Compliance with the provisions in this LCD may be monitored and addressed
through post payment data analysis and subsequent medical review audits.

**History/Background and/or General Information**

This LCD addresses the medically reasonable and necessary threshold for
coverage of skin replacement surgery for application of skin substitute grafts
for diabetic foot ulcers (DFUs) and venous leg ulcers (VLUs).

Application of skin substitute grafts for wound care indications other than
for DFU or VLU are not addressed by this LCD. Use of skin substitute grafts
must meet the medically reasonable and necessary threshold for coverage and
these devices must be used in accordance with their approved United States
(U.S.) Food and Drug Administration (FDA) intended use.

Chronic wounds of the lower extremities, including venous stasis ulcers, DFUs
and pressure sores, are a major public health problem. While lower extremity
ulcers have numerous causes such as burns, trauma, mixed venous-arterial
disease, immobility, and vasculitis, nutritional or other neuropathy, over 90%
of the lesions in the U.S. are related to venous stasis disease and diabetic
neuropathy.1-3

Generally, depending on the purpose of the product and how it functions, skin
substitutes are regulated by the FDA premarket approval (PMA) process, FDA
510(k) premarket notification process, or the FDA regulations for human cells,
tissues, and cellular and tissue-based products (HCT/Ps). Although skin
substitutes have attributes of both biologicals and devices, the current
position is that these products are best characterized as surgical supplies or
devices because of their required surgical application and their similarity to
other surgical supplies. It has been noted that there are instances in which
certain products might have a wound healing indication but may not necessarily
meet the definition of skin substitutes. Therefore, FDA classification and
indication alone does not determine if a product meets the definition of skin
substitute and/or meets the medically reasonable and necessary threshold for
coverage.

Amniotic/chorionic-based products are HCT/Ps as defined in 21 CFR 1271.3(d)
and must meet criteria in 21 CFR 1271 and 361 of the Public Health Service Act
(PHS Act). The HCT/Ps not regulated under 361 are regulated as drugs as
defined under section 201(g) of the Federal Food, Drug, and Cosmetic Act (the
Act) [21 U.S.C. 321(g)] and biological products as defined in section 351(i)
of the PHS Act [42 U.S.C. 262(i)]. In order to lawfully market a drug that is
also a biological product, a valid biologics license must be in effect [42
U.S.C. 262(a)]. Such licenses are issued only after a showing of safety and
efficacy for the product's intended use.4-6

Standard treatment of lower extremity ulcers (e.g., DFUs and/or VLUs) may
include mechanical offloading, infection control, mechanical compression, limb
elevation, debridement of necrotic tissue, management of systemic disease and
medications, nutrition assessment, tissue perfusion and oxygenation, and
counseling on the risk of continued tobacco use. In addition, maintenance of a
moist wound environment through appropriate dressings facilitates development
of healthy granulation tissue and epithelialization and thus may potentiate
complete healing at a wound site. Dressings are an integral part of wound
management by not only maintaining a moist environment but by stopping
contamination and absorbing exudate.7-12

Despite advancements in various synthetic occlusive dressings some ulcers fail
to heal. The development of skin substitutes has been employed as an adjunct
to established wound care methods to increase the chances of healing.1,13

Chronic wounds and frequently recurring wounds related to DFUs and VLUs are a
challenge to treat effectively. Chronic wounds may be unresponsive to initial
therapy or persist despite additional care. A wound that has not healed within
one to three months may be considered chronic and the application of a skin
substitute graft, an advanced treatment modality, may be considered medically
reasonable and necessary for certain patients.1-3

Patients receiving skin replacement surgery with a skin substitute graft
should be under the care of a physician/non-physician practitioner (NPP) for
the treatment of their systemic disease process (e.g., diabetes mellitus,
chronic venous insufficiency, and/or peripheral vascular disease). It is
imperative that their systemic disease be monitored/treated in order to ensure
adequate healing of the wound site.3,9

It is the expectation that a specific skin substitute graft product will be
used for the episode of skin replacement surgery for wound care (defined as 12
weeks from the first application of a skin substitute graft) assuming its use
is not in conflict with the FDA assessments (e.g., indications,
contraindications, how supplied and directions for use, etc.) and/or the
American Association of Tissue Banks (AATB) approved use and assuming there is
one related wound. Repeat application of a skin substitute graft within the
12-week episode of skin replacement surgery for wound care may be appropriate
per the package insert based on wound re-assessment and must be supported in
the medical record documentation for that encounter. Additional applications
of a skin substitute product beyond the 12- week episode of skin replacement
wound care are not expected if the wound has responded to the skin replacement
surgery with epithelialization and other progression. This LCD does not
endorse particular products for separate payment. The medical record
documentation must support the medical necessity for skin replacement surgery
and that the product is being used within its approved FDA indications.

**Covered Indications**

If the patient meets all of the criteria as outlined in this LCD, application
of a skin substitute graft for lower extremity DFU or VLU is considered
medically reasonable and necessary for the following:

  1. The presence of a chronic, non-infected DFU having failed to respond to documented conservative wound care measures (outlined below) for greater than four weeks with documented compliance.7
  2. The presence of a chronic, non-infected VLU having failed to respond to documented conservative wound care measures (outlined below) for greater than four weeks with documented compliance.10

  * For purposes of this LCD, conservative wound care measures include, but are not limited to2,7-12:

Comprehensive patient assessment (history, exam, Ankle-Brachial Index [ABI])
and diagnostic tests as indicated) and implemented treatment plan.

For patients with a DFU - assessment of Type 1 vs. Type 2 diabetes and
management history with attention to certain comorbidities (e.g., vascular
disease, neuropathy, osteomyelitis), review of current blood glucose
levels/hemoglobin A1c (HbA1c), diet and nutritional status, activity level,
physical exam that includes assessment of skin and wound, ABI, and check of
off-loading device or assessment of appropriate footwear.3

For patients with a VLU - assessment of clinical history (prior ulcers,
thrombosis risks), physical exam (edema, skin changes), ABI, diagnostic
testing to verify superficial or deep venous reflux, perforator incompetence,
and chronic (or acute) venous thrombosis. In this regard, venous duplex
ultrasound is recommended to confirm the Clinical class, Etiology, Anatomy,
and Pathophysiology (CEAP) classification and categorize the patient's chronic
venous disorder to guide the analysis of management alternatives. The Venous
Clinical Severity Score (VCSS) is used to assess changes in response to
therapy.

  3. An implemented treatment plan demonstrating all of the following:

  * Debridement as appropriate.
  * Some form of offloading for DFUs and some form of compression for VLUs.
  * Infection control.
  * Management of exudate - maintenance of a moist environment (moist saline gauze, other classic dressings, bioactive dressing, etc.).
  * Patient is a nonsmoker or has refrained from smoking for at least 6 weeks prior to planned skin replacement surgery or has received counseling on the effects of smoking on surgical outcomes and treatment for smoking cessation.

  4. The skin substitute graft is applied to an ulcer that has failed to respond to documented conservative wound care measures. "Failed response" is defined as an ulcer that has increased in size or depth, or no change in baseline size or depth, or no sign of improvement or indication that improvement is likely (such as granulation, epithelialization, or progress towards closing). Documentation of response requires measurements of the initial ulcer, measurements at the completion of at least four weeks of conservative wound care measures, and measurements immediately prior to placement of the skin substitute graft for a DFU. For VLUs, conservative wound care measures must continue for no less than four weeks and include on-going compression therapy.7,10,13

  5. The medical record documentation specifically addresses the circumstances regarding why the wound has failed to respond to standard wound care treatment of greater than 4 weeks and references the specific interventions that have failed based on the prior wound evaluation. The record must include an updated medication history, review of pertinent medical problems that may have arisen since the previous wound evaluation, and explanation of the planned skin replacement surgery with choice of skin substitute graft product. The procedure risks and complications must also be reviewed and documented.7,10,13-14
  6. Skin substitute grafts utilized per the approved FDA intended use.
  7. The patient is under the care of a qualified physician/NPP for their underlying chronic condition.3,9

**Limitations**

The following are considered not medically reasonable and necessary1-3,9-10:

  1. Not to exceed four applications of a specific skin substitute graft product within the episode of skin replacement surgery for wound care defined as 12 weeks from the first application and consistent with product labeling. 
    * The expectation is treatment will consist of the fewest repeat applications and amount of product to heal the wound. It is expected that products are used per the labeling. It is not expected that every ulcer, in every patient will require the maximum number of applications listed on the product label. This utilization pattern may be subject to focused medical review.

  2. Switching skin substitute graft products in a 12-week episode of skin replacement surgery for wound care. Exceptions should be rare and may be considered on appeal when the medical necessity of the change is clearly documented in the medical record.
  3. Application of a skin substitute graft product beyond 12-weeks.
  4. Repeat applications of skin substitute grafts when a previous application was unsuccessful. Unsuccessful treatment is defined as increase in size or depth of an ulcer, or no change in baseline size or depth and no sign of improvement or indication that improvement is likely (such as granulation, epithelialization, or progress towards closing).
  5. Application of skin substitute grafts in patients with inadequate control of underlying conditions or exacerbating factors, or other contraindications (e.g., uncontrolled diabetes, active infection, active Charcot arthropathy of the ulcer extremity, active vasculitis).
  6. Use of surgical preparation services (for example, debridement), in conjunction with routine, simple and/or repeat skin replacement surgery with a skin substitute graft.
  7. Excessive wastage (discarded amount).

