# SUMMARY OF SAFETY AND EFFECTIVENESS DATA

# 

# 

# I. GENERAL INFORMATION

**[Device Generic Name]{.underline}**: filler, recombinant human bone
morphogenetic protein, collagen scaffold with metal prosthesis,
osteoinduction

**[Device Trade Name]{.underline}**: InFUSE™ Bone Graft/LT-CAGE™ Lumbar
Tapered Fusion Device

**[Applicant's Name and Address]{.underline}**: Medtronic Sofamor Danek,
Inc. USA

> 1800 Pyramid Place

Memphis, TN 38132

**[Premarket Approval Application]{.underline}**

**[(PMA) Number:]{.underline}** P000058

**[Date of Panel Recommendation]{.underline}**: January 10, 2002

**[Date of Notice of Approval of Application]{.underline}:** July 2,
2002

# 

# II. INDICATIONS FOR USE

The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device is
indicated for spinal fusion procedures in skeletally mature patients
with degenerative disc disease (DDD) at one level from L~4~-S~1~. DDD is
defined as discogenic back pain with degeneration of the disc confirmed
by patient history and radiographic studies. These DDD patients may also
have up to Grade I spondylolisthesis at the involved level. Patients
receiving the InFUSE™ Bone Graft/ LT-CAGE™ Lumbar Tapered Fusion Device
should have had at least six months of nonoperative treatment prior to
treatment with the InFUSE™ Bone Graft/LT-CAGE™ device. The InFUSE™ Bone
Graft/ LT-CAGE™ Lumbar Tapered Fusion Device is to be implanted via an
anterior open or an anterior laparoscopic approach.

# III. CONTRAINDICATIONS

-   The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device is
    contraindicated for patients with a known hypersensitivity to
    recombinant human Bone Morphogenetic Protein-2, bovine Type I
    collagen or to other components of the formulation.

-   The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device should
    not be used in the vicinity of a resected or extant tumor.

-   InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device should not
    be used in patients who are skeletally immature (\<18 years of age
    or no radiographic evidence of epiphyseal closure).

-   The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device should
    not be used in pregnant women. The potential effects of rhBMP-2 on
    the human fetus have not been evaluated.

-   The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device should
    not be implanted in patients with an active infection at the
    operative site or with an allergy to titanium or titanium alloy.

#  {#section-3 .Style1}

#  {#section-4 .Style1}

# IV. WARNINGS AND PRECAUTIONS {#iv.-warnings-and-precautions .Style1}

**[WARNINGS:]{.underline}**

-   Women of childbearing potential should be advised that antibody
    formation to rhBMP-2 or its influence on fetal development have not
    been assessed. In the clinical trial supporting the safety and
    effectiveness of the InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered
    Fusion Device, 2/277 (0.7%) patients treated with InFUSE™ Bone Graft
    component and 1/127 (0.8%) patients treated with autograft bone
    developed antibodies to rhBMP-2. The effect of maternal antibodies
    to rhBMP-2, as might be present for several months following device
    implantation, on the unborn fetus is unknown. Additionally, it is
    unknown whether fetal expression of BMP-2 could re-expose mothers
    who were previously antibody positive, thereby eliciting a more
    powerful immune response to BMP-2 with adverse consequences for the
    fetus. Studies in genetically altered mice indicate that BMP-2 is
    critical to fetal development and that lack of BMP-2 activity, as
    might be induced by antibody formation, may cause neonatal death or
    birth defects.

-   The safety and effectiveness of the InFUSE™ Bone Graft/LT-CAGE™
    Lumbar Tapered Fusion Device in nursing mothers has not been
    established. It is not known if BMP-2 is excreted in human milk.

-   Women of childbearing potential should be advised to not become
    pregnant for one year following treatment with the InFUSE™ Bone
    Graft/LT-CAGE™ Lumbar Tapered Fusion Device.

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-   The safety and effectiveness of the InFUSE Bone Graft component with
    other spinal implants, implanted at locations other than the lower
    lumbar spine, or used in surgical techniques other than anterior
    open or anterior laparoscopic approaches have not been established.
    When degenerative disc disease was treated by a posterior lumber
    interbody fusion procedure with cylindrical threaded cages,
    posterior bone formation was observed in some instances.

-   The implantation of the InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered
    Fusion Device using an anterior laparoscopic surgical approach is
    associated with a higher incidence of retrograde ejaculation when
    compared to implantation using the an anterior open surgical
    approach.

**[PRECAUTIONS:]{.underline}**

# 

# General

-   The safety and effectiveness of repeat applications of the InFUSE™
    Bone Graft component has not been established.

-   The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device should
    only be used by surgeons who are experienced in spinal fusion
    procedures and have undergone adequate training with this device,
    for anterior laparoscopic and/or anterior open procedures.

-   Two LT-CAGE™ Lumbar Tapered Fusion Device components should be
    implanted side by side at the surgical level whenever possible.

-   The LT-CAGE™ Lumbar Tapered Fusion Device components and instruments
    must be sterilized prior to use according to the sterilization
    instructions provided in the package insert for that component,
    unless supplied sterile and clearly labeled as such.

-   The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device is
    intended for single use only. Discard unused product and use a new
    device for subsequent applications.

-   Prior to use, inspect the packaging, vials and stoppers for visible
    damage. If damage is visible, do not use the product. Retain the
    packaging and vials and contact a Medtronic Sofamor Danek
    representative.

-   Do not use after the printed expiration date on the label.

    **Hepatic and Renal Impairment**

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-   The safety and effectiveness of the InFUSE™ Bone Graft/LT-CAGE™
    Lumbar Tapered Fusion Device in patients with hepatic or renal
    impairment has not been established. Pharmacokinetic studies of
    rhBMP-2 indicate that the renal and hepatic systems are involved
    with its clearance.

**Geriatrics**

-   Clinical studies of the InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered
    Fusion Device did not include sufficient numbers of patients 65
    years and older to determine whether they respond differently from
    younger subjects.

# Bone formation {#bone-formation .Style1}

-   The safety and effectiveness of the InFUSE™ Bone Graft/LT-CAGE™
    Lumbar Tapered Fusion Device has not been demonstrated in patients
    with metabolic bone diseases.

-   While not specifically observed in the clinical study, the potential
    for ectopic, heterotopic or undesirable exuberant bone formation
    exists.

##### **Antibody Formation/Allergic Reactions**

-   The safety and effectiveness of the InFUSE™ Bone Graft/LT-CAGE™
    Lumbar Tapered Fusion Device has not been demonstrated in patients
    with autoimmune disease.

-   The safety and effectiveness of the InFUSE™ Bone Graft/LT-CAGE™
    Lumbar Tapered Fusion Device has not been demonstrated in patients
    with immunosuppressive disease or suppressed immune systems
    resulting from radiation therapy, chemotherapy, steroid therapy or
    other treatments.

### 

### Immunogenicity

-   As with all therapeutic proteins, there is a potential for immune
    responses to be generated to the InFUSE™ Bone Graft component. The
    immune response to the InFUSE™ Bone Graft components was evaluated
    in 349 investigational patients and 183 control patients receiving
    lumbar interbody fusions.

