Novel Treatment for the Problem Diabetic Wound

Novel Treatment for the Problem Diabetic Wound William J. Lindblad, Ph.D. Professor of Pharmacology Chair, Dept. of Basic Pharmaceutical Sciences Director, Office of Research & Scholarship

Objectives Review the causes, prevalence and complications of diabetes mellitus. Consider the impact of diabetes on the wound healing process. Present current therapeutic options for the diabetic wound. Discuss novel approaches to treating diabetic wounds.

Disclosures Dr. Lindblad has limited patent rights to human keratinocyte-based wound therapeutics & could obtain royalty payments for the Keracure wound care device.

Prevalence and Complications of Diabetes Mellitus

Type I vs. Type II Diabetes Type I diabetes (juvenile, IDDM) is initially diagnosed in the pediatric population and w/ a different etiology than type II diabetes (adult, NIDDM). However, diabetic foot ulcers can occur in both type I and II diabetics. Due to the much larger fraction of diabetics that are type II diabetics, and because the prevalence of this form is increasing, will focus on the latter group. It is also possible that there are mechanistic differences that will not be discussed in this talk.

Risk Factors for Type II Diabetes Weight obesity is a primary risk factor Fat distribution visceral vs. peripheral (subcutaneous) Inactivity Family history Race/Ethnic groups high risk groups African & Asian- American, American Indian, Hispanic Age over 45 Pre-diabetes Gestational diabetes

Adult Diabetes Prevalence in U.S.A. (2010)

Obesity Trends* Among U.S. Adults BRFSS, 1990, 2000, 2010 (*BMI 30, or about 30 lbs. overweight for 5 4 person) 1990 2000 2010 No Data <10% 10% 14% 15% 19% 20% 24% 25% 29% 30% Source: CDC vital signs composite: Behavioral risk factor surveillance system

Adult Diabetes Prevalence in Maine (2010) Source: Maine CDC

Impact of Diabetes on Wound Healing

Initial Wound Hemostasis

Acute Inflammation

Re-epithelialization & Matrix Deposition

Remodeling

Concurrent Wound Events

Diabetic Alterations Macro changes: Neuropathy Peripheral arterial disease Enhanced bacterial load (biofilms) Micro changes: Thickening of the vascular basement membrane Abnormal vascular proliferation Altered extracellular matrix characteristics Damage/killing of various cell types

Protein Glycosylation Many proteins can have glucose moieties chemically linked to them (glycosylation) if tissue levels of glucose are chronically high, e.g HbA1c. The glucose on the glycosylated proteins are then chemically changed into a more stable chemical product called advanced glycation endproducts (AGE). The AGEs can then engage specific receptors or RAGEs on endothelial cells, fibroblasts, macrophages and others to influence the inflammatory response.

AGE & Inflammation The interaction of AGEs w/ RAGE on cells initially inhibits the inflammatory response. However, this will set up conditions for the acute inflammatory response that is needed for healing to convert into a chronic inflammatory state. This state includes elevated levels of proteases and reactive oxygen species that can damage cells and prevent the reformation of the damaged connective tissue matrix.

AGE, RAGE & EN-RAGE

Influence of Glucose Levels (HbA1c) on Healing J. Invest. Dermatol. 2011; 131(10):2121-2127.

HbA1c vs. Healing Rate J. Invest. Dermatol. 2011; 131(10):2121-2127.

Current Therapeutic Options

Diabetic Wound Treatment - Prevention Prevention as with most clinical problems prevention is key to reducing the problem of diabetic ulcers. Maintain good glucose control Maintain good skin hydration and prevent breakdown of the epidermis w/ the use of emollients Regular foot inspections Protection of the foot particularly when diabetic nephropathy has developed

Standard Care for Diabetic Wounds Standard wound care includes elements of good wound care in general: Use moist wound healing principles Debride the wound if excessive dead/necrotic tissue present Use topical antibiotics to control infection but do not use if no signs of infection Protect the foot and use pressure-relieving orthotics

Current Treatment Status Current treatment of diabetic foot ulcers has been improving. UPenn study (2005) showed that between 1991 and 2000, the percent of neuropathic foot ulcers that healed increased from 38% to 68%. Primary reason for improvement were patients being seen earlier in the development of the foot ulcers. Still a significant number of ulcers not responding to standard treatments.

If Standard Wound Care is Not Enough Many options available to treat the diabetic foot ulcer that will not close despite optimal wound care, including: Apligraf Hyperbaric oxygen Negative pressure Growth factors - Becaplermin Honey/Sugar

Cost Studies Many of the novel treatment approaches are expensive. Studies have shown that incorporation of these novel approaches in appropriate patients can be costeffective. One study compared Apligraf, Dermagraft, and Regranex and found favorable cost-effectiveness ratios. (Langer A, Rogowski W. BMC Health Svc Res 2009;9:115) These results are because of shorter treatment periods, fewer complications and fewer in-patient stays.