  *     * The skin substitute graft must be used in an efficient manner utilizing the smallest package size available for purchase from the manufacturer that could provide the appropriate amount for the patient.

  8. All liquid skin substitute products for wound care.15
  9. Refer to the CFR, Title 21, Volume 8, Chapter 1, Subchapter L, Part 1271.10 for Human-derived products   
regulated as human cells, tissues, or cellular or tissue-based product (HCT/P)
for additional limitations.

**Provider Qualifications**

Services provided within the LCD coverage indications will be considered
medically reasonable and necessary when all aspects of care are within the
scope of practice of the provider's professional licensure; and when all
procedures are performed by appropriately trained providers in the appropriate
setting.

**Notice:** Services performed for any given diagnosis must meet all the
indications and limitations stated in this LCD, the general requirements for
medical necessity as stated in CMS payment policy manuals, any and all
existing CMS national coverage determinations, and all Medicare payment rules.



A literature search was conducted using the following key words: Non-healing;
wound; chronic; diabetic foot; foot ulcer; venous leg ulcer; guidelines; wound
healing; skin substitutes; dermal skin substitute; human skin allograft;
randomized trial; standard of care; venous leg ulcer; skin grafts; wound
dressing; human derived products; animal derived products; FDA regulations.
The literature search was filtered to locate articles within 5-10 years, full-
text articles, clinical trials, and systematic reviews. In general, improved
health outcomes of interest include patient quality of life and function.

**Introduction**

Chronic wounds are described as wounds which have been unable to re-
epithelialize after 1 to 3 months of treatment. More than 90% of chronic
wounds in the United States (U.S.) are a result of diabetic ulcers, venous
stasis ulcers, and decubitus ulcers. Chronic wounds may be described as
vascular ulcers (e.g., venous and arterial), diabetic ulcers, and pressure
ulcers (local tissue hypoxia). These types of chronic wounds impact patient
quality of life due to impaired mobility, pain, and substantial morbidity.1-3

**Evidence-Based Guidelines for Standard of Care**

Evidence-based guidelines indicate that standard of care (SOC) treatment of
lower extremity ulcers (e.g., diabetic foot ulcers [DFUs] and/or venous leg
ulcers [VLUs]) may include mechanical offloading, infection control,
mechanical compression, limb elevation, debridement of necrotic tissue,
management of systemic disease and medications, nutrition assessment, tissue
perfusion and oxygenation, education regarding care of the foot, callus, and
nail and fitting of shoes, and counseling on the risk of continued tobacco
use. In addition, maintenance of a moist wound environment through appropriate
dressings facilitates development of healthy granulation tissue and
epithelialization and thus may potentiate complete healing at a wound site.
Dressings are an integral part of wound management by not only maintaining a
moist environment but by stopping contamination and absorbing exudate.7-12

A comprehensive assessment of patients and their wounds will also facilitate
appropriate care by identifying and correcting systemic causes of impaired
healing. The presence of a severe illness or systemic disease and drug
treatments such as immunosuppressive drugs and systemic steroids may inhibit
wound healing by changes in immune functioning, metabolism, inflammation,
nutrition, and tissue perfusion. Therefore, this information in conjunction
with a detailed history of the wound itself is essential.3,9

A vascular evaluation is also vital for all chronic wounds. Palpation of
pulses may be problematic in cases of medial arterial calcification. An ankle-
brachial index (ABI) should be taken for patients with a questionable pulse
deficit although the ABI levels may be falsely elevated with medial arterial
calcification. The patient is considered to have impaired arterial perfusion
when the ABI is below 0.9. To supplement ankle-brachial studies, toe blood
pressure readings, pulse volume recordings, transcutaneous oxygen measurements
(TCOMs), and skin perfusion pressure measurements have been suggested as
acceptable benchmarks for the prediction of wound healing.3

Venous ulcers require a series of diagnostic testing to verify superficial or
deep venous reflux, perforator incompetence, and chronic (or acute) venous
thrombosis. In this regard, venous duplex ultrasound is recommended and if the
venous duplex ultrasound does not provide definitive diagnostic information, a
venous plethysmography is recommended. Patients with mixed arterial and venous
disease require a combination of arterial and venous noninvasive testing. The
use of a Class 3 (most supportive) high-compression method is strongly
recommended in the treatment of venous ulcers. High strength compression may
be applied using techniques such as multilayered elastic compression,
inelastic compression, Unna boot, compression stockings, and others. The
extent of compression should be modified for patients with mixed
venous/arterial disease.3,10

The clinical practice guidelines of the Society for Vascular Surgery and the
American Venous Forum10 recommend that patients with VLUs have the ulcer
classified using the Clinical class, Etiology, Anatomy, and Pathophysiology
(CEAP) classification (confirmed by duplex scan). The Venous Clinical Severity
Score (VCSS) is recommended to assess changes in response to therapy. Specific
classification of venous disease is essential for standardization of venous
disease severity and evaluation of treatment efficiency.

The Society for Vascular Surgery in collaboration with the American Podiatric
Medical Association and the Society for Vascular Medicine has recommended a
SOC treatment schedule for DFUs that includes weekly to monthly wound
evaluations of wound size and healing progress, infection control, debridement
of all devitalized tissue and surrounding callus material, dressings that
maintain a moist wound environment, control of exudate, and avoiding
maceration of adjacent intact skin. Adequate glycemic control of hemoglobin
A1c (HbA1c < 7%) is also recommended to reduce the incidence of DFUs and
infections and periodic assessments of appropriate footwear and/or off-loading
device.7,13

**Regulation of Skin Substitute**

Despite standard of care and advancements in various moisture retaining
synthetic occlusive dressings, many chronic wounds fail to heal. The
development of skin substitutes has been employed to be used as an adjunct to
established chronic wound care methods to increase the chances of healing.1,13
Skin substitute can be organized into the following groups: 1) Human-derived
products regulated as human cells, tissues, and cellular and tissue-based
products (HCT/Ps); 2) Human and human/animal-derived products regulated
through premarket approval (PMA) by the U.S. Food and Drug Administration
(FDA); and 3) Animal-derived products regulated under the 510(k) process; and
4) Synthetic products regulated under the 510(k) process.4-6

Human tissue can be obtained from human donors, processed, and used in exactly
the same role in the recipient, such as a dermal replacement to be placed in a
wound as a skin substitute (regulated as HCT/Ps). These products may be
regulated under the Biologics License Application (BLA) (under the Public
Health Service Act [PHS Act]) or PMA (under the Federal Food, Drug, and
Cosmetic Act [FD&C Act]), depending on their composition and primary mode of
action. Amniotic/chorionic-based products are HCT/Ps as defined in 21 CFR
1271.3(d) and must meet criteria in 21 CFR 1271 and 361 of the PHS Act. The
HCT/Ps not regulated under 361 are regulated as drugs as defined under section
201(g) of the Federal Food, Drug, and Cosmetic Act (the Act) [21 U.S.C.
321(g)] and biological products as defined in section 351(i) of the PHS Act
[42 U.S.C. 262(i)]. In order to legally market a drug that is also a
biological product, a valid biologics license must be in effect [42 U.S.C.
262(a)]. Such licenses are issued only after a showing of safety and efficacy
for the product's intended use.6

**Evidence-Based Guidelines for Skin Substitute**

Skin substitute are a heterogeneous group of biological and/or synthetic
elements that allow the temporary or permanent occlusion of wounds. Dermal
substitutes may vary from skin xenografts or allografts to a combination of
autologous keratinocytes over the dermal matrix, but all have a mutual goal to
attain resemblance with an individual's skin to the greatest extent
possible.13 Skin substitute are recommended as an adjunct to the established
SOC treatment protocols for wound care to increase the chances of healing. In
this regard, evidence-based guidelines recommend wound bed preparation prior
to the application of any biologically active dressing which includes complete
removal of slough, debris and/or necrotic tissue.14 Skin substitutes are
recommended in conjunction with SOC treatment for DFUs that have failed to
demonstrate more than 50% wound area reduction after a minimum of four weeks
of standard wound care measures.7 For VLUs, if substantial wound improvement
is not demonstrated after a minimum of four-six weeks of standard wound care
measures, skin substitutes are recommended in addition to SOC treatment and
compression therapy.10

**Technology Assessment**

The Agency for Healthcare Research and Quality (AHRQ) provided an evidenced-
based technical brief for skin substitutes for treating chronic wounds.2 This
technical brief was developed to describe assorted products that may be
considered skin substitutes in the U.S., which are utilized for the treatment
of chronic wounds. In addition, systems utilized to classify skin substitutes
were assessed, randomized controlled trials (RCTs) involving skin substitutes
were reviewed, and recommendations were made regarding best practices for
future studies. A systematic search of the published literature since 2012 was
conducted for systematic reviews/meta-analyses, RCTs, and prospective
nonrandomized comparative studies studying commercially available skin
substitutes for individuals with DFUs, VLUs, pressure ulcers, and arterial leg
ulcers.

Seventy-six skin substitutes were identified and categorized using the
Davison-Kotler classification system, a method structured according to
cellularity, layering, replaced region, material used, and permanence. Of
these, 68 (89%) were categorized as acellular dermal substitutes, largely
replacements from human placental membranes and animal tissue sources.
Acellular dermal substitutes prepared from natural biological materials are
the most common commercially available skin substitute product for treating or
managing chronic wounds. Cellularity is a significant difference among skin
substitutes as the presence of cells raises the rejection risk and production
complexity. This category includes decellularized donated human dermis (14
products recognized), human placental membranes (28 products recognized), and
animal tissue (21 products recognized). Less products are prepared from
synthetic materials (two products recognized) or a blend of natural and
synthetic materials (two products recognized). A limited number of skin
substitute products are acellular replacements for both the epidermis and
dermis (one product recognized). Only eight products were recognized that
contain cells and would be classified in the cellular grouping.

