SWING trial 12-month data: Novel sirolimus DCB shows “great promise” in “challenging” CLTI population

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SWING
Ramon Varcoe at VEITH 2022

The Sundance (Surmodics) sirolimus drug-coated balloon (DCB) has an “excellent” safety profile in a “challenging, real-world, predominantly CLTI [chronic limb-threatening ischaemia] population,” and has a primary patency rate of 80% at 12 months in a per-protocol analysis population. Ramon Varcoe (Prince of Wales Hospital, Sydney, Australia) presented these findings from the SWING first-in-human study at the VEITHsymposium 2022 (15–19 November, New York, USA).

Varcoe, who is co-lead investigator of the trial, added that the research team observed no major amputations, “very low” rates of major adverse events, and “impressive” luminal gain, which was sustained out to six-month angiogram. In addition, Varcoe reported that Rutherford category and the functional outcome measures were improved.

“The Sundance sirolimus-coated balloon is a novel device,” Varcoe informed VEITH attendees. He elaborated: “It has a microcrystalline surface, but also a very sophisticated proprietary excipient, which, rather than using nanoparticles or microreservoirs uses chemistry to deliver the drug into the blood vessel wall and have it retain that much more so than the other devices on the market.”

The presenter noted that SWING is a prospective, multicentre, single-arm feasibility study that looked at patients with stenotic or occluded lesions. The researchers enrolled 35 patients over eight sites in Australia, New Zealand, and also in Europe.

Noting some key inclusion criteria, Varcoe detailed that patients had to be either Rutherford 4 or 5. He added the caveat that Rutherford 3 patients were included, but numbers were capped at 20% of the total cohort. Furthermore, patients had to have de novo or restenotic lesions and at least 50% stenosis by visual estimate of the investigator. They could have up to two distinct lesions in the same or different below-the-knee (BTK) artery, and had to have successfully treated inflow, as well as an unimpaired outflow artery in continuity to the ankle or foot.

The investigators performed both an intention-to-treat and a per-protocol analysis, Varcoe informed the audience. “The reason for that was because [the trial] was conducted over the COVID-19 pandemic period, so we lost seven patients to the primary endpoint of angiography,” he noted, adding that there were also three post-protocol deviations. For these reasons, the research team focused on the 25 patients who had the per-protocol analysis.

The presenter stressed that the patients included represent a “real-world” population, including a high proportion of patients who are smokers and have diabetes, as well as a majority of patients with Rutherford 4 or 5 disease. “They also had high proportions of moderate-to-severe calcification in excess of 18%, and around a third of these patients had total occlusions,” he added.

The study had two primary endpoints. The first was a safety primary safety endpoint—freedom from major adverse limb event (MALE) and perioperative death at 30 days following the index procedure. The primary efficacy endpoint was the rate of late lumen loss at six months, as assessed by quantitative vascular angiography. Both primary endpoints of the SWING trial were achieved, Varcoe revealed.

Varcoe reported that, in the per-protocol population, there were no major amputations, no major reinterventions, and complete freedom from perioperative death, “so it was a safe device”.

The team also saw a rate of all-cause death that was 0%, target lesion amputations were 0%, and a “very low” rate of clinically driven target lesion revascularisation at 8%.

Varcoe added that the minimal luminal diameter at the end of the procedure was “very high”, which he thinks “represents modern-day angioplasty techniques”, and reported a late lumen loss of 1mm at six months—results that compare “very favourably” to other equivalent DCB trials below the knee, he remarked.

As six months, the researchers observed a primary patency of 88.5%. Varcoe noted that primary patency was retained and consistently retained out to 12 months at 80%—a figure that he said is “very good for this part of the vasculature”.

Varcoe added that, “pleasingly,” the team also saw improvement in Rutherford Becker classification, which was sustained and improved out to 12 months. Regarding quality of life, he noted that patient-reported outcome measures were again consistently improved out to that 12-month endpoint.

In closing, Varcoe shared his belief that the Sundance device has “great promise” and “warrants evaluation in a large-scale pivotal trial” based on these latest findings.


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