

The Detour system

The Detour system uses three components: a stent graft, a crossing device, and a snare. Together, the system creates a bypass from the occluded artery into a vein and back into the artery. Unlike harvesting a vein, the system allows the vein to continue working. “We only occupy a portion of the vein. The bypass is made with stent grafts to create a tube within the vein; it’s a unique procedure design.”

The affected area is accessed through the femoral artery. Just above the blockage, the crossing devices makes a channel from the artery into the vein and then back again below the lesion. The snare is used to pull guidewires into position to deliver the stents and create the bypass path within the vein. Blood from the artery is redirected down through the bypass and resumes its regular course beyond the blockage.

“Two things are really compelling about the Detour procedures. First, Detour is analogous to EVAR for abdominal and thoracic procedures, which used to be open surgeries only before the technology developed and changed treatment completely. The same is true with heart valves. It’s surprising to me that we’re in 2020 and we hadn’t figured this out for peripheral artery disease until now.”

“Second, most devices have been tested on much shorter, less complex lesions,” Simonsen noted. “As we move to more complex patients, there hasn’t been a good solution until now.”

Clinical trials

Pq Bypass has two clinical trials in process: TORUS2 and DETOUR2. Both trials use the same stent graft, which is the first new stent graft for SFA brought to the U.S. in the last 15 years. The stent is designed specifically to withstand the complexity, forces, and torsion associated with more severe SFA blockages and to continue to function in a critical part of the body. In addition, it has a novel design on the ends that mitigate against failure on the edges and to try to reduce restenosis.

TORUS2 aims to include 188 patients with somewhat complex symptomology, but without the severity seen in Detour patients. The trial started enrollment in early 2020 and currently has 72 participants. The procedure uses the stent graft by itself.

DETOUR2 uses all three components of the Detour system and has a sample size of 202 patients, with all but 15 enrolled. The pandemic has not been a significant factor in participation, Simonsen said. “We haven’t seen as much of a slowdown as we expected in enrollment in this study because the patients are in much worse shape and can’t put off the procedure for a few months.”