Three systematic reviews and 22 RCTs studied the utilization of 16 distinct
skin substitutes, comprising acellular dermal substitutes, cellular dermal
substitutes, and cellular epidermal and dermal substitutes in DFUs, pressure
ulcers, and VLUs. Twenty-one ongoing studies (all RCTs) assessed an additional
nine skin substitutes with comparable classifications. It was noted that
studies seldom reported clinical outcomes, such as amputation, wound
recurrence at least two weeks after treatment ended, or patient-related
outcomes, such as return to function, pain, exudate, and odor. This review
found that more studies are needed to assess the effectiveness of most skin
substitutes and studies need to be better designed and include clinically
relevant outcomes.

Of the 22 included RCTs, 16 studies contrasted a skin substitute with SOC. The
SOC for each wound type involved sharp debridement, glucose control,
compression bandages for VLUs, pressure redistribution support surfaces for
pressure ulcers, infection control, offloading, and daily dressing changes
with a moisture-retentive dressing, such as an alginate or hydrocolloid type
dressing. Though 85% of the studies examining acellular dermal substitutes
portrayed the experimental intervention as favorable over SOC for wound
healing and quicker time to heal, inadequate data is available to determine
whether wound recurrence or other sequela are less frequent with acellular
dermal substitutes. Only three studies contrasted cellular dermal substitutes
with SOC. Clinical evidence for cellular dermal substitutes may be limited by
the lack of robust, well-controlled clinical trials.

Of the six head-to-head comparative studies, results from five studies did not
show substantial differences between skin substitutes in outcomes measured at
the latest follow-up (>12 weeks). One study concluding at 12 weeks described a
substantial difference in wound healing favoring an acellular dermal skin
substitute over a cellular epidermal and dermal skin substitute. Another study
compared two acellular dermal substitutes and seemed to have deliberately
underpowered one arm of the study as statistical significance was not sought
or expected for this study arm. Of the two studies reporting on recurrence,
one study described comparable recurrence, while the other study reported no
recurrence at 26 weeks. The current evidence base, as portrayed by the authors
for the literature reviewed, may be inadequate to determine whether one skin
substitute product is superior to another.2

Industry sponsored most of the studies reviewed; 20 of the 22 RCTs in this
review, which presents concerns regarding bias for these studies. This AHRQ
technical brief also noted that a skin substitute's commercial availability is
not a reflection of its legal status. Manufacturers self-determine whether
their human cells, tissues, or cellular or tissue-based product (HCT/P) may be
marketed without FDA preapproval and frequently misunderstand or
mischaracterize the conditions they must meet for the product to be regulated
solely for communicable disease risk.

The Code of Federal Regulations (CFR) was referenced; 21 CFR 1271.10(a). Also,
the 'FDA Announces Comprehensive Regenerative Medicine Policy Framework'5 was
referenced.

**Systemic Review and Meta-Analysis**

Santema et al16 provided a systematic review and meta-analysis to assess the
efficiency of skin substitutes utilized for the treatment of DFUs regarding
ulcer healing and limb salvage. Using the Cochrane Collaboration methodology,
17 clinical trials were identified, which included a total of 1,655 randomized
study participants with diabetic foot ulceration. The number of study
participants per clinical trial ranged from 23 to 314. Fourteen studies
included chronic or difficult to heal ulcers that were present for a minimum
of 2, 4, or 6 weeks.

Skin substitutes were contrasted with SOC in 13 trials. The results
collectively demonstrated that SOC treatment, together with skin substitutes,
enhance the chances of attaining complete ulcer closure in contrast to SOC
alone after 6 to 16 weeks (risk ratio [RR] 1.55, 95% confidence interval [CI]
1.30 to 1.85, low quality of evidence). Apligraf/Graftskin, Epifix, and
Hyalograft 3D were the only individual products that demonstrated a
statistically substantial beneficial effect on complete ulcer closure (i.e.,
full epithelialization without any evidence of drainage or bleeding). Four
clinical trials contrasted two different types of skin substitutes, although
no product demonstrated a greater effect over another. Sixteen of the trials
evaluated the efficacy of a bioengineered skin substitute. Only one trial
evaluated the efficacy of a nonbioengineered skin graft.

The total occurrence of lower limb amputations was only reported for two
trials and the results for these two trials collectively produced a
substantially lower amputation rate for individuals treated with skin
substitutes (RR 0.43, 95% CI 0.23 to 0.81), though the absolute risk
difference (RD) was small (-0.06, 95% CI -0.10 to -0.01, very low quality of
evidence). Of the included studies, 16 reported on adverse events (AEs) in
different ways, although there were no reports of a substantial difference in
the incidence of AEs between the intervention and the control group.
Additionally, support of long-term effectiveness is lacking, and cost-
effectiveness is unclear. Noted limitations included a variable risk of bias
among the studies, the lack of blinding (i.e., study participants and
investigators knew which patients were receiving the experimental therapy and
which patients were receiving the standard therapy), and 15 of the studies
conveyed industry involvement; the majority of which did not indicate if the
industry applied any limitations regarding data analysis or publication.16

Jones et al17 provided a fourth update for a systematic literature review to
evaluate the effect of skin grafts for the treatment of VLUs. Using the
Cochrane Collaboration methodology, one new trial was identified, generating a
total of 17 RCTs, which included a total of 1,034 study participants. The
studies comprised participants of any age, in any care setting, and with VLU.
Given the process for diagnosis of venous ulceration differed between studies,
a standard definition was not applied. The trials also involved study
participants with arterial, mixed, neuropathic, and diabetic ulcers provided
that the outcomes for patients with venous ulcers were conveyed separately. To
be included in the review, trials also had to report at least one of the
primary outcomes (i.e., objective measures of healing, such as relative or
absolute rate of change in ulcer area, time for complete healing, or
proportion of ulcers healed within the trial period).

Eleven studies contrasted a graft with SOC. Two of these studies (102
patients) contrasted an autograft with a dressing, three studies (80 patients)
contrasted a frozen allograft with a dressing, and two studies (45 patients)
contrasted a fresh allograft with a dressing. Two studies (345 patients)
contrasted a tissue-engineered skin (bilayer artificial skin) with a dressing.
In two studies (97 patients) a single-layer dermal replacement was contrasted
with SOC.

Six studies contrasted alternative skin grafting techniques. The first study
(92 patients) contrasted an autograft with a frozen allograft, a second study
(51 patients) contrasted a pinch graft (autograft) with a porcine dermis
(xenograft), the third study (110 patients) contrasted growth-arrested human
keratinocytes and fibroblasts with a placebo, the fourth study (10 patients)
contrasted an autograft delivered on porcine pads with an autograft delivered
on porcine gelatin microbeads, the fifth study (92 patients) contrasted a
meshed graft with a cultured keratinocyte autograft, and the sixth study (50
patients) contrasted a frozen keratinocyte allograft with a lyophilized
(freeze-dried) keratinocyte allograft.

Overall, the results show that substantially more ulcers healed when treated
with bilayer artificial skin than with dressings. There was inadequate
evidence from the other trials to establish whether other types of skin
grafting improved the healing of venous ulcers. The authors concluded that
bilayer artificial skin, used together with compression bandaging, improves
venous ulcer healing contrasted with a simple dressing plus compression.

It was noted that the overall quality of the studies reviewed was poor, thus
affecting the risk of inherent bias. Many of the studies did not convey
inclusion criteria, insufficient information was provided regarding
randomization techniques, and withdrawals and AEs were inadequately reported.
Deficient data regarding withdrawals and the inclination to perform per-
protocol analyses rather than intention-to-treat (ITT) analyses signify that
the outcomes in the original study documentation may be biased.17

**Clinical Trials for Skin Substitutes for Diabetic Foot Ulcers**

Barbul et al18 conducted a retrospective, matched-cohort study to establish
the efficacy of a cryopreserved human bioactive split-thickness skin allograft
(BSA) (i.e., TheraSkin) plus SOC when contrasted to SOC alone for the
treatment of diabetic ulcers. Data was obtained from electronic medical
records (EMRs) of an initial pool of 650,309 diabetic ulcers for patients
treated at 470 outpatient wound care centers in the U.S. from January 1, 2012
to October 25, 2018.

Primary inclusion criteria included: 1) Adults  18 years of age; 2) DFU,
Wagner grade 1-4 present for  30 days for individuals diagnosed with Type 1
or Type 2 diabetes; 3) Ulcer sited on foot, leg, or toe; and 4) Wound area  1
cm2 and  50 cm2. Primary exclusion criteria included: 1) Ulcers treated at
skilled nursing facilities; 2) Ulcers treated with advanced biological
products other than BSA; 3) Individuals in the control cohort who received any
cellular and/or tissue-based products; and 4) Individuals who showed  50%
closure of their wounds four weeks before the study treatment period.