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-   *Anti-rhBMP-2 antibodies:* 2/349 (0.6%) patients receiving the
    InFUSE™ Bone Graft component developed antibodies vs. 1/183 (0.5%)
    in the control group.

-   *Anti-bovine Type I collagen antibodies:* 18.1% of patients
    receiving the InFUSE™ Bone Graft component developed antibodies to
    bovine Type I collagen vs. 14.2% of control patients. No patients in
    either group developed anti-human Type I collagen antibodies.

-   The presence of antibodies to rhBMP-2 was not associated with immune
    mediated adverse events such as allergic reactions. The neutralizing
    capacity of antibodies to rhBMP-2 is not known.

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-   The incidence of antibody detection is highly dependent on the
    sensitivity and specificity of the assay. Additionally, the
    incidence of antibody detection may be influenced by several factors
    including sample handling, concomitant medications and underlying
    disease. For these reasons, comparison of the incidence of
    antibodies to the InFUSE™ Bone Graft component with the incidence of
    antibodies to other products may be misleading.

# 

# V. DEVICE DESCRIPTION

The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device consists of
two components containing three parts-- a tapered metallic spinal fusion
cage, a recombinant human bone morphogenetic protein and a
carrier/scaffold for the bone morphogenetic protein and resulting bone.
The InFUSE™ Bone Graft component is inserted into the LT-CAGE™ Lumbar
Tapered Fusion Device component to form the complete InFUSE™ Bone
Graft/LT-CAGE™ Lumbar Tapered Fusion Device. These components must be
used as a system. The InFUSE™ Bone Graft component must not be used
without the LT-CAGE™ Lumbar Tapered Fusion Device component.

**LT-CAGE™ Lumbar Tapered Fusion Device component**

The LT-CAGE™ device consists of a hollow, perforated, machined cylinder
with opposing flat sides. The cage has a tapered design with an angle of
8.8° and is available in diameters ranging from 14mm to 18mm at the
narrow end of the taper, 17mm to 22 mm at the wide end of the taper and
in lengths ranging from 20mm to 26mm. There are two holes on each of the
two flat sides. On each of the two rounded aspects, there is a single
rounded slot. The implants have a helical screw thread on the outer
surface. One end of the device is closed. The other end is open to be
filled with the InFUSE™ Bone Graft component.

The LT-CAGE™ implants are made from implant grade titanium alloy
(Ti-6Al-4V) described by such standards as ASTM F136 or its ISO
equivalent.

The LT-CAGE™ Lumbar Tapered Fusion Device component is sold separately
from the InFUSE™ Bone Graft component, however, these two components
must be used together. The package labeling for the LT-CAGE™ Lumbar
Tapered Fusion Device contains complete product information for this
component.

InFUSE™ Bone Graft component

InFUSE™ Bone Graft consists of recombinant human Bone Morphogenetic
Protein-2 (rhBMP-2, known as dibotermin alfa) placed on an absorbable
collagen sponge (ACS). The InFUSE™ Bone Graft component induces new bone
tissue at the site of implantation. Based on data from non-clinical
studies, the bone formation process develops from the outside of the
implant towards the center until the entire InFUSE™ Bone Graft component
is replaced by trabecular bone.

rhBMP-2 is the active agent in the InFUSE™ Bone Graft component. rhBMP-2
is a disulfide-linked dimeric protein molecule with two major subunit
species of 114 and 131 amino acids. Each subunit is glycosylated at one
site with high-mannose-type glycans. rhBMP-2 is produced by a
genetically engineered Chinese hamster ovary cell line.

rhBMP-2 and excipients are lyophilized. Upon reconstitution, each
milliliter of rhBMP-2 solution contains: 1.5 mg of rhBMP-2; 5.0 mg
sucrose, NF; 25 mg glycine, USP; 3.7 mg L-glutamic acid, FCC; 0.1 mg
sodium chloride, USP; 0.1 mg polysorbate 80, NF; and 1.0 mL of sterile
water. The reconstituted rhBMP-2 solution has a pH of 4.5, and is clear,
colorless and essentially free from plainly visible particulate matter.

The ACS is a soft, white, pliable, absorbent implantable matrix for
rhBMP-2. ACS is made from bovine Type I collagen obtained from deep
flexor (Achilles) tendon. The ACS acts as a carrier for the rhBMP-2 and
acts as a scaffold for new bone formation.

Three sizes of the InFUSE™ Bone Graft component are available based on
the internal volume of the LT-CAGE™ Lumbar Tapered Fusion Device
component that is selected. The table below lists the appropriate
InFUSE™ Bone Graft kit for the corresponding LT-CAGE™ Lumbar Tapered
Fusion Device component size:

+---------+------------+----------+---------------+------------------+
| **      |            |          |               |                  |
| InFUSE™ |            |          |               |                  |
| Bone    |            |          |               |                  |
| Graft/L |            |          |               |                  |
| T-CAGE™ |            |          |               |                  |
| Lumbar  |            |          |               |                  |
| Tapered |            |          |               |                  |
| Fusion  |            |          |               |                  |
| Device  |            |          |               |                  |
| Combina |            |          |               |                  |
| tions** |            |          |               |                  |
+---------+------------+----------+---------------+------------------+
| L       |            | App      |               |                  |
| T-CAGE™ |            | ropriate |               |                  |
| Lumbar  |            | InFUSE™  |               |                  |
| Tapered |            | Bone     |               |                  |
| Fusion  |            | Graft    |               |                  |
| Device  |            | Kit      |               |                  |
+---------+------------+----------+---------------+------------------+
| Part \# | Size       | Part \#  | Kit name      | Reconstituted    |
|         |            |          | (size in cc)  | rhBMP-2/ACS      |
|         | (lead      |          |               | graft volume     |
|         | diameter,  |          |               |                  |
|         | mm x       |          |               |                  |
|         | length,    |          |               |                  |
|         | mm)        |          |               |                  |
+---------+------------+----------+---------------+------------------+
| 8941420 | 14x20      | 7510200  | Small (2.8)   | 2.8ml            |
+---------+------------+----------+---------------+------------------+
| 8941423 | 14x23      | 7510200  | Small (2.8)   | 2.8ml            |
+---------+------------+----------+---------------+------------------+
| 8941620 | 16x20      | 7510200  | Small (2.8)   | 2.8ml            |
+---------+------------+----------+---------------+------------------+
| 8941623 | 16x23      | 7510400  | Medium (5.6)  | 5.6ml            |
+---------+------------+----------+---------------+------------------+
| 8941626 | 16x26      | 7510400  | Medium (5.6)  | 5.6ml            |
+---------+------------+----------+---------------+------------------+
| 8941823 | 18x23      | 7510400  | Medium (5.6)  | 5.6ml            |
+---------+------------+----------+---------------+------------------+
| 8941826 | 18x26      | 7510600  | Large Pre-Cut | 8.0ml            |
|         |            |          | (8.0)         |                  |
+---------+------------+----------+---------------+------------------+
| 8941826 | 18x26      | 7510800  | Large II (    | 8.0ml            |
|         |            |          | 8.0)          |                  |
+---------+------------+----------+---------------+------------------+

Each kit contains all the components necessary to prepare the InFUSE™
Bone Graft component: the rhBMP-2 which must be reconstituted, sterile
water, absorbable collagen sponges, syringes with needles, this package
insert and instructions for preparation. The number of each item may
vary depending on the size of the kit.

