In a significant stride toward refining endovascular interventions for patients with severe vascular disease, the Medical University of Graz has officially enrolled the first patient in the DEEPER CHALLENGE study. This investigator-initiated clinical trial is set to rigorously evaluate the efficacy and mechanical impact of Reflow Medical’s Spur Peripheral Retrievable Scaffold System when used in conjunction with a drug-coated balloon (DCB) for the treatment of chronic limb-threatening ischaemia (CLTI).
By focusing on one of the most challenging demographics in vascular medicine—patients with diabetes and those suffering from end-stage renal disease (ESRD)—the study promises to yield critical data that could reshape treatment protocols for high-risk populations.
Main Facts: The DEEPER CHALLENGE Initiative
The DEEPER CHALLENGE study is a single-centre, investigator-initiated, single-arm prospective trial designed to address a persistent clinical dilemma: the mechanical failure of vessels following angioplasty in below-the-knee (BTK) interventions.
The core of the investigation revolves around the Spur Peripheral Retrievable Scaffold System, a specialized device engineered to provide mechanical support to the vessel wall during the critical post-angioplasty period. Unlike permanent stents, the "retrievable" nature of the Spur scaffold allows physicians to stabilize the vessel lumen without leaving behind a long-term metallic implant, which is often associated with late-stage complications such as chronic inflammation or structural fracture in the dynamic environment of the lower leg.
The trial is set to enroll up to 40 patients. A defining feature of this study is its commitment to inclusivity and representation. The cohort will be evenly split between two distinct groups:
- Patients with diabetes mellitus.
- Patients with end-stage renal disease (ESRD) who have undergone haemodialysis for at least six months.
Furthermore, the study mandates a gender-balanced approach, requiring that women comprise at least 50% of each cohort—a pioneering step toward rectifying the historic under-representation of women in cardiovascular and peripheral artery disease (PAD) clinical research.
Chronology: A Trajectory of Innovation
The launch of the DEEPER CHALLENGE study represents the culmination of years of development in retrievable scaffold technology.
- Pre-Clinical Development: Reflow Medical focused on creating a device that could effectively combat the "recoil" phenomenon, where a blood vessel snaps back to its narrowed state immediately after the balloon is deflated.
- Regulatory and Design Milestones: The company refined the Spur system to work in tandem with current standards of care, specifically drug-coated balloons, which deliver anti-proliferative medication to prevent vessel restenosis.
- Study Design Phase: Throughout 2025, the team at the Medical University of Graz, led by clinical experts in angiology, designed the protocol for the DEEPER CHALLENGE to ensure it met the highest standards of evidence-based medicine.
- July 2026 – Enrolment Commencement: The official enrollment of the first patient marks the transition from design to active data collection, setting the stage for 12 months of intensive monitoring.
- Parallel Innovation: The study arrives on the heels of Reflow Medical’s broader push into scaffold technology, including the July 2024 initiation of a pilot study for the "Spur Elute" (Coronary Sirolimus-Eluting Retrievable Scaffold System), demonstrating the firm’s commitment to both peripheral and coronary applications.
Supporting Data: Why "Early Vessel Recoil" Matters
In the world of vascular surgery, the success of a procedure is often decided within the first few minutes after the balloon is withdrawn. "Early vessel recoil" is the primary endpoint of the DEEPER CHALLENGE study, measured by angiography within 15 minutes of the procedure.
The Mechanical Challenge
When an interventionalist treats a blocked artery below the knee, the vessel is often calcified or prone to spasm. Upon deflation of the angioplasty balloon, the vessel often lacks the structural integrity to remain open, leading to "recoil." This recoil reduces the efficacy of the drug-coated balloon, as the medication cannot be effectively delivered if the vessel wall is not optimally apposed to the balloon surface.
The Methodology
By using the Spur scaffold to hold the vessel open during the drug-delivery phase, researchers hope to demonstrate a significant reduction in immediate recoil. The study will track several secondary outcomes:
- Hemodynamic Success: Measured at 30 days to ensure blood flow remains restored.
- Major Adverse Limb Events (MALE): A critical safety metric tracking potential amputations or further procedures.
- Mortality and Durability: Longitudinal tracking up to 12 months to assess if the intervention provides a durable solution for patients who otherwise have very limited surgical options.
Official Responses: Voices from the Field
The significance of this trial has been echoed by both the clinical leadership and the industry stakeholders involved.
Professor Marianne Brodmann, head of the angiology division at the Medical University of Graz and co-investigator of the study, highlighted the importance of the trial’s demographic focus. "Patients with end-stage kidney disease or diabetes are often under-represented in CLTI studies, despite facing higher risks of restenosis and limb-threatening ischaemia," she stated. "Additionally, females are systematically under-represented in most medical research. By focusing our inclusion criteria on these specific groups, we are not only testing the device but also gathering vital data on the vessel’s immediate mechanical response in these complex, high-risk populations."
From the industry side, Dejan Ilic, Vice President of Global Marketing at Reflow Medical, emphasized the collaborative nature of the effort. "We are pleased to support this investigator-initiated study led by the Medical University of Graz, which addresses important questions in below-the-knee disease. The study reflects our continued commitment to collaborating with physicians to advance clinically driven research in high-risk patient populations. Our focus remains on creating solutions that provide tangible benefits to patients who face the highest risk of limb loss."
Implications: The Future of CLTI Treatment
The implications of the DEEPER CHALLENGE study extend far beyond the 40 participants involved. If the study successfully demonstrates that the Spur Peripheral Retrievable Scaffold System reduces early vessel recoil and improves outcomes in diabetic and dialysis patients, it could lead to a paradigm shift in how peripheral artery disease is managed.
1. Standardizing Care for High-Risk Groups
Currently, patients with ESRD and diabetes are notoriously difficult to treat because their vasculature is prone to heavy calcification and poor healing. If a retrievable scaffold can stabilize these vessels without the long-term risks associated with permanent implants, it could become the new standard of care for this difficult-to-treat population.
2. The Power of "Retrievable" Technology
The move toward retrievable scaffolds addresses the "leave-nothing-behind" philosophy that is gaining momentum in endovascular therapy. By removing the metal after it has served its purpose, surgeons reduce the risk of future interventions being complicated by previously placed stents.
3. Improving Gender Parity in Clinical Trials
By mandating a 50% enrollment rate for women, this study serves as a benchmark for future cardiovascular trials. It underscores the reality that vascular disease impacts women differently than men, and that clinical solutions must be tested across diverse physiological profiles to be truly effective.
4. Economic and Health System Impact
For healthcare systems, the potential to reduce "major adverse limb events" (MALE) is a major economic driver. By decreasing the rate of repeat interventions and preventing amputations, the Spur system could significantly reduce the long-term healthcare burden associated with the complications of chronic limb-threatening ischaemia.
Conclusion
As the DEEPER CHALLENGE study progresses, the medical community will be watching closely. By bridging the gap between mechanical intervention and pharmacological therapy, and by prioritizing the most vulnerable and under-studied patient demographics, the researchers at the Medical University of Graz are taking a bold step toward a future where limb salvage is more effective, more inclusive, and more durable. The results of this study are expected to influence clinical guidelines and provide the evidence base needed to bring sophisticated, patient-centered care to the forefront of vascular medicine.
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