Following elimination of ineligible patients and those missing important
information (i.e., wound characteristics) and/or lack of treatment
documentation, data included a total of 778 patients who were treated with the
BSA (treatment cohort) (mean age 65.67) and these study participants were
paired with 778 patients (mean age 62.95) drawn from a pool of 126,864
patients treated with SOC alone (control cohort), by utilizing propensity
matching to create almost identical cohorts. Complications and comorbidities
for both groups included Alzheimer's disease, coronary artery disease,
cellulitis, chronic obstructive pulmonary disease, congestive heart failure,
end stage renal disease, immunosuppressive conditions, morbid obesity,
peripheral vascular disease (arterial and venous), smoking status, and venous
insufficiency. Although the disparity in body mass index (BMI) improved with
propensity matching, a noteworthy difference remained between groups with
those in the BSA cohort having a substantially higher mean BMI than those in
the control cohort ( _p_ < 0.002).

Both cohorts received SOC treatment involving debridement, offloading, and
application of any kind of nonbiologic wound dressings, such as hydrogels,
saline-moistened gauze, and antimicrobial dressings. Study participants who
received a BSA may have utilized any or all of the same dressings.

Amputation rates and recurrence at 3 months, 6 months, and 1 year after wound
closure were analyzed. Diabetic ulcers were 59% more likely to close in the
treatment cohort contrasted to the control cohort ( _p_ =0.0045). The healing
rates with the BSA were greater than with SOC across multiple subsets, but the
most substantial improvement was noted in the worst wounds that had a duration
of 90-179 days prior to treatment ( _p_ =0.0073), exposed deep structures (
_p_ =0.036), and/or Wagner Grade 4 ulcers ( _p_ =0.04). Additionally, the
reduction in recurrence was substantial at 3 months, 6 months, and 1 year,
with and without initially exposed deep structures ( _p_ < 0.05). The
amputation rate in the treatment cohort was 41.7% less than that of the
control cohort at 20 weeks (0.9% vs. 1.5%, respectively). This study showed
that diabetic ulcers treated with a cryopreserved bioactive split-thickness
skin allograft were more likely to heal and stay closed contrasted to ulcers
treated with SOC alone.18

Cazzell et al19 performed a prospective, randomized, controlled, open-label
trial with a primary objective to contrast the healing rates of a human
decellularized acellular dermal matrix (D-ADM) for chronic DFUs with a SOC arm
and an active comparator, human acellular dermal matrix (ADM) arm for the
treatment of DFUs. Secondary objectives studied differences in time to wound
closure, economic burden, quality of life questionnaires and product
utilization between D-ADM, SOC, and a second active comparator human ADM.

Inclusion criteria included, but was not limited to: 1) Enrolled study
participants must have the capability to comply with offloading and dressing
change requirements; 2) The wound of focus must have been open and receiving
SOC for 30 days with an area  to 1 cm2 and < than 25 cm2; 3) Patient must be
between 21 and 80 years of age, have a single DFU of focus with a Wagner Ulcer
Classification Grade of 1 or 2, and no infection present; and 4) Patients must
have had acceptable circulation to the affected area, specified as having at
least one of the following criteria within the past 60 days: TCOM at the
dorsum of the foot  30 mmHg, ABI ranging from 0.8 - 1.2, or at least biphasic
Doppler arterial waveforms at the dorsalis pedis and posterior tibial
arteries.

Exclusion criteria included, but was not limited to: 1) Patient had wound
treatments including biomedical or topical growth factors within 30 days prior
to screening; 2) Patient had circulating HbA1c > 12% within 90 days of the
screening visit, serum creatinine concentrations of 3.0 mg/dL or > within 30
days before screening; 3) The presence of peripheral vascular disease, active
infection or untreated malignancy, Charcot's disease, or necrosis, purulence,
or sinus tracts unable to be removed by debridement; 4) Patient had a
revascularization procedure aimed at improving blood flow in the target limb,
or received a living skin equivalent within 4 weeks before screening; and 5)
Patient has a sensitivity to lincomycin, gentamicin, polymyxin B, vancomycin,
polysorbate 20, N-lauroyl sarcosinate, benzonase, or glycerol.

Patients with a diagnosis of diabetes mellitus on a stable treatment regimen
(no modifications in treatment for 30 days prior to screening) who visited the
clinic for care of a chronic lower extremity ulcer and met the above inclusion
criteria and none of the exclusion criteria were asked to join the study. In
this regard, the study enrolled 168 DFU patients in 13 centers across nine
states in the U.S. Patients were randomized into one of three treatment arms;
D-ADM (DermACELL), SOC wound management, or GJ-ADM (GraftJacketTM) at a ratio
of 2:2:1. The authors of this study indicated that the active comparator arm
for GJ-ADM was not intended to compare the difference between the ADMs as
several articles have reported the safety and efficiency of GJ-ADM; this arm
was added to the study to determine a baseline ADM healing rate.

Numbered envelopes holding the treatment designation were arranged by an
outside contract research organization and the study investigators were
blinded to the randomization codes matching each envelope. After a patient
successfully passed screening to be in the study, the investigator would open
the envelope to ascertain which randomized arm the patient was assigned to.
The ADM is visible upon application; therefore, it would have been impossible
to continue blinding the investigator once treatment was applied. Therefore,
as a secondary examination to avoid bias, a clinician, blinded to the
treatment arm assessed the wound images for confirmation of healing condition.

Initially, the wound beds were debrided with a sharp blade, scissors or
Versajet system to remove necrotic tissue for study participants in all three
treatment groups. Wound size was recorded using an imaging system pre-and
post-debridement as well as before dressing applications. The wound areas were
calculated by the imaging system and utilized for subsequent analysis of the
wound areas.

Patients in the D-ADM arm and the GJ-ADM arm had the appropriate ADM dressing
applied and covered with a nonadherent dressing. A second ADM was applied
between two weeks (at a minimum) and 12 weeks (at the latest) after the first
D-ADM application. Patients could have a maximum of two ADM applications,
which included the first application at baseline. Wounds in the conventional
care arm were provided with wound therapy involving alginates, foams, or
hydrogels. The treating provider then selected either a moist or dry gauze to
be placed over the wound. In all three treatment arms, the dressing covered
the wound for a minimum of 5 days, but no more than 9 days, (7 days  2 days)
until the next visit and dressings were only changed by the study team. Also,
during following weekly visits, debridement was used to remove necrotic
tissue, as needed. In addition, off-loading utilizing a removable cast walker,
diabetic shoe, surgical shoe, walker cast, or a total contact cast was
essential for all treatment arms unless the investigator considered it to be
inappropriate, such as situations involving a wheelchair bound patient or if
the wound was located on the dorsal surface of the foot. Though either
removable or nonremovable offloading techniques were permitted, 95% of all
patients used some type of removable method; 68% of patients used removable
boots and 16% of patients used surgical shoes.

Wounds were assessed on a weekly basis until wound closure was noted or the
patient completed 24 weekly follow-up visits. Wound closure was defined as
100% re-epithelialization of the wound without drainage. A second visit was
scheduled two weeks after the initial wound closure was noted to verify
complete wound closure. Additionally, all healed wounds were followed at 4, 8,
and 12 weeks after confirmation of complete wound closure to determine if the
wound remained healed.

A total of 168 patients were included in this study: 71 patients in the D-ADM
arm, 69 patients in the SOC arm, and 28 patients in the GJ-ADM arm. Patients
that withdrew from the study prematurely because of severe adverse events
(SAEs), which affected the ability to follow the wound of focus, offloading
non-compliance, or  25% missed visits involved 18 patients in the D-ADM arm,
13 patients in the SOC arm, and 5 patients in the GJ-ADM arm. To this end, 53
patients remained in the D-ADM arm and 40 of these patients received one
application, 56 patients remained in the SOC arm, and 23 patients remained in
the GJ-ADM arm and 16 of these patients received only one application. The
percentage of overall early withdrawals and the percentage of SAEs were
comparable between the three treatment groups based on relative population
size (p  0.05).

Baseline ulcer features, including wound size, were comparable between the
three ITT arms. The average age for patients in the D-ADM arm was 59.1, 56.9
in the SOC arm, and 58.5 in the GJ-ADM arm. The mean HbA1c at screening was
8.51% in the D-ADM arm, 8.38% in the SOC arm, and 7.63% in the GJ-ADM arm.
Patients diagnosed with Type 2 diabetes involved 93.5% of the enrolled
population, with 90.1% randomized to D-ADM, 97.1% randomized to SOC, and 92.9%
randomized to GJ-ADM. The treatments prescribed for diabetes control were
evenly dispersed across study arms, thus eliminating the potential confounding
effect of insulin levels on cell responses and healing. Also, it was noted
that almost half of the study participants (41.1%) were current or past
smokers and 58.9% had never smoked. Additionally, the majority of patients in
all three arms of the study had ulcers classified as Wagner class 2 (ulcers
that extend into tendon or capsule); D-ADM arm (83.1%), SOC arm (79.7%), and
GJ-ADM arm (82.1%).

Patients were followed for 24 weeks for all three treatment arms. Results for
the per protocol population showed that a single application of D-ADM showed a
substantially greater wound healing probability in comparison to SOC across
all three endpoints at Week 12 (65.0% vs. 41.1%; HR = 1.969; 95% CI = 1.1-3.5;
_p_ =0.0123), Week 16 (82.5% vs. 48.1%; HR = 2.397; 95% CI = 1.4-4.1; _p_
=0.0003), and Week 24 (89.7% vs. 67.3%; HR = 2.107; 95% CI = 1.3- 3.5;
p=0.0008). Patients in the D-ADM arm who received all applications also
demonstrated a substantially greater wound healing probability over SOC during
follow-up visits at Week 16 (67.9% vs. 48.1%; HR = 1.716; 95% CI =1.04-2.831;
_p_ =0.0283) and Week 24 (83.7% vs. 67.3%; HR = 1.546; 95% CI = 0.9821-2.435;
_p_ =0.0489). The patients in the D-ADM arm who received only one application
exhibited wound healing in an average of 9 weeks, whereas patients in the
conventional arm showed wound healing in an average of 16.5 weeks ( _p_
=0.0020). No substantial differences were observed between patients in the GJ-
ADM arm and patients in the SOC arm or between patients in the D-ADM and GJ-
ADM arms.