The rhBMP-2 is provided as a lyophilized powder in vials delivering
either 4.2 mg or 12 mg of protein. After appropriate reconstitution,
both configurations result in the same formulation and concentration
(1.5 mg/mL) of rhBMP-2. The solution is then applied to the provided
absorbable collagen sponge(s). The InFUSE™ Bone Graft component is
prepared at the time of surgery and allowed a prescribed amount of time
(no less than 15 minutes) before placement inside of the LT-CAGE™ Lumbar
Tapered Fusion Device components. The Instructions for Preparation
contain complete details on preparation of the InFUSE™ Bone
Graft/LT-CAGE™ Lumbar Tapered Fusion Device.

No other warranties, express or implied, are made. Implied warranties of
merchantability and fitness for a particular purpose or use are
specifically excluded.

**VI. ALTERNATIVE PRACTICES AND PROCEDURES**

Non-surgical alternatives to performing interbody fusion with the
InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device include, but
are not limited to, watchful waiting with no intervention, physical
therapy, medications, external bracing, chiropractic care, spinal
injections, bed rest and exercising.

Surgical alternatives include posterior lumbar interbody fusion (PLIF)
procedures with or without instrumentation, anterior lumbar interbody
fusion (ALIF) procedures with or without instrumentation, combined
anterior and posterolateral (360°) fusion procedures, fusions using
anterior/anterolateral spinal systems (e.g., plate and screw systems) or
fusions using posterior spinal systems (e.g., pedicle screw/rod and
hook/rod systems). In each case the fusions would involve the use of
autograft and/or allograft bone.

# VII. MARKETING HISTORY

The InFUSE™ Bone Graft components, manufactured by Genetics Institute,
Inc., has only been used in IDE studies in the United States.

The LT-CAGE™ Lumbar Tapered Fusion Device component, manufactured by
Medtronic Sofamor Danek, has been distributed in the United States since
September, 1999 and it has not been withdrawn from marketing for any
reason. Since 1995, this device component has been distributed outside
of the United States and it has not been withdrawn from marketing for
any reason.

The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device has not
been marketed for the combined use described in the PMA in the United
States or any foreign country.

**VIII. POTENTIAL ADVERSE EFFECTS OF THE DEVICE ON HEALTH**

The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device was
implanted in 288 investigational patients and compared to 139 control
patients who received an LT-CAGE™ Lumbar Tapered Fusion Device filled
with iliac crest autograft. The investigational patients were implanted
with the device via either an open anterior surgical approach or a
laparoscopic anterior surgical approach. The control patients were
implanted only via the open anterior surgical approach.

Adverse event rates presented are based on the number of patients having
at least one occurrence for a particular adverse event divided by the
total number of patients in that treatment group.