Novel Approach

Keratinocyte Sheets Human keratinocyte first grown as dermal burn wound coverage. Subsequently, have been used to cover dermal ulcers of different etiology w/ variable results. Idea was to increase the cell density within ulcers by growing cells on microcarrier beads. Allogeneic human keratinocytes (FDA certified cell bank) seeded on microcarrier beads and allowed to grow for 1-2 weeks.

Keratinocyte-populated microcarrier beads (KPMB) Designed as devices for treatment of problem wounds Consist of Cytoline microcarrier beads with primary human keratinocytes grown on the beads Cell biology of keratinocytes can be studied on the microcarrier beads, as well as their clinical application

KPMB day 12 keratinocyte

32 Viable Keratinocytes on Cytoline-1 Beads

KeraPac (KC-002) Cytoline-1 Microcarrier Beads (GE Healthcare) Delnet Bag (Delstar Technologies) Keratinocytes (Neonatal Foreskin Tissue) 33

Potential MOA for KPMB in problem wounds The cells may modify the wound fluid be: Secreting growth factors PDGF, VEGF Secreting anti-proteases SLPI (secretory leukocyte protease inhibitor) a serine proteinase inhibitor Altering fluid ph, oxidant levels H 2 O 2 Other possibilities

PDGF (pg/ml PDGF Secretion 25 20 15 10 Keratino cytes 5 0 C o ntro l 9 Values indicate PDGF accumulated in medium over 24 hr. time period.

VEGF (pg/ml) VEGF Secretion 120 100 80 60 40 Keratino cytes 20 0 C o ntro l 9

Multicenter Clinical Trial 186 patients (~81% of required 230) enrolled to date 24 leading institutions participating in trial Harvard Medical School Johns Hopkins Georgetown Boston University Scott & White Confidential Use Only May 23, 2008 Revision 37

Effectiveness Endpoints Primary Endpoint Percent of Patients Achieving Complete Study Wound Closure (100%) by Week 12 (84 days) of Treatment Secondary Endpoints Recurrence, Infection, Osteomyelitis, Amputation, Time to Reach Closure 38

Internal Analysis of 94 Patients Primary endpoint: % of patients with complete wound closure by week 12 44.4% 45 40 35 30 25 20 15 10 5 0 22.4% Control KeraPac (11/49 patients) (20/45 patients) KeraPac Performance 22% absolute advantage (p=0.0312) Twice the number of patients healed within 12 weeks No recurrence of healed wounds within 6 months Internal Analysis performed by Averion International on initial ITT 94 patients 39

Multicenter Trial Patient 014/M-G/110 Screening Visit Week 3 Week 6 Week 12 40

C umulative % of P atiens with C omplete Wound C los ure Cumulative Percent of Patients Healed Per Week of Treatment 50% C umulative P erc entag e of Diabetic F oot Ulc er P atients Healed P er Week of T reatment with K erap ac Data from 94 Intent-to-T reat P atients (45 K erap ac, 49 C ontrols ) K erap ac C ontrol 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% 1 2 3 4 5 6 7 8 9 10 11 12 Weeks of T reatment 41

Percentage Points Above Controls Percent of Treated Patients with Complete Wound Closure at 12 weeks vs. Control 25 Diabetic Foot Ulcer Indication, 12 Weeks Post-Initial Treatment 22 20 17 15 12 10 10 5 0 Regranex Dermagraft Apligraf KeraPac Source: Regranex website Source: Diabetes Care, June 2003 Source: Apligraf website N = 94 patients) 42

% of Patients Healed by 12 Weeks Healing Rates vs. Reported Wound Duration Prior to Treatment Initiation DFU Healing as Function of Wound Duration KeraPac Treatment vs Standard of Care (CTL) 100 90 KC-002 CTL 80 70 60 50 40 30 20 10 0 1-6 7-9 10 + Reported Wound Duration (Months) For wounds of < 6 months duration, 75% treated with KeraPac vs. 45% treated with control heal within 12 weeks 43

Competitive Data Comparison: Secondary Endpoints Multicenter Pivotal Study Results vs. Published KeraPac N=94 Apligraf N=208 Dermagraft N=314 Treatment Control Treatment Control Treatment Control Time to Healing 45 days 56 days 65 days 90 days +70 days NA Recurrence 0.0% 2.1% 8.0% 17.0% 26.0% 22.0% Osteomyelitis 2.2% 2.1% 2.7% 10.4% 8.6% 8.6% Infection 6.7% 8.1% 10.7% 13.5% 10.4% 17.9% Cellulitis 4.4% 4.1% 8.9% 8.3% 7.4% 9.3% Surgery 2.2% 4.1% 6.25% 15.6% 8.0% 13.2% 44

Summary Diabetes is increasing within the U.S. population and can directly alter the wound environment. Prevention approaches are best to minimize the development of diabetic ulcers. Standard of care approaches are able to facilitate healing for the majority of ulcers, w/ those treated early providing the best results. Novel approaches may need to be taken in those patients w/ recalcitrant ulcers that fail to heal.