The SF-36 v2.0 (Optum, Inc.) was utilized to acquire the perception of general
health in eight areas for each study participant. The average, overall SF-36
scores at the end of the study were 425 for D-ADM, 430 for SOC, and 404 for
GJ-ADM. There were no substantial differences perceived between treatment arms
for the overall total score or in any of the eight areas. Also, a limitation
noted for this study indicates that the manufacturer of the D-ADM (DermACELL)
sponsored this trial.19

Driver et al20 conducted The Foot Ulcer New Dermal Replacement Study (FOUNDER)
to assess the safety and effectiveness of the Integra Dermal Regeneration
Template (IDRT) (i.e., Omnigraft Dermal Regeneration Matrix) for the
treatment of nonhealing DFUs. The study was a multicenter, randomized,
controlled, parallel group clinical trial performed under an Investigational
Device Exemption. This study was designed based on guidelines from the FDA for
creating products to treat chronic cutaneous ulcers. The FOUNDER study
involved 32 clinical sites and 307 patients that were randomized into two
parallel groups.

The primary inclusion criteria included: 1) Established Type 1 or Type 2
diabetes with a HbA1c  12%; 2) Patients  18 years of age; 3) Presence of a
full-thickness neuropathic ulcer positioned distal to the malleolus; 4) The
ulcer of focus must have been in existence for greater than 30 days with the
ulcer area between 1 and 12 cm2 post-debridement; and 5) Satisfactory vascular
perfusion as defined by ABI  0.65 and  1.2 or toe pressure > 50 mmHg or
transcutaneous oxygen pressure (TcPO2) > 40 mmHg or doppler ultrasound
consistent with sufficient blood flow to the affected extremity.

The primary exclusion criteria were active infection involving osteomyelitis,
exposed capsule, tendon, or bone, and reduction of wound  30% during the
screening interval. The trial was separated into three phases: screening/run-
in, randomization/treatment, and follow-up. Patients entered the
screening/run-in phase after providing written consent and underwent a series
of screening evaluations and a 14-day run-in period in which patients received
SOC treatment on the ulcer of focus to establish eligibility for the study.
The following procedures were performed during the run-in period for the ulcer
of focus: 1) Infection and exudate evaluation; 2) Sharp debridement; 3)
Measurement of the deepest aspect (post-debridement); 4) Photograph (pre- and
post-debridement); 5) Tracing for planimetric evaluation (post-debridement);
6) SOC that involved sharp debridement followed by application of a moist
wound therapy consisting of 0.9% sodium chloride gel and a secondary dressing
involving a nonadherent foam dressing, an outer gauze wrap, and an
offloading/protective device (i.e., Active Offloading Walker [boot and/or
shoe]); and 7) Patients were instructed on the SOC treatment for daily
dressing changes.

Other patient evaluations conducted during the run-in period included: A
medical history; medication usage; therapies; physical examination; and
neuropathic, laboratory, and vascular perfusion assessments. Once the patients
completed the screening/run-in phase, patients were then assessed to determine
continued satisfaction of eligibility criteria. The ulcer of focus was then
debrided using sharp debridement prior to the first treatment. Also, a
planimetric evaluation was performed (blindly by a central laboratory).

Patients with study ulcers that had healed < 30% in the run-in period were
randomized using a software algorithm at a central location in mixed blocks of
2 and 4 in a 1:1 ratio to the active or control treatment. Randomization was
stratified by study location and wound size ( 3 cm2 versus > 3 cm2).
Treatment started on the day of randomization as assigned and the treatment
phase continued until the patient had 100% wound closure or for up to 16
weeks. The SOC was the control treatment and the IDRT was the active
treatment. The SOC treatments were just as described in the screening/run-in
phase and daily dressing changes were done either by the patient in the
control group or by a trained caregiver.

For the active treatment group, fenestrating and meshing of the IDRT was
acceptable to allow for drainage and in the presence of exudating wounds or
hematomas. The IDRT was placed on the debrided wound, trimmed to size, and
secured with sutures or staples, and covered with a secondary dressing. When
the collagen layer was replaced by new tissue, typically in 14 to 21 days
after application, the silicone layer of the IDRT was removed. Re-applications
of the IDRT were done as deemed necessary by the investigator. The site
personnel performed the secondary dressing changes for the active treatment
group on a weekly basis.

Wounds were assessed on a weekly basis during the treatment phase or until
wound closure was noted. A visit was scheduled one week after the initial
wound closure was noted to verify complete wound closure. An additional visit
was then scheduled for confirmation of wound closure. Following completion of
the treatment phase, all patients were followed every four weeks during the
12-week follow-up phase.

Complete closure of the ulcer of focus during the treatment phase (16 weeks)
(defined as 100% re-epithelialization of the wound surface with no discernable
exudate and without drainage or dressing needs), was substantially greater in
the active group (51%; 79/154) in contrast to the control group (32%; 49/153,
_p_ =0.001). Comparable results were observed when wound closure was evaluated
by computerized planimetry: 50% (77/154) in the active group and 31% (48/153)
in the control group ( _p_ =0.001). The probabilities of complete wound
closure established at the end of the treatment phase were 2.2 times higher
(95% CI = 1.4, 3.5; _p_ =0.001) for the active group contrasted with the
control group. Assessment using planimetric data to evaluate wound closure was
consistent with an odds ratio of 2.2 (95% CI = 1.3, 3.5; _p_ =0.001). When
complete wound closure was evaluated at 12 weeks, the results were
substantially different between the two groups (45% active [70/154] vs. 20%
control [31/153]; _p_ < 0.001). The probabilities of complete wound closure at
12 weeks were 3.3 times higher (95% CI = 2.0, 5.4; _p_ < 0.001) for the active
group contrasted with the control group. The average number of applications
per individual, including the initial application, for the active group was 1
(range 1-15).

The degree of decrease in wound size was 7.2% per week for the active group
vs. 4.8% per week for the control group ( _p_ =0.012). At the end of the
follow-up phase, ulcer recurrence was experienced by 19% of the active
treatment group and by 26% of the control treatment group ( _p_ =0.32).
Quality of life data demonstrated substantial improvements in physical
functioning ( _p_ =0.047) and bodily pain ( _p_ =0.033) for the active group
contrasted with the control group.

Most AEs in both groups were mild. Severe AEs were incurred by 15.6% of
patients in the active group and by 26.8% in the control group ( _p_ =0.016).
Moderate AEs were incurred by 31.8% of patients in the active group and by
42.5% of patients in the control group ( _p_ =0.053). The AEs possibly linked
to study treatment were comparable in both treatment groups (7/154 [4.5%] in
the active group vs. 8/153 [5.2%] in the control group). Also, a limitation
noted for this study is the manufacturer of the IDRT used in the active
treatment group sponsored this trial.20

Lavery et al21 performed a prospective, multi-center, randomized, single-
blinded study to contrast the effectiveness of a human viable wound matrix
(hVWM) (i.e., Grafix) to standard wound care in treating chronic DFUs from
May 2012 to April 2013. The primary outcome was the percentage of patients
with complete wound closure by 12 weeks. Complete wound closure was defined as
100% re-epithelialization with no wound drainage. Secondary outcomes
encompassed the time to wound closure, AEs, and wound closure in a crossover
phase.

Primary inclusion criteria included: 1) Established Type 1 or Type 2 diabetic
patients 18-80 years of age; 2) Diabetic ulcer present for 4 to 52 weeks; and
3) Diabetic ulcer positioned below the malleoli on the plantar or dorsal
surface of the foot and ulcer 1 to 15 cm2 in size. Primary exclusion criteria
included: 1) HbA1c above 12%; 2) Indication of active infection, including
osteomyelitis or cellulitis; 3) Insufficient circulation to the affected foot
defined by an ABI < 0.70 or > 1.30, or toe brachial index  0.50 or Doppler
study with insufficient arterial pulsation; 4) Exposed muscle, tendon, bone,
or joint capsule; and 5) Decrease of wound area by  30% during the screening
period.

After a 1-week screening period, patients were randomized to the active
treatment arm (i.e., hVWM) or control treatment arm (i.e., standard wound
care) in a 1:1 ratio. Patients in the active treatment group received an
application of hVWM once a week ( 3 days) for up to 84 days (blinded
treatment phase). Patients in the control group received SOC wound therapy
once a week ( 3 days) for up to 84 days and wounds were cleaned and
surgically debrided to remove all non-viable soft tissue from the wound by
scalpel, tissue nippers and/or curettes at each weekly visit.

Wounds in both groups received SOC that involved surgical debridement, off-
loading and non-adherent dressings and either saline moistened gauze or an
absorbent foam dressing for moderately draining wounds. Also, an outer
dressing was applied. In addition, walking boots were provided for patients
with wounds on the sole of the foot and post-op shoes were provided for
patients with wounds on the dorsum of the foot or at the ankle.