[]{.mark}

[]{.mark}

<table style="width:100%;">
<colgroup>
<col style="width: 14%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 4%" />
<col style="width: 5%" />
<col style="width: 4%" />
<col style="width: 9%" />
<col style="width: 7%" />
</colgroup>
<thead>
<tr class="header">
<th colspan="17"><p><strong>ADVERSE EVENTS</strong></p>
<p>(InFUSE™ Bone Graft/LT-Cage™ Device data combined from all experience
with the device)</p></th>
</tr>
<tr class="odd">
<th></th>
<th colspan="2"><strong>Surgery</strong></th>
<th colspan="2"><p><strong>Postoperative</strong></p>
<p><strong>(1 day - &lt;4 Weeks)</strong></p></th>
<th colspan="2"><p><strong>6 Weeks</strong></p>
<p><strong>(≥4 Wks - &lt;9 Weeks)</strong></p></th>
<th colspan="2"><p><strong>3 Months</strong></p>
<p><strong>(≥9 Wks - &lt;5 Months)</strong></p></th>
<th colspan="2"><p><strong>6 Months</strong></p>
<p><strong>(≥5 Mos- &lt;9 Months)</strong></p></th>
<th colspan="2"><p><strong>12 Months</strong></p>
<p><strong>(≥9 Mos- &lt;19 Months)</strong></p></th>
<th colspan="2"><p><strong>24 Months</strong></p>
<p><strong>(≥19 Mos- &lt;30 Months)</strong></p></th>
<th colspan="2"><p><strong># of Patients Reporting &amp;</strong></p>
<p><strong>Total adverse events</strong></p></th>
</tr>
<tr class="header">
<th><strong>Complication</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><strong>Inves.</strong></th>
<th><strong>Control</strong></th>
<th><p><strong>Investigational</strong></p>
<p><strong># (% of 288)</strong></p>
<p><strong>total events</strong></p></th>
<th><p><strong>Control</strong></p>
<p><strong>#(% of 139)</strong></p>
<p><strong>total events</strong></p></th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>Anatomical/Technical Difficulty</td>
<td>10</td>
<td>3</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>10 (3.5)</p>
<p>10</p></td>
<td><p>3 (2.2)</p>
<p>3</p></td>
</tr>
<tr class="even">
<td>Back and/or Leg Pain</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>4</td>
<td>11</td>
<td>5</td>
<td>10</td>
<td>5</td>
<td>14</td>
<td>4</td>
<td>20</td>
<td>7</td>
<td>6</td>
<td>8</td>
<td><p>65 (22.6)</p>
<p>72</p></td>
<td><p>30 (21.6)</p>
<p>33</p></td>
</tr>
<tr class="odd">
<td>Cancer</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>1 (0.3)</p>
<p>1</p></td>
<td><p>1 (0.7)</p>
<p>1</p></td>
</tr>
<tr class="even">
<td>Cardio/Vascular</td>
<td>2</td>
<td>0</td>
<td>4</td>
<td>5</td>
<td>6</td>
<td>2</td>
<td>1</td>
<td>3</td>
<td>2</td>
<td>1</td>
<td>3</td>
<td>2</td>
<td>0</td>
<td>1</td>
<td><p>15 (5.2)</p>
<p>18</p></td>
<td><p>12 (8.6)</p>
<p>14</p></td>
</tr>
<tr class="odd">
<td>Death</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>0 (0.0)</p>
<p>0</p></td>
<td><p>1 (0.7)</p>
<p>1</p></td>
</tr>
<tr class="even">
<td>Dural Injury</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>0 (0.0)</p>
<p>0</p></td>
<td><p>1 (0.7)</p>
<p>1</p></td>
</tr>
<tr class="odd">
<td>Gastrointestinal</td>
<td>1</td>
<td>0</td>
<td>38</td>
<td>22</td>
<td>2</td>
<td>0</td>
<td>5</td>
<td>1</td>
<td>7</td>
<td>1</td>
<td>9</td>
<td>3</td>
<td>4</td>
<td>5</td>
<td><p>53 (18.4)</p>
<p>67</p></td>
<td><p>27 (19.4)</p>
<p>32</p></td>
</tr>
<tr class="even">
<td>Graft Site Related</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>8</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>0 (0.0)</p>
<p>0</p></td>
<td><p>8 (5.8)</p>
<p>8</p></td>
</tr>
<tr class="odd">
<td><p>Implant Displacement/</p>
<p>Loosening</p></td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>1</td>
<td>3</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>5 (1.7)</p>
<p>5</p></td>
<td><p>1 (0.7)</p>
<p>1</p></td>
</tr>
<tr class="even">
<td>Infection</td>
<td>0</td>
<td>0</td>
<td>19</td>
<td>9</td>
<td>8</td>
<td>4</td>
<td>4</td>
<td>1</td>
<td>5</td>
<td>1</td>
<td>3</td>
<td>0</td>
<td>0</td>
<td>2</td>
<td><p>35 (12.2)</p>
<p>39</p></td>
<td><p>16 (11.5)</p>
<p>17</p></td>
</tr>
<tr class="odd">
<td>Malpositioned Implant</td>
<td>5</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>5 (1.7)</p>
<p>5</p></td>
<td><p>0 (0.0)</p>
<p>0</p></td>
</tr>
<tr class="even">
<td>Neurological</td>
<td>0</td>
<td>0</td>
<td>7</td>
<td>5</td>
<td>7</td>
<td>3</td>
<td>5</td>
<td>2</td>
<td>5</td>
<td>2</td>
<td>10</td>
<td>3</td>
<td>5</td>
<td>7</td>
<td><p>36 (12.5)</p>
<p>39</p></td>
<td><p>21 (15.1)</p>
<p>22</p></td>
</tr>
<tr class="odd">
<td>Non-Union</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>1</td>
<td>3</td>
<td>2</td>
<td>0</td>
<td>1</td>
<td>1</td>
<td><p>5 (1.7)</p>
<p>5</p></td>
<td><p>4 (2.9)</p>
<p>4</p></td>
</tr>
<tr class="even">
<td>Other</td>
<td>6</td>
<td>6</td>
<td>17</td>
<td>11</td>
<td>7</td>
<td>2</td>
<td>3</td>
<td>4</td>
<td>8</td>
<td>4</td>
<td>14</td>
<td>8</td>
<td>9</td>
<td>8</td>
<td><p>50 (17.4)</p>
<p>64</p></td>
<td><p>37 (26.6)</p>
<p>43</p></td>
</tr>
<tr class="odd">
<td>Other Pain</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>1</td>
<td>2</td>
<td>0</td>
<td>4</td>
<td>2</td>
<td>5</td>
<td>1</td>
<td>7</td>
<td>6</td>
<td>6</td>
<td>3</td>
<td><p>21 (7.3)</p>
<p>25</p></td>
<td><p>12 (8.6)</p>
<p>13</p></td>
</tr>
<tr class="even">
<td>Respiratory</td>
<td>0</td>
<td>0</td>
<td>3</td>
<td>2</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>1</td>
<td><p>5 (1.7)</p>
<p>5</p></td>
<td><p>4 (2.9)</p>
<p>4</p></td>
</tr>
<tr class="odd">
<td>Retrograde Ejaculation</td>
<td>0</td>
<td>0</td>
<td>4</td>
<td>1</td>
<td>5</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>2</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>11 (7.9)<a href="#fn1" class="footnote-ref" id="fnref1"
role="doc-noteref"><sup>1</sup></a></p>
<p>12</p></td>
<td><p>1 (1.4)<a href="#fn2" class="footnote-ref" id="fnref2"
role="doc-noteref"><sup>2</sup></a></p>
<p>1</p></td>
</tr>
<tr class="even">
<td>Spinal Event</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>2</td>
<td>0</td>
<td>0</td>
<td>6</td>
<td>2</td>
<td>8</td>
<td>3</td>
<td>8</td>
<td>8</td>
<td>4</td>
<td>2</td>
<td><p>24 (8.3)</p>
<p>27</p></td>
<td><p>16 (11.5)</p>
<p>17</p></td>
</tr>
<tr class="odd">
<td>Subsidence</td>
<td>0</td>
<td>0</td>
<td>3</td>
<td>2</td>
<td>2</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>7 (2.4)</p>
<p>7</p></td>
<td><p>2 (1.4)</p>
<p>2</p></td>
</tr>
<tr class="even">
<td>Trauma</td>
<td>0</td>
<td>0</td>
<td>4</td>
<td>4</td>
<td>5</td>
<td>3</td>
<td>11</td>
<td>6</td>
<td>14</td>
<td>5</td>
<td>27</td>
<td>9</td>
<td>11</td>
<td>7</td>
<td><p>60 (20.8)</p>
<p>72</p></td>
<td><p>29 (20.9)</p>
<p>34</p></td>
</tr>
<tr class="odd">
<td>Urogenital</td>
<td>1</td>
<td>0</td>
<td>20</td>
<td>5</td>
<td>2</td>
<td>0</td>
<td>2</td>
<td>2</td>
<td>6</td>
<td>1</td>
<td>2</td>
<td>1</td>
<td>4</td>
<td>2</td>
<td><p>33 (11.5)</p>
<p>37</p></td>
<td><p>10 (7.2)</p>
<p>11</p></td>
</tr>
<tr class="even">
<td>Vascular Intra-Op</td>
<td>15</td>
<td>5</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>14 (4.9)</p>
<p>15</p></td>
<td><p>5 (3.6)</p>
<p>5</p></td>
</tr>
<tr class="odd">
<td>Vertebral Fracture</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td><p>1 (0.3)</p>
<p>1</p></td>
<td><p>0 (0.0)</p>
<p>0</p></td>
</tr>
<tr class="even">
<td>Any Adverse Event</td>
<td colspan="14"></td>
<td>213 (74.0)</td>
<td>112 (80.6)</td>
</tr>
</tbody>
</table>
<aside id="footnotes" class="footnotes footnotes-end-of-document"
role="doc-endnotes">
<hr />
<ol>
<li id="fn1"><p>Percent of 140 males.<a href="#fnref1"
class="footnote-back" role="doc-backlink">↩︎</a></p></li>
<li id="fn2"><p>Percent of 70 males.<a href="#fnref2"
class="footnote-back" role="doc-backlink">↩︎</a></p></li>
</ol>
</aside>

The reported rates of several adverse events were high, but similar, in
both the investigational and control groups. These events included back
and leg pain, neurological events, gastrointestinal events, spinal
events, cardiovascular events and infection.

The rate of graft site related events was 8% in the control group and
not applicable in the investigational groups.

Some of the reported adverse events required surgical interventions
subsequent to the initial surgery. The number of subjects requiring a
second surgical intervention was 10.4% (30/288) in the investigational
groups and 13.7% (19/139) in the control group. The majority of
supplemental fixations were due to painful nonunion.

