Bioengineered AV Grafts: They Are Finally Happening! Jeffrey H. Lawson, M.D., Ph.D. Departments of Surgery and Pathology Duke University Medical Center Durham, North Carolina Lawson JH, FINANCIAL DISCLOSURE: Disclosure Information Consultant and Research Funding; Humacyte, Inc. None of the data presented in this lecture is intended to be perceived as claims for the potential clinical use of the bioengineered vascular graft discussed today. Vascular Grafts and Failure 40% of CABG vein grafts are occluded at 1 year. 1 Primary patency of lower leg vein bypass is 70% at 5 years in the best hands. 2 Significant wound issues related to vein harvest sites (nearly 15%). 3 Synthetic Vascular Dialysis Grafts Poor long-term patency Neointimal hyperplasia Stenosis Thrombosis Graft infections Graft wall deterioration/abuse DAC study indicated loss of patency in 75% of AVGs at one year 1 1. Prevent IV. JAMA, 294(19):2446-55, 2005 2. Rutherford, 5 th Edition, Chapter 69, pp. 1012-13, 2000 3. Duke Vascular Surgery NSQIP Data, 2013 1 Dixon et al. N Engl J Med 2009;360:2191-201. Page 1
Histology of Implanted eptfe Grafts Concepts and Beliefs Blood likes to move through tubes lined by cells Blood likes to move through tubes that wiggle Even the best veins don t like being arteries Bioengineered Blood Vessels Bioengineered blood vessels represent a potentially unlimited source of bypass grafts Bioengineered Blood Vessels: Created from Human Vascular Smooth Muscle Cells 1. Human Cells Isolated and Banked 2. Cells are Used to Culture s in Bioreactors However, in vivo implantation studies have been marked by acute graft rupture, thrombosis and failure 4. Without Branches 3. Decellularization Removes Cells Niklason, L et. al. Science 284:489-93, 1999. Page 2
Bioengineered Blood Vessels: Mechanically Similar to Native Vasculature Bioengineered Blood Vessels: Matrix of Acellular Vascular Grafts Silicone tube through side arm 6mm diameter, 40cm length Bioreactor PGA mesh scaffold Dacron sleeve Suture Strength (g) Burst Pressure (mmhg) HAVG 181 ± 18 (16) 3337 ± 343 (10) Human saphenous vein 196 ± 29 (7) 1599 ± 877 (7) Human internal mammary artery 138 ± 50 (6) 3196 ± 1264 (16) SEM shows fluid tight surface, with porous interior for cell infiltration. Kink Radius No weeping at physiologic pressures (N=31) Bioengineered Blood Vessels: Human Prototype Implanted into Primates (Baboon) Bioengineered Blood Vessels for AV Access: Baboon with Graft Cannulation Axillary Artery (Armpit): 3-4mm Diameter Bioengineered Vessel Brachial Vein (Elbow): 2-3mm Diameter Artery Outflow Vein Arteriovenous model, 1-6 months Accessible at 4 weeks, 16G needle Overall patency of 80% (11/14 animals), including 5 animals patent at 6 months No immunosuppression No increase in PRA No delayed hypersensitivity No graft calcification Page 3
Observations in Preclinical Studies (Baboon Model): Post-Implant Gross Observations of Bioengineered Blood Vessels PTFE Graft Investigational Investigational s Repopulate with Host Vascular Cells and Remodel: Baboon No Cells Pre-Implant Pre-implant Smooth muscle Alpha Actin CD 31 (endothelial) 6 Months Baboon Model Post-implant In preclinical studies, investigational bioengineered vessels: repopulate with vascular cells 1 1 Dahl et al., Sci Transl Med, 2011, 68ra9. Investigational s Repopulate with Host Vascular Cells and Remodel the Matrix Collagen Type I Immunostain Movat s stain - Elastin Little Intimal Hyperplasia in Investigational s in Preclinical Studies Venous anastomosis in a baboon eptfe Intimal to Medial Ratio (3 months) Pre-Implant 100µm 6 Months 6 Months Suture Strength (g) Burst Pressure (mmhg), Pre-Implant 180 ± 44 (N=12) 3415 ± 1011 (N=4), Post explant 276 ± 84 (N=11) 3669 ± 1305 (N=5) P-Value (Pre- vs Post-Implant) 0.01 0.13 Little foreign body reaction 1 Less mtor activated smooth muscle proliferation than autologous vein 2 1 Prichard et al., J Cardiovasc Translational Med, 2011, 674. 2 Quint et al., Proc Natl Acad Sci, 2011, 9214. Page 4