Patients were evaluated weekly at the clinical site. Patients who attained
complete wound closure then continued to be assessed during the follow-up
phase, twice during the first month and then monthly for two additional
visits. Patients in the control group whose wounds were not closed by the end
of the blinded treatment phase were able to receive the hVWM in the open-label
treatment phase, in which the hVWM was applied weekly for up to 84 days.

During screening, 139 patients were assessed. A total of 42 patients failed
screening and of these, 6 were excluded due to a decrease of their wound areas
by  30% during the screening period. A total of 97 patients were randomized:
50 to the active treatment arm and 47 to the control arm.

The percentage of patients who attained complete wound closure was
substantially higher in the active treatment group (62%) compared with the
control group (21%, _P_ =0.0001). The average time for healing was 42 days in
the active treatment arm contrasted with 69.5 days in the control arm ( _P_
=0.019). There were less AEs in the active arm (44% versus 66%, _P_ =0.031)
and less wound-related infections (18% versus 36.2%, _P_ =0.044). Among the
study participants that healed, ulcers remained closed in 82.1% of patients
(23 of 28 patients) in the active group versus 70% (7 of 10 patients) in the
control group ( _P_ =0.419). The authors concluded that treatment with the
hVWM substantially improved DFU healing contrasted with SOC therapy. Also, a
limitation noted for this study is the manufacturer of the hVWM used in the
active treatment group sponsored this trial.21

Sanders et al22 performed a prospective, multi-center, randomized, controlled
trial to contrast an in vitro-engineered, human fibroblast-derived dermal skin
substitute (HFDS) (i.e., Dermagraft) to a biologically active cryopreserved
human skin allograft (HSA) (i.e., TheraSkin) in the treatment of DFUs. The
primary objectives were to establish the relative number of DFUs healed (100%
epithelization without drainage) and the number of grafts needed by week 12.
Secondary objectives involved the percentage of DFUs healed at weeks 16 and
20, time to heal during the study and wound size progression.

Primary inclusion criteria included: 1) Established Type 1 or Type 2 diabetic
patients > 18 years of age; 2) HbA1C < 12%; 3) Full-thickness foot ulcer
existing > 30 days; 4) Ulcer > 1 cm2 and < 10 cm2 in size with at least 2 cm
between study ulcer and other ulcers; and 5) ABI > 0.65, toe pressure > 50
mmHG, and TcPO2 > 20 mmHG. Primary exclusion criteria included: 1) Wound
infection or gangrene of the foot; 2) Patient has received oral or parenteral
corticosteroids, immune-suppressive or cytotoxic drugs within the last 12
months; and 3) Treatment with growth factors or bioengineered skin substitutes
within the past 30 days.

A total of 23 patients participated in the study at two hospital-based wound
care centers in three phases. During the first phase, screening was performed,
and eligible patients were randomly assigned to the HFDS treatment group (12
patients) (mean age 57) or the HSA treatment group (11 patients) (mean age 60)
using a series of sealed envelopes employing a block randomization technique
that described the treatment to be applied. During the second phase (one week
later), the treatment phase started and continued for 12 weeks. All wounds
(both groups) were debrided to remove nonviable tissue and callous from the
wound surface and adjacent wound perimeter and then cleansed with saline.
Afterwards, the initial application of the biologically active product was
applied as randomly assigned and all wounds were then covered with a non-
adherent dressing and were offloaded with 1/2 inch felt as part of an aperture
type of device. All patients were then given a healing sandal developed from a
surgical shoe or a fixed ankle boot.

Patients in the HSA group received a product application every other week and
patients in the HFDS group were treated every week with wounds prepared as
described above prior to application of the product. Since both products have
a distinctive appearance, it was not possible to conceal the type of product
used during wound assessments. Wounds were photographed at each visit and the
margins of the wounds were traced along the inner edge of the margins.

At week 12, patients with an unhealed wound continued into the third phase
(follow-up) for treatment and assessment for up to eight more weeks. After the
week 12 visit, no additional biologically active products were used in either
treatment group. In this phase, wounds were treated with saline-moistened
gauze and debridement as needed.

Patients with ulcers verified to be healed were scheduled for a confirmatory
visit. Patients with incomplete wound closure continued to be evaluated though
week 20; subsequent treatment was then provided outside the scope of the
study.

There were no substantial differences discerned between patient demographics
and wound attributes at baseline in the two treatment groups. At week 12,
seven (63.6%) wounds in the HSA treatment group versus four (33.3%) in the
HFDS treatment group were healed (P=0.0498). At the end of week 20, 90.91% of
wounds in the HSA group versus 66.67% of wounds in the HFDS group were healed
(P=0.4282). Among the subset of wounds that healed during the first 12 weeks
of treatment, a mean of 4.36 (range 2-7) HSA grafts were applied versus 8.92
(range 612) in the HFDS subset group (P < 0.0001, SE 0.77584). Time to
healing in the HSA group was substantially less (8.9 weeks) than in the HFDS
group (12.5 weeks) (log-rank test, P=0.0323). The results of this study showed
that, after 12 weeks of care, DFUs treated with HSA are probably twice as
likely to heal as DFUs managed with HFDS with about half the number of grafts
required. Limitations noted for this study are the small sample size and the
manufacturer of the HSA product used in one of the active treatment groups
sponsored this trial.22

Zelen et al23 performed a prospective, randomized, controlled, multicenter
study to evaluate the healing rates, safety, and cost using an open-structure
human reticular acellular dermis matrix (HR-ADM) (i.e., AlloPatch PliableTM)
plus SOC to facilitate wound closure in DFUs compared to treatment with SOC
alone. The trial was conducted from December 2014 to November 2015 at five
outpatient wound care centers in Virginia and Ohio.

Primary inclusion criteria included: 1) Patients with Type 1 or Type 2
diabetes with a non-healing neuropathic foot ulcer that failed a minimum of 4
weeks of documented conservative care; 2) Adequate renal function as shown by
a serum creatinine level < 3.0 mg/dl; and 3) Sufficient circulation to the
affected extremity within the past 60 days as evidenced by TCOM with result 
30 mmHg, ABI with result of  0.7 and  1.2 or Doppler arterial waveforms,
which were triphasic or biphasic at the ankle of the affected leg.

All eligible patients meeting inclusion and exclusion criteria were treated
with SOC alone, which included surgical debridement, for a 2-week screening
period and patients whose index wound had not healed greater than 20% at 2
weeks were then considered eligible for the study. A total of 40 study
participants were eligible for enrollment in the study and were randomized to
HR-ADM plus SOC ( _n_ = 20) (HR-ADM applications weekly) or SOC alone ( _n_ =
20) (daily dressing changes). There were no significant group differences
regarding patient and wound attributes, with the exception of the average
wound area, which was larger in the HR-ADM group (4.7 cm2) contrasted with the
SOC group (2.7 cm2).

The primary outcome of this study focused on a comparison of wound healing at
6 weeks using HR-ADM plus SOC versus SOC alone. Wounds were considered as
healed if there was complete (100%) re-epithelization with no drainage and no
need for a dressing. Secondary outcomes involved comparing healing at 12
weeks, time to heal at 6 and 12 weeks, graft count, wastage, and assessment of
product cost to closure. An ITT method was utilized for all analyses. At 6
weeks, 65% (13/20) of the HR-ADM-treated ulcers had healed contrasted with 5%
(1/20) of the ulcers treated with SOC alone ( _P_ =0.00028). The decrease in
the wound area size between the groups changed significantly over time, with
an average time to heal within 6 weeks of 28 days (95% CI: 22-35 days) for the
HR-ADM group contrasted with 41 days (95% CI: 40-43 days) for the SOC group.
After adjusting for area of wound at randomization, the hazard ratio (HR) for
HR-ADM contrasted with SOC was 168 (95% CI: 10-2704), _P_ =0.00036. Ten study
participants from the SOC group (50%) and one patient from the HR-ADM group
(5%) discontinued the study at 6 weeks per protocol as their wound failed to
decrease in area by at least 50%.

At 12 weeks, 80% (16/20) of the HR-ADM-treated ulcers had healed contrasted
with 20% (4/20) of the ulcers treated with SOC alone (P=0.00036). The average
time to heal within 12 weeks was 40 days (95% CI: 27-52 days) for the HR-ADM
group contrasted with 77 days (95% CI: 70-84 days) for the SOC group ( _P_
=0.00014).

The average number of HR-ADM grafts used to achieve closure per ulcer was 4.7
(SD=3.3). The average percentage of wastage (healed wounds only) was 51.7%
(SD: 10.7; _n_ = 16). There was no occurrence of increased AEs or SAEs between
groups, or any AEs related to the graft. This study concluded that the use of
HR-ADM plus SOC is more effective in the treatment of DFUs than with SOC
alone. This study was limited by the patients unblinded to treatment
allocation and the study was also funded by the manufacturer of the HR-ADM
graft.23

**Clinical Trials for Skin Substitutes for Venous Leg Ulcers**

Cazzell24 conducted a multicenter, randomized, controlled, open-label trial
designed to evaluate the safety and efficacy of human decellularized acellular
dermal matrices (D-ADM) contrasted with SOC management in patients with
chronic VLUs. This exploratory pilot study included eight implanting surgeons
from seven medical centers in five states that enrolled patients with VLUs.
The study participants were randomly assigned to the D-ADM (i.e., Dermacell
AWM) treatment arm or a SOC treatment arm in a 2:1 ratio. Numbered envelopes
holding the treatment designation were arranged by an outside contract
research organization and the study investigators were blinded to the
randomization codes matching each envelope. After a patient successfully
passed screening to be in the study, the investigator would open the envelope
to ascertain which randomized arm the patient was assigned to. The D-ADM is
visible upon application; therefore, it would have been impossible to continue
blinding the investigator once treatment was applied. Therefore, as a
secondary examination to avoid bias, a blinded, independent adjudicator also
assessed the healing condition of all wounds.