Urogenital events occurred with greater frequency in the investigational
groups (11.5%) compared to the control group (7%). Retrograde
ejaculation rates were greater in the investigational groups (11
subjects) compared to the control group (1 subject) with the majority of
events occurring in the early postoperative period.

The incidence of adverse events that were considered device related,
including implant displacement/loosening, implant malposition and
subsidence were all greater in the investigational groups compared to
the control group. The rates of these events were low, however, and may
be partially attributed to a learning curve associated with the
laparoscopic surgical approach. The rate of nonunion requiring secondary
surgery in the investigational groups was comparable to that of the
control group. One death was reported - a control group subject with
cardiovascular disease.

**[Potential Adverse Events:]{.underline}**

The following is a list of potential adverse events which may occur with
spinal fusion surgery with the InFUSE™ Bone Graft/LT-CAGE™ Lumbar
Tapered Fusion Device. Some of these adverse events may have been
previously reported in the adverse events table.

-   Bone fracture.

-   Bowel or bladder problems.

-   Cessation of any potential growth of the operated portion of the
    spine. Loss of spinal mobility or function.

-   Change in mental status.

-   Damage to blood vessels and cardiovascular system compromise.

-   Damage to internal organs and connective tissue.

-   Death.

-   Development of respiratory problems.

-   Disassembly, bending, breakage, loosening, and/or migration of
    components.

-   Dural tears.

-   Ectopic and/or exuberant bone formation.

-   Fetal development complications.

-   Foreign body (allergic) reaction.

-   Gastrointestinal complications.

-   Incisional complications.

-   Infection.

-   Insufflation complications.

-   Neurological system compromise.

-   Nonunion (or pseudarthrosis), delayed union, mal-union.

-   Postoperative change in spinal curvature, loss of correction,
    height, and/or reduction.

-   Retrograde ejaculation.

-   Scar formation.

-   Tissue or nerve damage.

> **Note:** Additional surgery may be necessary to correct some of these
> potential adverse events.

# IX. SUMMARY OF NONCLINICAL LABORATORY STUDIES 

Three sets of nonclinical laboratory studies were preformed -- those
related to the LT-CAGE™ Lumbar Tapered Fusion Device component alone,
those related to the InFUSE™ Bone Graft component alone, *i.e.*,
rhBMP-2/ACS, and those related to the complete device, *i.e.*, the
InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device.

**IX.1 Characterization of the LT-CAGE™ Lumbar Tapered Fusion Device
Component**

The LT-CAGE™ Lumbar Tapered Fusion Device component was originally
approved for use in the treatment of degenerative disc disease in the
lumbar spine in P970015/S10. That PMA supplement, as well as the
preclinical module for the current PMA, contained a description of the
design characteristics and mechanical performance of this device
component compared to that of the previously-approved parallel-sided
spinal fusion cage (referred to as the INTER FIX Threaded Fusion
Device). These data are summarized below.

# IX.1.1 Design characteristics 

The following table summarizes the design characteristics between a
previously-approved design of the fusion cage component (the INTER FIX
Threaded Fusion Device) and the version of the device utilized in the
current combination device:

+------------------+-------------------------------+-------------------+
| **               | **INTER FIX**                | **LT-CAGE**      |
| Characteristic** |                               |                   |
+------------------+-------------------------------+-------------------+
| Material         | Ti-6Al-4V alloy (ASTM F-136   | same              |
|                  | or ISO equivalent)            |                   |
+------------------+-------------------------------+-------------------+
| Shape            | cylindrical (parallel sides)  | tapered           |
+------------------+-------------------------------+-------------------+
| Outer diameter   | 12 - 20                       | distal end: 14 -- |
| (mm)             |                               | 18                |
|                  |                               |                   |
|                  |                               | proximal end: 18  |
|                  |                               | --22              |
+------------------+-------------------------------+-------------------+
| Length (mm)      | 20 -- 29                      | 20 -- 26          |
+------------------+-------------------------------+-------------------+
| Restored         | 5                             | 8                 |
| lordosis angle   |                               |                   |
| (°)              |                               |                   |
+------------------+-------------------------------+-------------------+
| Surface porosity | 40 -- 45                      | 38 -- 50          |
| (%)              |                               |                   |
+------------------+-------------------------------+-------------------+
| Hole to metal    | 35                            | 33                |
| ratio (%)        |                               |                   |
+------------------+-------------------------------+-------------------+

**IX.1.2 Mechanical Testing**

The sponsor performed a number of mechanical tests to compare the
mechanical behavior of the LT-CAGE™ Lumbar Tapered Fusion Device
component to that of a previously-approved fusion cage design and, where
appropriate, to the expected *in vivo* loads. These tests were performed
under both static and dynamic conditions and were conducted in
accordance with appropriate mechanical testing standards, *e.g.*, ASTM.
The sponsor also performed tests which evaluated the impact of the
LT-CAGE™ Lumbar Tapered Fusion Device component on the intrinsic
stiffness of cadaveric spines. These results (averages) are summarized
below:

+--------------------------+-------------+-------------+-------------+
| **Test**                 | *           | **INTER     | **Max. *in  |
|                          | *LT-CAGE** | FIX**      | vivo*       |
|                          |             |             | load**      |
+--------------------------+-------------+-------------+-------------+
| Static axial compression | 47,646      | 79,797      | 4000 --     |
| yield strength (N)       |             |             | 13,000      |
+--------------------------+-------------+-------------+-------------+
| Dynamic axial            | at least    | at least    | 2000 --     |
| compression load at      | 9600        | 9600        | 3000        |
| runout (5x10^6^ cycles)  |             |             |             |
| (N)                      |             |             |             |
+--------------------------+-------------+-------------+-------------+
| Dynamic multi-axial      | 95          | 113         | 33          |
| compression load at      |             |             |             |
| runout (5x10^6^ cycles)  |             |             |             |
| (N-m)                    |             |             |             |
+--------------------------+-------------+-------------+-------------+
| Static shear strength    | 37,728      | 30,572      | 3200        |
| (N)                      |             |             |             |
+--------------------------+-------------+-------------+-------------+
| Dynamic shear strength   | at least    | 4000        | 1400        |
| (N)                      | 5600        |             |             |
+--------------------------+-------------+-------------+-------------+
| Insertion torque (N-m)   | 0.95        | 0.87        | \-          |
+--------------------------+-------------+-------------+-------------+
| Pushout load (N)         | 711         | 697         | \-          |
+--------------------------+-------------+-------------+-------------+
| Construct stiffness in   | Flexion -   | Flexion -   | \-          |
| calf spines              | 122.90      | 71.17       |             |
|                          |             |             |             |
| (% of intact spine)      | Extension - | Extension - |             |
|                          | 127.24      | 119.34      |             |
+--------------------------+-------------+-------------+-------------+

**IX.2 Characterization of the InFUSE™ Bone Graft Component**

The safety of rhBMP-2/ACS has been evaluated in an extensive series of
toxicology studies of both the rhBMP-2 growth factor alone and the
rhBMP-2 growth factor in combination with the ACS carrier/scaffold.