First Experience in Man Surgical Teams Study Design Open label, single arm study, 3 sites in Poland, initiated in Dec. 2012 Upper arm arteriovenous (AV) access for hemodialysis End stage renal disease (ESRD) patients who are not candidates for fistula creation Use for dialysis from 8 weeks Monthly clinical and ultrasound monitoring for first 6 months Patients followed for up to 2 years 28/30 patients enrolled Objectives Evaluation of safety and tolerability in dialysis patients Evaluation of patency and intervention rates Assess changes in Panel Reactive Antibody (PRA) 6 Month primary endpoint University of Medicine in Lublin Uniwersytet Medyczny w Lublinie Prof. Tomasz Zubilewicz Dr. Stanislaw Przywara Dr. Marek Ilzecki Medical University of Warsaw Akademia Medyczna Warszawie Prof. Jacek Szmidt Dr. Thomasz Jakimowicz Dr. Bodhan Solonynko Regional Specialist Hospital in Wroclaw Wojewódzki Szpital Specjalistyczny we Wrocławiu Prof. Wojciech Witkiewicz Dr. Jakub Turek Dr. Norbert Zapotoczny Study Patient Population and First Human Implant Initial Data on Investigational s 28 Caucasians [17 Male, 11 Female] Mean Age: 60 years (Range: 30 73) Mean BMI 28 (Range: 16 38) Concomitant diseases Hypertension in 82% Diabetes in 46% Vascular disease in 39% 4.1 ± 1.7 prior access procedures/patient Pa ents 88 66 44 22 00 0 1 2 3 4 5 6 7 8 Prior Dialysis Access Procedures First Human Implant of an Investigational Survival Distribution Function 1 0.8 0.6 0.4 0.2 100% Overall Patency All 28 vessels patent 20/28 without intervention No infections, no aneurysm Secondary patency 100% Primary patency (9 patients at 6 month follow up) Venous Anastomosis Arterial Anastomosis Vessel in Upper Arm 0 0 1 2 3 4 5 6 Months Page 5
Initial Data on Investigational s No indication of immune response % Reac vity to PRA Class I An bodies 10 # 8 # 6 # 4 # 2 # 0 # No change in PRA Class I Reac vity [N=6] Pre-Implant 3 Months Post-Implant 0% reac vity to PRA Class 2 in pre- & post-implant measurements [N=6] Flow rate (ml/min) Diameter (mm) 8 " 6 " 4 " 4000 " 3000 " 2000 " 1000 " No dilata on or aneurysms [N=25] 0" 50" 100" 150" 200" 250" 300" 0 50 Days on Study Flow rates suitable for dialysis [N=25] 0 " 0 50 100 150 200 250 300 Days on Study Investigational for Dialysis Bioengineered Vessel Flow rates suitable for dialysis: >500ml/min Being Used for Dialysis 22 patients using bioengineered vessels for dialysis 3 times per week >800 accesses, up to 9 months experience per graft Grafts easy to cannulate using standard techniques Only one delayed hemostasis requiring intervention Patient had low fibrinogen levels (0.2g/L; Normal range: 2-4g/L) Summary Thank You Off-the-shelf bioengineered vascular grafts are possible Non immunogenic Integrate with native tissue, repopulate and remodel Post implant with increased strength and little intimal hyperplasia First-in-man pilot clinical trial underway in Poland and the US for hemodialysis access and PAD Page 6
Initial Data on Investigational s Duke Hospital: June 5, 2013 Pa ents CURRENT OVERALL PATENCY 100% Thrombosis Stenosis 8 of 28 patients lost primary patency since December 2012 10 patency interventions in these 8 patients 8 thrombectomies (1 with revision of anastomosis, 1 with angioplasty) 2 venous anastomosis angioplasties without thrombosis 71% Primary unassisted patency 0 1 2 3 4 5 6 7 8 9 10 11 Dura on of Implanta on (Months) 1 steal syndrome: cuff placed Page 7