Primary inclusion criteria included: 1) Adults  21 and  80 years of age; 2)
Presence of a single target VLU with a CEAP ulcer classification Grade 6; 3)
Duration of the target VLU  60 days; 4) Absence of infection; 5) VLU area  1
cm2 and < 25 cm2, depth  9 mm; and 6) Able to comply with offloading and
dressing change stipulations.

Primary exclusion criteria included: 1) HbA1c < 12% within 90 days of
screening visit; 2) Serum creatinine  3.0 mg/dL within 30 days of screening;
3) Application of biomedical, topical growth factors or living skin
equivalents to the target VLU within 30 days of screening; 4) Recent
revascularization procedure to increase blood flow in the target limb; 5)
Sensitivity to possible D-ADM processing reagents (e.g., gentamicin, polymyxin
B, vancomycin, N-lauroyl sarcosinate, Benzonase, glycerol); and 6)
Manifestation of severe peripheral vascular disease, active infection,
untreated malignancy, active Charcot's disease, necrosis, purulence, or sinus
tracts in the ulcer unable to be removed by debridement.

Eighteen patients were included in the D-ADM arm (mean age 64.6) and 10
patients in the control arm (mean age 61.8). Initially, all wounds for both
groups were debrided to remove necrotic tissue utilizing a sharp blade,
scissors, or Versajet system. Wound size was recorded using an imaging system
pre-and post-debridement as well as before dressing application. Patients in
the treatment arm had the D-ADM applied and covered with a nonadherent
dressing. A second D-ADM was applied between two weeks (at a minimum) and 12
weeks (at the latest) after the first D-ADM application. Patients could have a
maximum of two D-ADM applications, which included the first application at
baseline.

Wounds in the SOC arm were provided with wound therapy involving alginates,
foams, or hydrogels. The treating provider then selected either a moist or dry
gauze to be placed over the wound and left in place for 7  2 days, which was
only to be removed during weekly visits. During the weekly visits, debridement
was used to remove necrotic tissue, as needed.

Compression therapy was used in the treatment and control arms. Wounds were
assessed on a weekly basis until wound closure was noted or the patient
completed 24 weekly follow-up visits. Wound closure was defined as 100% re-
epithelialization of the wound without drainage. A second visit was scheduled
two weeks after the initial wound closure was noted to verify complete wound
closure. Additionally, all healed wounds were followed at 4, 8, and 12 weeks
after confirmation of complete wound closure to determine if the wound
remained healed.

The primary outcome of the study contrasted the full wound closure rates
between the two groups. The second outcome of the study involved contrasting
the decrease in wound size over time, time to wound closure, and treatment-
related AEs. Twenty-eight patients completed at least 12 weeks of follow-up;
18 patients in the D-ADM arm and 10 in the SOC arm. Of the 18 patients
receiving the D-ADM, nine (50%) received a second application during the
study. At 24 weeks, patients in the D-ADM arm demonstrated a strong trend of
reduction in the wound area, with a mean reduction of 59.6%, in comparison to
the SOC arm, with a mean reduction of 8.1%. Also, the wound areas in the SOC
arm increased more than 100% in size for one-third (3/9) of the patients.
Furthermore, healed ulcers in the D-ADM arm stayed closed at a significantly
greater rate after initial confirmation of complete wound closure than healed
ulcers in the control arm. Limitations noted for this study included a small
patient population with an unbalanced proportion between the 2 groups (2:1)
that ensured a low probability of achieving statistical significance, the lack
of blinding for the study investigators, and the study was funded by the
manufacturer of the D-ADM graft.24

Harding et al25 conducted an open label, prospective, multicenter, randomized
controlled study that assessed the human fibroblast-derived dermal substitute
(HFDS) (i.e., Dermagraft) in addition to four-layer compression therapy
contrasted with compression therapy alone in the treatment of VLUs. The
primary outcome variable was the proportion of patients with completely healed
study ulcers by 12 weeks. Complete healing was characterized by having a
closed wound (with full epithelization and no exudate or scab) for two
consecutive weekly visits.

Primary inclusion criteria included: 1) Individuals  18 years of age referred
to participating facilities/clinics in the United Kingdom (UK), Canada or the
U.S.; 2) Presence of a VLU between the knee and ankle existing for at least 2
months and  5 years prior to screening; 3) Size of VLU 3-25 cm2 without
exposure of muscle, tendon or bone; 4) Presence of a clean, granulating base
with negligible adherent slough, suitable for a skin graft; and 5) ABI of 0.8
to 1.2 and reflux of > 0.5 seconds in saphenous, calf perforator or popliteal
veins as confirmed by duplex ultrasonography.

Primary exclusion criteria included: 1) Individuals with ulcers caused by a
medical condition other than venous insufficiency; 2) Presence of sinus tracts
in ulcer; 3) Signs of a wound infection (purulence and/or odor), cellulitis
and/or verified osteomyelitis; 4) Morbid obesity; 5) Skin disease near study
ulcer; 6) Malignant disease within the past 5 years; and 7) Severe peripheral
vascular disease or renal disease, congestive heart failure, cell anemia,
thalassemia or uncontrolled diabetes. Also, individuals who had received
immune suppressants, systemic corticosteroids, cytotoxic chemotherapy, or
topical steroids for more than 2 weeks and within one month of initial
screening or who had a history of radiation at the ulcer site were not
eligible to participate in the study. In addition, patients who had received
an investigational drug within 30 days of randomization or had been previously
treated with an HFDS and/or other tissue-engineered materials were also
excluded from the study.

All patients received a SOC dressing treatment during the screening period;
each ulcer was covered with a layer of non-adherent dressing followed by a
four-layer compression bandage. During the 2-week screening period, ulcers
were evaluated weekly to establish absence of necrotic tissue and infection
and the presence of a vascular bed. Ulcers that decreased in size (cm2) by <
50% while under compression therapy during the 2-week screening period for the
trial were eligible for randomization into the study.

Of the 573 patients screened, 207 failed screening (36%). The primary causes
for screening failure were study ulcers decreasing in size by more than 50%
during screening, study ulcers less than 3 cm2 at randomization and patients
without indication of venous reflux. The remaining 366 patients were
randomized to receive treatment at a total of 25 centers: 19 in the UK, 1 in
Canada and 5 in the U.S. The ITT population (patients who received treatment
at baseline and had a follow-up visit post-baseline) included 186 patients in
the HFDS group and 180 patients in the control group with a mean age of 68.5
years. Patients were randomized to receive an application of HFDS plus the
four-layer compression bandage therapy (active) or the four-layer compression
bandage therapy alone (control). Patients randomized to the active treatment
group received the HFDS applied to the wound at weeks 0, 1, 4 and 8.

A total of 10% (19 of 186) of patients in the HFDS group discontinued the
trial early contrasted with 23% (41 of 180) of patients in the control group.
The causes for early discontinuation were AEs (3% in the HFDS group versus 6%
in the control group), patient's own request (2% versus 9%), patient lost to
follow-up (2% versus 3%) and 'other' (4% from each group).

Sixty-four (34%) of 186 patients in the HFDS group demonstrated healing by
week 12 contrasted with 56 (31%) of 180 patients in the control group
(P=0.235). For ulcers  12 months duration, 49 (52%) of 94 patients in the
HFDS group contrasted with 36 (37%) of 97 patients in the control group healed
at 12 weeks (P=0.029). For ulcers  10 cm2, complete healing at week 12 was
shown in 55 (47%) of 117 patients in the HFDS group contrasted with 47 (39%)
of 120 patients in the control group (P=0.223). The most common AEs were wound
infection, cellulitis, and skin ulcer. The occurrence of AEs was not
significantly different between the treatment and control groups. Statistical
significance was not achieved for the primary outcome of patients with VLUs
completely healed by 12 weeks. Also, a limitation noted for this study is the
manufacturer of the HFDS used in the control group helped sponsor this
trial.25

**Frequency**

There is paucity of evidence to address how frequently skin substitutes should
be reapplied. Few studies include the frequency of applications. A
retrospective review by Caputo et al. reported seventy-eight percent of
complex wounds achieved complete closure, with a median time-to-heal of 16
weeks using an average of 1.24 applications of NEOX Wound Allograft. Couture
reported using an average of 3.43 NEOX applications with an average healing
time of 5.53 weeks in a single-center retrospective study. A retrospective
chart review by Raphael reported median time to heal 13.79 weeks with an
average 1.68 applications. Armstrong and colleagues presented a retrospective
analysis at the 2021 Wounds UK annual Conference reporting skin substitutes
were applied every 7-14 days. While this is not peer-reviewed literature, and
included authors who are paid speakers for MIMEDX, it is being included based
on the patient population and lack of other evidence.

****

**Societal Input**

****

**National Institute for Health and Care Excellence (NICE) Diabetic foot
problems: prevention and management**

The clinical guideline on diabetic foot problems considers dermal or skin
substitutes as an adjunct to standard care when treating diabetic foot ulcers
only when healing has not progressed and on the advice of the
multidisciplinary foot care service. (NICE, published 2015; Updated October
2019).