# In the following sections, the text describes the general results from a class of studies, while the accompanying tables identify specific studies and their outcome. {#in-the-following-sections-the-text-describes-the-general-results-from-a-class-of-studies-while-the-accompanying-tables-identify-specific-studies-and-their-outcome. .Style1}

#  {#section-8 .Style1}

# IX.2.1 Biocompatibility Studies {#ix.2.1-biocompatibility-studies .Style1}

The safety of rhBMP-2/ACS was evaluated in a series of biocompatibility
tests. Under the conditions of these studies, there was no mortality or
evidence of significant systemic toxicity in the mouse, no
intracutaneous toxicity or significant dermal irritation in the rabbit,
no evidence of delayed dermal contact sensitization in the guinea pig,
no evidence of cell lysis or toxicity in the extract and overlay
cytotoxicity tests, no evidence of hemolysis, and no evidence of
cellular mutagenicity. In the rabbit muscle irritation study,
macroscopic evaluation of rhBMP-2/ACS revealed a hard, granular
formation around the test site. The implant was graded macroscopically
as a slight irritant relative to the negative control. Microscopically,
the implant was graded as a nonirritant. The implant site revealed the
presence of new bone formation consistent with the known pharmacologic
action of rhBMP-2.

+------------------+-----------+---------+----------------------------+
| **Study Type:**  | **        | Route   | **Relevant Findings**      |
|                  | Groups/** |         |                            |
| **Species**      |           |         |                            |
|                  | **No.     |         |                            |
|                  | A         |         |                            |
|                  | nimals/** |         |                            |
|                  |           |         |                            |
|                  | **Sex**   |         |                            |
+==================+===========+=========+============================+
| Intracutaneous   | 1/2       | IC      | The test article extracts  |
| toxicity:        |           |         | showed no evidence of      |
| rabbit: New      |           |         | causing significant        |
| Zealand white    |           |         | irritation or toxicity.    |
+------------------+-----------+---------+----------------------------+
| Delayed contact  | 2/15/F    | ID      | The test article extracts  |
| sensitization:   |           |         | showed no evidence of      |
| Guinea pig       |           | skin    | causing sensitization.     |
|                  |           | patch   |                            |
+------------------+-----------+---------+----------------------------+
| Cytoxicity/ *in  | n/a       | n/a     | The test article extracts  |
| vitro*: WI-38    |           |         | showed no evidence of      |
| Human embryonic  |           |         | causing cell lysis or      |
| cell line        |           |         | toxicity.                  |
+------------------+-----------+---------+----------------------------+
| Cytoxicity/ *in  | n/a       | n/a     | The test article extracts  |
| vitro* agarose   |           |         | showed no evidence of      |
| overlay: L-929   |           |         | causing cell lysis or      |
| mouse fibroblast |           |         | toxicity.                  |
| cell line        |           |         |                            |
+------------------+-----------+---------+----------------------------+
| Systemic         | n/a       | IV      | The test article extracts  |
| toxicity         |           |         | were not considered        |
| study/mouse      |           | IP      | systemically toxic to the  |
|                  |           |         | mouse at the prescribed    |
|                  |           |         | USP dosage.                |
+------------------+-----------+---------+----------------------------+
| *In vitro*       | n/a       | n/a     | The test article extracts  |
| hemolysis:       |           |         | were not considered        |
| rabbit whole     |           |         | hemolytic.                 |
| blood            |           |         |                            |
+------------------+-----------+---------+----------------------------+
| Surgical muscle  | n/a       | IM      | The test articles were     |
| implantation     |           |         | considered to be           |
| study: rabbit/   |           |         | trace-to-mild irritants    |
|                  |           |         | after implantation in      |
|                  |           |         | muscle.                    |
+------------------+-----------+---------+----------------------------+
| Ames *in vitro*  | n/a       | n/a     | The test article extracts  |
| mutagenicity     |           |         | were not considered        |
| study            |           |         | mutagenic.                 |
+------------------+-----------+---------+----------------------------+

> n/a = not applicable

## IX.2.1.2 Safety of rhBMP-2 Administered Intravenously: Acute and repeated dose, 28-Day Toxicity Studies

rhBMP-2 protein was studied in single- and multiple-dose general
toxicology studies in the rat and beagle dog with up to 28 days of daily
dosing. rhBMP-2 was administered intravenously (IV), at a range of doses
that varied from slightly lower to substantially higher than the total
doses (weight based) of rhBMP-2 that have been used in human clinical
trials. There were no treatment-related toxicities observed in these
studies. For example, although rhBMP-2 has potent bone-inducing activity
at the local site of administration, systemic administration of
suprapharmacologic doses of rhBMP-2 did not result in disseminated bone
formation at any remote site, in any study.

+-----------------+-----------+-----------+----------------------------+
| **Study Type:** | **        | **        | **Relevant Findings**      |
|                 | Groups/** | rhBMP-2** |                            |
| **Species/      |           |           |                            |
| Strain**        | No.       | **        |                            |
|                 | Animals/  | (mg/kg)** |                            |
|                 |           |           |                            |
|                 | Sex       |           |                            |
+=================+===========+===========+============================+
| Acute toxicity: | 5/        | saline    | No toxicity observed.      |
|                 |           |           |                            |
| Rat/            | 5/sex     | vehicle   | No-toxic-effect dose was   |
|                 |           |           | 0.533 mg/kg IV.            |
| Sprague-        | sacrifice | 0.053     |                            |
|                 |           |           |                            |
| Dawley with     |           | 0.160     |                            |
| sacrifices on   |           |           |                            |
| Days 2, 7 and   |           | 0.533     |                            |
| 15              |           |           |                            |
+-----------------+-----------+-----------+----------------------------+
| Acute toxicity: | 4/        | vehicle   | No treatment-related       |
|                 |           |           | findings in animals        |
| Rat/            | 5/sex     | 0.53      | sacrificed at Day 2.       |
|                 |           |           |                            |
| Sprague-        | sacrifice | 1.6       | Slight-to-mild             |
|                 |           |           | dose-related               |
| Dawley with     |           | 5.3       | chondrogenesis at          |
| sacrifices on   |           |           | injection sites.           |
| Days 2 and 15   |           |           |                            |
|                 |           |           | No-toxic-effect dose was   |
|                 |           |           | 5.3 mg/kg IV.              |
+-----------------+-----------+-----------+----------------------------+
| Acute toxicity: | 4/        | vehicle   | No toxicity observed.      |
|                 |           |           |                            |
| Dog/            | 1/sex     | 0.53      | No-toxic-effect dose was   |
|                 |           |           | 5.3 mg/kg IV.              |
| Beagle          |           | 1.6       |                            |
|                 |           |           |                            |
| Sacrifice on    |           | 5.3       |                            |
| Day 15          |           |           |                            |
+-----------------+-----------+-----------+----------------------------+
| 28-Day          | 5/        | saline    | Ten deaths unrelated to    |
| toxicity:       |           |           | treatment (vehicle, 0.016, |
|                 | 10/(      | vehicle   | 0.05, 0.16)                |
| Rat/            | 5)^a^/sex |           |                            |
|                 |           | 0.016     | Dose-related soft tissue   |
| Sprague-        |           |           | thickening and cartilage   |
|                 |           | 0.05      | formation in subcutaneous  |
| Dawley          |           |           | tissue at injection sites. |
|                 |           | 0.16      | Following 28-day recovery  |
|                 |           |           | period, the soft tissue    |
|                 |           |           | thickening regressed and   |
|                 |           |           | matured to bone.           |
|                 |           |           | No-toxic-effect dose was   |
|                 |           |           | 0.16 mg/kg/day IV.         |
+-----------------+-----------+-----------+----------------------------+
| 28-Day          | 5         | saline    | Dose-related perivascular  |
| toxicity:       |           |           | fibroplasia at injection   |
|                 | 3/(2) ^a^ | vehicle   | site in all                |
| Dog/            | /sex      |           | rhBMP-2-treated animals    |
|                 |           | 0.016     | with bone formation in     |
| Beagle          |           |           | mid- to high-dose groups.  |
|                 |           | 0.05      |                            |
|                 |           |           | No-toxic-effect dose was   |
|                 |           | 0.16      | 0.16 mg/kg/day IV.         |
+-----------------+-----------+-----------+----------------------------+
| ^a^ () numbers  |           |           |                            |
| of additional   |           |           |                            |
| recovery        |           |           |                            |
| sub-group       |           |           |                            |
| animals in      |           |           |                            |
| control and     |           |           |                            |
| high-dose       |           |           |                            |
| groups          |           |           |                            |
+-----------------+-----------+-----------+----------------------------+

