1. The Novel Importance of Adventitial Therapy for PAD
Christopher D. Owens, MD, MSc
Associate Professor
Division of Vascular and Endovascular Surgery
University of California San Francisco 1

2. Christopher D. Owens, MD
I have no real or apparent conflicts of interest to report.
Off-Label: All drugs I use in early phase studies are off-label.

3. The Tunica Adventitia of a muscular artery
Loosely organized collection of fibroblast, perivascular nerves and microvessels in a collagen-rich ECM
Functional immune surveillance of the artery: Innate and adaptive immunity - inflammatory cells including resident macrophages, mast cells, T and B cells and dendritic cells
Regulation of inflammatory cell trafficking into and out of the vessel
Adventitial – medial loop signals to control lumen caliber by short-term regulation of smooth muscle contraction and long-term regulation of remodeling
Contains resident vascular progenitor cells and may possess stem/progenitor cell niche-like activity

4. Porcine renal artery demonstrating tunica adventitia

5. Barotrauma → Restenosis: a Summary
Fibrosis
Adventitia
Inflammation
Recruitment
Proliferation
EEL
Basement membrane fracture
Phenotypic switch: quiescent → proliferative
Media
Recoil
Migration
Inflammation
Recruitment
Proliferation
Fibrosis
IEL
Stretching
Denudation
Thrombus
Recruitment
Neointima
INJURY
Fibrosis
Lumen
Lumen loss

6. Therapeutic Targets SIROLIMUS DEXAMETHASONE Fibrosis Adventitia
Inflammation
Recruitment
Proliferation
EEL
PRT-201
Basement membrane fracture
Phenotypic switch: quiescent → proliferative
Media
Recoil
Migration
Inflammation
Recruitment
Proliferation
Fibrosis
IEL
Stretching
Denudation
Thrombus
Recruitment
Neointima
INJURY
Fibrosis
Lumen
Lumen loss

8. Adventitial Drug delivery
Injection 9cm: 1.0 ml
After 3 minutes, diffusion up, down, and around >15cm of SFA
Injection 13.5cm: 1.0 ml
Injection 17cm: 1.0 ml
Success = longitudinal
+ circumferential distribution
Injection 21cm: 0.5 ml (not in frame)

9. Technical Success Markers
D003
D004
D016
D014
D019

10. Recombinant Human Type I Pancreatic Elastase (PRT-201)
26 kd serine protease
Degrades elastin fibers
Does not degrade collagen fibers
Localized effect
Inactivated in blood by antiproteases
Surgical (topical) and endovascular applications 10

11. PRT-201 Treatment Results in Fragmentation of Elastin Fibers Ex Vivo
Pre-Treatment
Post-Treatment
Treatment has no effect on collagen fibers, which provide resistance against rupture 11

12. Elastin Fragmentation Results in Artery Dilation In Vivo
Dilation Occurs Immediately
Dilation Persists
Before
After
Rabbit carotid artery treated with 8.3 mg/mL PRT-201 (n = 4 for each time point). Error bars represent standard deviation. 12

13. Initial Clinical Study
PRT-201 injection to femoral or popliteal artery by Mercator catheter following PTA
Open-label, dose-escalation
Cohorts of 4
PRT-201 at 1, 3, 10, 30 mg
Safety, technical feasibility
Lumen diameter and stenosis by duplex Doppler US
Entry criteria
Intermittent claudication
Stenosis of ≥ 70% of the SFA or popliteal artery
Target lesion length of ≤ 10 cm
At least one patent runoff vessel
N=7 so far 13

14. Anti-inflammation Program The Post-PTA Inflammatory Cascade
Balloon injury or vessel trauma
Hours
Days
Weeks
Months
Endothelial damage
DEX
Targets
 CRP, MCP-1, TNFa
 Endothelial healing
Further inflammation
is prevented
Vascular inflammation
Cytokine expression
(CRP, MCP-1, TNFa, IL-10, etc)
Cellular recruitment
(neutrophils, macrophages, etc.)
Cellular proliferation
(adventitial fibroblasts, smooth muscle cells, etc.)
Cellular migration & fibrous protein synthesis
(neointima, restenosis, occlusion)