**International Working Group on the Diabetic Foot (IWGDF)**

IWGDF recommends the consideration of placental-derived products as an
adjunctive treatment to the best standard of care when standard care alone has
failed to reduce the size of the wound. (GRADE Strength of recommendation:
Weak; Quality of evidence: Low). This was based on a number of studies,
including those of moderate bias, suggesting that placenta-derived products
may have a beneficial effect on ulcer healing, but the authors also state that
these findings need to be confirmed in large, randomized trials. They state
there is insufficient evidence to support superiority of any particular
products.

For use of topically applied treatments, the IWGDF recommends against the use
of bioengineered skin products in comparison to standard of care.

For both of these recommendations, the IWGDF considered the available evidence
to be of low quality, and their recommendation was weak (i.e., based on the
quality of evidence, balance between benefits and harms, patient values and
preferences, and cost or resource utilization).

**Wound Healing Society (WHS)**

The WHS has published updated evidence-based guidelines on the treatment of
diabetic ulcers. Regarding the use of skin substitutes, the WSH concluded that
level I evidence suggests that cellular and acellular skin equivalents improve
the healing of diabetes-related foot ulcers. In these guidelines Level I
required at least two RCT supporting the intervention of the guidelines. The
quality of evidence was not assessed (Lavery et al., 2016). 32

_In evidence-based guideline for venous ulcers, the WHS stated that there is
evidence that a bilayered living human skin equivalent, used in conjunction
with compression bandaging, increases the incidence and speed of healing for
venous ulcers compared with compression and a simple dressing (Level I
evidence). The WHS recommends adequate wound bed preparation and control of
excess bioburden levels prior to application of a biologically active
dressing. They also noted that cultured epithelial autografts or allografts
have not been demonstrated to improve stable healing of venous ulcers (Level
I). The WHS also stated that there is Level II evidence that a porcine small
intestinal submucosal construct may enhance healing of venous ulcers (Marston
et al., 2016)._ 33

**Society for Vascular Surgery/American Podiatric Medical Association/Society
for Vascular Medicine (SVS/APMA/SVM)**

The SVS/APMA/SVM published a joint evidence-based guideline using Grades of
Recommendation Assessment, Development, and Evaluation system for the
management of patients with diabetes, including treatment of diabetes related
chronic foot ulcers (Hingorani et al., 2016). 34

  * These organizations recommendations for diabetic foot ulcers that fail to demonstrate improvement (> 50% wound area reduction) after a minimum of 4 weeks of standard wound therapy, adjunctive wound therapy options include negative pressure therapy, biologics (platelet-derived growth factor, living cellular therapy, extracellular matrix products, amniotic membrane products) and hyperbaric oxygen therapy. The choice of adjuvant therapy is based on clinical findings, availability of therapy, and cost-effectiveness; there is no recommendation on ordering of therapy choice (Grade 1B).
  * Consideration of living cellular therapy using a bilayered keratinocyte/fibroblast construct or a fibroblast-seeded matrix for treatment of diabetic foot ulcers when the individual is recalcitrant to standard therapy (Grade 2B).
  * Consideration of the use of extracellular matrix products employing acellular human dermis or porcine small intestinal submucosal tissue as an adjunctive therapy for diabetic foot ulcers when the individual is recalcitrant to standard therapy (Grade 2C).

Chronic wounds can be very challenging for the provider as well as the patient
and are described as wounds unable to re-epithelialize after one to three
months of treatment. These wounds include vascular ulcers (e.g., venous and
arterial), diabetic ulcers, and pressure ulcers and affect patient quality of
life due to impaired mobility, pain, and substantial morbidity.

Standard treatment of lower extremity chronic wounds includes, but is not
limited to, mechanical offloading, infection control, mechanical compression,
limb elevation, debridement of necrotic tissue, management of systemic disease
and medications, nutrition assessment, tissue perfusion and oxygenation,
appropriate dressings, education regarding the care of the foot, callus, and
nail and fitting of shoes, and counseling on the risk of continued tobacco
use.

Nonhealing lower extremity ulcers should also have a vascular evaluation,
including, but not limited to, documentation of wound location, size, depth,
drainage, and tissue type; palpation of pedal pulses; and measurement of the
ankle-brachial index.

In the absence of underlying disease or non-adherence to prescribed basic
treatment, skin substitute grafts are recommended in accordance with evidence-
based guidelines for the following: 1) DFUs that have failed to demonstrate
more than 50% wound area reduction after a minimum of four weeks of standard
wound care measures, and 2) VLUs if substantial wound improvement is not
demonstrated after a minimum of four to six weeks of standard wound care
measures.

An extensive variety of wound care products are available for providers to
select from when treating chronic wounds. Many of these products may simulate
or substitute for some aspect of the skin's structure and function to promote
healing and wound closure. The materials used to create these products may be
derived from human or animal tissue and may undergo extensive or minimal
processing to generate the finished product. The degree of processing and the
source of the material used in the product also governs which regulatory
pathway may be required before the product may be marketed.

The regulation of tissue-engineered products in the U.S. occurs by one of
several pathways established by the FDA, including a BLA, a 510(k) (Class I
and Class II devices), PMA (Class III devices), or HCT/Ps (human cells,
tissues, and cellular and tissue-based products) designation. Key
differentiators among these regulatory classifications include the amount and
type of data required to support a filing.

Amniotic/chorionic-based products that are HCT/Ps as defined in 21 CFR
1271.3(d) must meet criteria in 21 CFR 1271 and 361 of the PHS Act.
Manufacturers of HCT/Ps should consult with the FDA Tissue Reference Group
(TRG) or obtain a determination through a Request for Designation (RFD) on
whether their HCT/Ps are appropriately regulated solely under section 361 of
the PHS Act and the regulations in 21 CFR Part 1271 (85 FR 86058). The HCT/Ps
that are drugs are defined under section 201(g) of the Federal FD&C Act [21
U.S.C. 321(g)] and biological products are defined in section 351(i) of the
PHS Act [42 U.S.C. 262(i)]. To lawfully market a drug that is also a
biological product, a valid biologics license must be in effect [42 U.S.C.
262(a)]. Such licenses are issued only after a showing of safety and efficacy
for the product's intended use. While in the development stage, such products
may be distributed for clinical use in humans only if the sponsor has an
investigational new drug (IND) application in effect as specified by FDA
regulations [21 U.S.C. 355(i); 42 U.S.C. 262(a)(3); 21 CFR Part 312].

The HCT/Ps which are more than minimally manipulated, or are intended for non-
homologous use, may be subject to additional regulation as medical devices
under the Federal Food, Drug and Cosmetic Act (FDCA), 21 U.S.C. section 301 et
seq. (see 21 CFR section 1271.20). A manufacturer/distributor of HCT/Ps must
register with the FDA as a "tissue establishment" and follow certain
guidelines for designation of a product as an HCT/P (21 CFR sections 1271.10;
1271.21-22). The FDA imposes labeling requirements for HCT/Ps (refer to 21 CFR
section 1271.370). The HCT/P labeling must include, inter alia, "instructions
for use when related to the prevention of the introduction, transmission, or
spread of communicable diseases," and "other warnings, where appropriate" (21
CFR section 1271.370(c)(3)-(4)).

The FDA acceptance of an establishment registration and HCT/P listing does not
constitute a determination that an establishment is in compliance with
applicable rules and regulations or that the HCT/P is licensed or approved by
the FDA (21 CFR 1271.27(b)). To establish compliance with the FDA requires a
letter from the FDA indicating that the HCT/P has met regulatory compliance
under section 361 of the Public Health Service Act and/or the Federal Food,
Drug, & Cosmetic Act.

It is recommended that the manufacturer of the particular skin substitute
graft or CTP product obtain the appropriate information and send to the MAC
along with evidence-based literature, if available. Once this information has
been received by the MAC, the product will be considered for coverage and
placed into the appropriate Code Group in the associated article. The
literature would support the medially reasonable and necessary criteria for
the product(s).

Studies are lacking for many wound care products (e.g., skin substitutes)
which are essential to evaluate effectiveness and the impact that the product
has on health outcomes. Available studies do not have a high level of evidence
or even non-randomized prospective studies evaluating their effectiveness. The
quality of current research for these products is moderate to low with high
probability of publication bias and study limitations. Evidence is needed to
show that the product(s) improve health outcomes or provide benefits relative
to established alternatives or standard of care. Many of the current studies
are noted to be funded by industry, which presents concerns regarding bias for
these studies.

Despite the lack of studies, the moderate to low quality of current research
and the likelihood of bias, coverage has been provided to increase the chances
of improved health outcomes of interest which include patient quality of life
and function. Coverage will be provided for products in the associated billing
and coding guideline meeting the necessary FDA regulatory requirements as of
publication. Each product has specific designated approved usage. New products
will be considered for coverage if meeting the regulatory requirements and
criteria. Satisfactory evidence of FDA regulatory requirements include: 1) A
copy of the FDA's letter to the drug's manufacturer approving the new drug
application (NDA), 2) A listing of the drug or biological in the FDA's
"Approved Drug Products" or "FDA Drug and Device Product Approvals", 3) A copy
of the manufacturer's package insert approved by the FDA as part of the
labeling of the drug, containing its recommended uses and dosage, as well as
possible adverse reactions and recommended precautions in using it, or 4)
Information from the FDA's Website. For skin substitutes classified as HCT/Ps,
a letter from the FDA indicating that the HCT/P has met regulatory guidance is
acceptable evidence of the FDA regulatory compliance for HCT/Ps regulated
under section 361 of the Public Health Service Act and/or the Federal Food,
Drug, and Cosmetic Act.