### IX.2.1.3 Chronic Toxicity

The long-term safety of implanted rhBMP-2/ACS was evaluated in two
studies, a 6-month mandibular/maxillofacial inlay study in beagle dogs
and a 1-year femoral onlay study in Sprague-Dawley rats. These studies
were designed to assess the potential long-term systemic and local
effects of rhBMP-2/ACS in two species at two skeletal sites. Implants of
rhBMP-2/ACS had no systemic effects and local effects were associated
with the osteoinductive activity of rhBMP-2. Transient, low-titer immune
responses were observed in the dog study.

+-----------+--------------+-------------+----------------------------+
| **Study   | **Groups/**  | **rhBMP-2** | **Relevant Findings**      |
| Type:**   |              |             |                            |
|           | **No.        | **(mg/kg)** |                            |
| *         | Animals/**   |             |                            |
| *Species/ |              |             |                            |
| Strain**  | Sex          |             |                            |
+===========+==============+=============+============================+
| 6-month   | 5            | sham        | No effects of treatment on |
| Ma        |              | surgery,    | clinical signs,            |
| ndibular/ | 2/sex        | v           | hematology, or clinical    |
| Maxi      |              | ehicle/ACS, | chemistry. Dose-related    |
| llofacial | sacrificed   |             | post-surgical swelling. As |
| Implant   | at 3 and 6   | 0.078 mg/kg | swelling subsided (3-4     |
| (at inlay | months       |             | weeks), firm masses near   |
| defect    | post-        | (0.4        | the zygomatic and          |
| site):    | implantation | mg/mL)/ACS, | mandibular implant sites   |
| D         |              |             | were detected in most      |
| og/Beagle |              | 0.312 mg/kg | rhBMP-2-treated animals.   |
|           |              |             | Histologically, the        |
|           |              | (1.6        | rhBMP-2-treated implant    |
|           |              | mg/mL)/ACS, | sites were composed of     |
|           |              |             | abundant fibrocellular     |
|           |              | 0.781       | tissue and/or new bone     |
|           |              | mg/kg,      | formation within and       |
|           |              |             | around the defect site.    |
|           |              | (4.0        | There were fluid filled    |
|           |              | mg/mL)/ACS  | tissue cysts and           |
|           |              |             | occasionally strands of    |
|           |              |             | residual ACS material at   |
|           |              |             | implant sites with         |
|           |              |             | apparent regression        |
|           |              |             | between 3 and 6 months.    |
|           |              |             | Implant site changes were  |
|           |              |             | expected exaggerated       |
|           |              |             | pharmacologic responses to |
|           |              |             | rhBMP-2/ACS and were not   |
|           |              |             | toxicologically            |
|           |              |             | significant.               |
|           |              |             | No-toxic-effect dose was   |
|           |              |             | 0.781 mg/kg (4.0 mg/mL     |
|           |              |             | concentration rhBMP-2).    |
|           |              |             | Transient low titer        |
|           |              |             | antibody responses were    |
|           |              |             | observed in 15/24 (62.5%)  |
|           |              |             | of the treated animals.    |
+-----------+--------------+-------------+----------------------------+
| 1-year    | 5            | v           | Slight increased incidence |
| Femoral   |              | ehicle/ACS, | and severity of surgical   |
| onlay     | 10/sex       |             | site swelling at 1.6       |
| Implant   |              | 0.04 mg/kg  | mg/kg. Dose-related        |
| To        | sacrificed   |             | pharmacologic effect of    |
| xicology: | at 1, 6, and | (0.1        | increased incidence and/or |
| Rat/Sprag | 12 months    | mg/mL)/     | severity of bone formation |
| ue-Dawley | post-        | ACS,        | at implant site in all     |
|           | implantation |             | rhBMP-2/ACS treatment      |
|           |              | 0.3 mg/kg   | groups. No toxicity at any |
|           |              |             | dose.                      |
|           |              | (0.75       |                            |
|           |              | mg/mL)/     |                            |
|           |              | ACS,        |                            |
|           |              |             |                            |
|           |              | 1.6 mg/kg   |                            |
|           |              |             |                            |
|           |              | (4.0        |                            |
|           |              | mg/mL)/ ACS |                            |
+-----------+--------------+-------------+----------------------------+

**IX.2.1.4 Safety of rhBMP-2 Administered Intravenously: Fertility,
General Reproductive Performance and Teratology**

Because BMP-2 participates in embryological development, rhBMP-2 was
evaluated for any effect on reproduction or fetal development. Studies
evaluated rhBMP-2 at total doses (weight based) that ranged from
slightly lower to substantially higher than rhBMP-2 doses that are
anticipated in clinical use (up to approximately 1 mg rhBMP-2/kg, total
delivered dose). The effects of rhBMP-2 on the reproduction and
fertility of male and female Sprague-Dawley rats was studied. Maternal
and paternal mating performance and reproductive parameters were not
affected by treatment. Range-finding studies followed by developmental
toxicity studies were conducted in both Sprague-Dawley rats and New
Zealand white rabbits. There was no evidence of maternal toxicity,
embryolethality, fetotoxicity, or teratogenicity.