15. + = ? Clinical Hypothesis
Adventitial delivery of dexamethasone at the time of peripheral artery endovascular revascularization will reduce inflammation and improve long-term patency* + = ?
*NOTE: Dexamethasone is not currently indicated for reducing vascular inflammation or improving vascular patency
FDA 510(k)-Cleared and CE Marked for infusion of agents into the vessel wall and perivascular area

16. DANCE Pilot
Design
20 patients enrolled between February 2011 and September 2012 at San Francisco VA Medical Center
DESIGN: Open-label, non-randomized, single-arm, single-center clinical feasibility evaluation of adventitial DEX after PAD intervention
OBJECTIVE: To evaluate technical success, safety and effectiveness outcomes of adventitial DEX delivered by Bullfrog® Catheter
PRINCIPAL INVESTIGATOR Christopher D. Owens, MD University of California San Francisco
Baseline blood draw for hsCRP levels
Revascularization Procedure
Adventitial DEX Treatment
24-hour blood draw for  hsCRP
Clinical, Hemodynamic and Duplex U/S follow-up at 6 months
Clinical, Hemodynamic and Duplex U/S follow-up at 12 months

17. DANCE Pilot Objectives
Technical success: Fluoroscopic blush of dex/contrast delivery into adventitia of SFA and popliteal artery with Bullfrog® Catheter. Dex/contrast delivered to the adventitia
Safety: vascular injury, thrombosis, embolization, dissection, death, and amputation
Effectiveness:
C-reactive protein rise from baseline to 24 hours
Assessments at 1, 3, 6, 9, 12 mo:
Lack of binary restenosis (Duplex U/S PSVR<2.5)
ABI improvement relative to baseline
Rutherford improvement relative to baseline

18. DANCE Pilot Demographics (N=20)
Age (mean ± SD)
66 ± 10
Gender (male,%)
20 (100%)
Race (caucasian, %)
10 (50%)
*Diabetes (positive, %)
11 (55%)
Hypertension (positive, %)
19 (95%)
Hyperlipidemia (positive, %)
Preoperative Rutherford classification
9=Rutherford =Rutherford 4
7=Rutherford =Rutherford 5
TASC II classification
A=3
B=9
C=7
D=1
*Occlusions (%)
Mean % occlusion (mean ± SD)
88 ± 12
*Mean lesion length cm (mean ± SD)
8.9 ± 5.3
Revascularization method
PTA in 20 patients (100%)
+ atherectomy in 3 patients (20%)
+ provisional stent in 6 patient (30%)

19. DANCE Pilot Treated Segment
Proximal SFA: 10%
Mid SFA: 14%
Note: 1 patient had treated segments in all three areas
Distal SFA: 38%
Popliteal: 48%

20. Safety and Feasibility (Technical) Endpoints
Safety: no adverse events. No dissection, hemorrhage, thrombosis, or pseudoaneurysm
Feasibility: Drug was delivered to the target vessel in 100% of cases.

21. DANCE Pilot Results Hemodynamic and Clinical Improvement, P<.0121

22. DANCE Pilot Efficacy Endpoint Adventitial DEX Inhibits Inflammatory Biomarker of Restenosis
Rise in C-reactive protein (CRP) predicts 6-month restenosis
No statistical rise from baseline to 24-hours in DANCE trial C-Reactive Protein levels
Schillinger , Radiology 2002

23. 6-month Patency Rates after Drug-Enhanced Fem-Pop Angioplasty23

24. Conclusions
Adventitial may have theoretical advantages for local drug deliver over intimal-based methodologies
Need to exploit more than proliferative pathways in lower extremity occlusive disease
Chemical stenting promising but need to establish dose and safety parameters
Dexamethasone infusion is safe, feasible, and demonstrates efficacy through reduced inflammation. A larger registry is set to begin and will be sponsored by Mercator MedSystems
MIC has a favorable profile in the SFA and popliteal arteries. Drug titration, scalable delivery, and visual confirmation of treatment offers theoretical advantages over DCB

25. Acknowledgements
Kirk Seward, Warren Gasper, Hugh Alley, Michael Conte, Karen Chong, Diana Kim
Funding: NIH NHLBI HL-92163, & R43HL102998, American Vascular Association, and the Department of Surgery University of California San Francisco, Proteon Therapeutics
Bullfrog Micro-Infusion Catheters were a gift from Mercator MedSystems, Inc. (San Leandro, Calif.)