Preventing Post-Thrombotic Syndrome after Deep Vein Thrombosis with Perivascular Anti-Inflammatory Agent Delivery - PROJECT SUMMARY
Post-thrombotic syndrome (PTS) is a chronic debilitating condition characterized by limb swelling and discomfort,
hyperpigmentation, skin ulcers, and impaired quality of life. It occurs within 2 years of deep vein thrombosis
(DVT) treatment in 50-60% of patients with iliofemoral thrombosis and in 30-50% of all DVT patients regardless
of thrombosis location (1). Even with pharmacological catheter-directed thrombolysis (PCDT) or catheter-
directed thrombectomy (CDT) as used in the most recent clinical trials (e.g. ATTRACT, CaVenT and CAVA),
there remains a 40-50% rate of PTS. In the NHLBI/NIH-funded ATTRACT randomized trial, for example, PCDT
did not reduce the incidence of PTS over 24 months, compared to control anticoagulation alone. In subgroup
analysis, PCDT conferred reduced moderate-to-severe PTS in iliofemoral DVT (2,3), and no benefit when PCDT
was administered after 8 days post-symptom onset (4). Overall, there remains a clear unmet need to expand the
armamentarium of therapies beyond selective PCDT in reducing the clinical and economic burden of PTS.
Post-thrombotic syndrome evolves from an interplay of multiple factors: fibrotic vein wall stiffening leading to
damaged venous valves and subsequent valvular reflux, and continued obstruction of venous outflow due to
thrombus persistence, leading to venous hypertension. Each of these outcomes can arise from venous
inflammation, which is now considered a key in the process of deterioration to PTS after DVT treatment (5,6).
Hypothetically, drugs with anti-inflammatory properties may therefore have the ability to prevent PTS (7-10). It
is further plausible that anti-inflammatory therapy may be more efficacious if delivered locally,
concomitantly with catheter-directed clearance of thrombosis (e.g. PCDT/CDT).
Mercator MedSystems is the pioneer in local perivascular drug delivery, particularly with anti-inflammatory
agents such as dexamethasone (a powerful, inexpensive glucocorticoid). Via the Bullfrog® Micro-Infusion
Catheter platform (currently available to treat vessels of 2-8 mm diameter), Mercator is developing a device to
treat the larger iliofemoral veins, which will have diameter up to 20 mm. Localized anti-inflammatory agent
delivery is proposed as a novel therapy to reduce the progression to PTS after DVT treatment.
In this Phase I STTR proposal, Aim 1 will investigate the anti-inflammatory capability of perivascular
dexamethasone delivery in a mouse model of DVT, and Aim 2 will engineer a larger Bullfrog® device for
human use in up to 20 mm-diameter veins. After completion of this Phase I project, the central
hypothesis of locally delivered anti-inflammatory treatment of the vein wall post-DVT treatment will be
investigated in large animals and human trials in Phase II research.