+-----------------+-----------+-----------+----------------------------+
| **Study Type:** | Groups/   | **        | **Relevant Findings**      |
|                 |           | rhBMP-2** |                            |
| **Species/      | No.       |           |                            |
| Strain**        | Animals/  | **        |                            |
|                 |           | (mg/kg)** |                            |
|                 | Sex       |           |                            |
+=================+===========+===========+============================+
| Fertility:      | 5/        | saline    | Maternal and paternal      |
|                 |           |           | mating performance and     |
| rat             | 40/F      | vehicle   | reproductive parameters    |
| /Sprague-Dawley |           |           | were not affected by       |
|                 | 40/M      | 0.016     | treatment. No-toxic-effect |
|                 |           |           | dose was 0.16 mg/kg/day    |
|                 |           | 0.05      | IV.                        |
|                 |           |           |                            |
|                 |           | 0.16      |                            |
+-----------------+-----------+-----------+----------------------------+
| Range-finding   | 7/        | saline    | No maternal toxicity,      |
| Teratology:     |           |           | embryolethality, or gross  |
|                 | 5/F       | vehicle   | fetal abnormalities.       |
| rabbit/         |           |           | No-toxic-effect level was  |
|                 |           | 0.016     | 1.6 mg/kg/day IV.          |
| New Zealand     |           |           |                            |
| white rabbit    |           | 0.05      |                            |
|                 |           |           |                            |
|                 |           | 0.16      |                            |
|                 |           |           |                            |
|                 |           | 0.5       |                            |
|                 |           |           |                            |
|                 |           | 1.6       |                            |
|                 |           |           |                            |
|                 |           | Days 6 to |                            |
|                 |           | 18        |                            |
|                 |           | gestation |                            |
+-----------------+-----------+-----------+----------------------------+
| Teratology:     | 5/        | saline    | No maternal toxicity,      |
| rabbit/New      |           |           | embryolethality, or gross  |
| Zealand white   | 20/F      | vehicle   | fetal abnormalities.       |
|                 |           |           | No-toxic-effect level was  |
|                 |           | 0.016     | 1.6 mg/kg/day IV.          |
|                 |           |           | Definitive teratology      |
|                 |           | 0.5       | study in rats. The         |
|                 |           |           | incidences of              |
|                 |           | 1.6       | malformations were not     |
|                 |           |           | significantly different    |
|                 |           | Days 6 to | between control and        |
|                 |           | 18        | treated groups.            |
|                 |           | gestation |                            |
+-----------------+-----------+-----------+----------------------------+
| Range-finding   | 7/        | saline    | No maternal toxicity,      |
| Teratology:     |           |           | embryolethality, or gross  |
|                 | 6/F       | vehicle   | fetal abnormalities.       |
| Rat/            |           |           | No-toxic-effect level was  |
|                 |           | 0.016     | 1.6 mg/kg/day IV.          |
| Sprague-Dawley  |           |           |                            |
|                 |           | 0.05      |                            |
|                 |           |           |                            |
|                 |           | 0.16      |                            |
|                 |           |           |                            |
|                 |           | 0.5       |                            |
|                 |           |           |                            |
|                 |           | 1.6       |                            |
|                 |           |           |                            |
|                 |           | Days 6 to |                            |
|                 |           | 17        |                            |
|                 |           | gestation |                            |
+-----------------+-----------+-----------+----------------------------+
| Teratology:     | 5/        | saline    | No maternal toxicity,      |
| Rat/            |           |           | embryolethality or fetal   |
|                 | 25/F      | vehicle   | abnormalities.             |
| Sprague-Dawley  |           |           | No-toxic-effect dose was   |
|                 |           | 0.16      | 1.6 mg/kg/day IV. The      |
|                 |           |           | definitive teratology      |
|                 |           | 0.5       | study in rats was          |
|                 |           |           | repeated. In the initial   |
|                 |           | 1.6       | study there was a          |
|                 |           |           | nonsignificant difference  |
|                 |           | Days 6 to | in skeletal formation      |
|                 |           | 17        | between the rhBMP-2 groups |
|                 |           | gestation | and the saline and control |
|                 |           |           | groups. Examination of     |
|                 |           |           | skeletal variance revealed |
|                 |           |           | a significant reduction in |
|                 |           |           | sternebral variance in all |
|                 |           |           | treated groups.            |
+-----------------+-----------+-----------+----------------------------+
| Repeat          | 2/        | vehicle   | It was hypothesized that   |
| teratology:     |           |           | the difference in skeletal |
|                 | 25/F      | 1.6       | formation in the preceding |
| rat             |           |           | study was a result of the  |
| /Sprague-Dawley |           | Days 6 to | time of cesarean section   |
|                 |           | 17        | rather than a treatment    |
|                 |           |           | effect. This repeat study  |
|                 |           | gestation | had a random order of      |
|                 |           |           | selection for time of      |
|                 |           |           | cesarean section. No       |
|                 |           |           | maternal toxicity,         |
|                 |           |           | embryolethality,           |
|                 |           |           | fetotoxicity or            |
|                 |           |           | teratogenicity and no      |
|                 |           |           | difference in skeletal     |
|                 |           |           | formation between the      |
|                 |           |           | control and rhBMP-2        |
|                 |           |           | groups. No-toxic-effect    |
|                 |           |           | level was 1.6 mg/kg/day    |
|                 |           |           | IV.                        |
+-----------------+-----------+-----------+----------------------------+

## IX.2.1.5 Carcinogenicity/Genotoxicity

In addition to the Ames Mutagenicity assay, the sponsor investigated the
potential for rhBMP-2 to stimulate the proliferation of primary tumor
cell isolates and tumor cell lines. rhBMP-2 was examined for growth
potentiating activity *in vitro* on human tumor cell lines and primary
tumor cell isolates at concentrations of 10 to 1000 ng/mL. No growth
potentiating activity was observed. rhBMP-2 exhibited growth inhibition
of several carcinoma-derived tumors. The studies did not include
analyses to determine if the cells expressed BMP type I and II
receptors. Overall, studies investigating the potential effects of
rhBMP-2 on tumor cell growth showed minimal evidence of growth
potentiation including studies of osteosarcoma cell lines.

+--------------+-----------+----------+--------------------------------+
| **Study      | Groups/   | *        | **Relevant Findings**          |
| Type:**      |           | *rhBMP-2 |                                |
|              | No.       | (mg/kg)  |                                |
| **Species/   | Animals/  | /Route** |                                |
| Strain**     |           |          |                                |
|              | Sex       |          |                                |
+==============+===========+==========+================================+
| Growth       | n/a       | 10, 100, | No tumor cell growth           |
| potential on |           | and 1000 | stimulation. Significant       |
| primary      |           | ng/mL    | inhibition of colony forming   |
| tumor        |           | conce    | units in 16 of 65 specimens at |
| isolates *in |           | ntration | 1000 ng/kg                     |
| vitro* (Soda |           | *in      |                                |
| et al.,      |           | vitro*   |                                |
| *Anti-Cancer |           |          |                                |
| Drugs*,      |           |          |                                |
| 1998)        |           |          |                                |
+--------------+-----------+----------+--------------------------------+
| Inhibition   | n/a       | 10, 100, | No effect on osteosarcoma cell |
| of tumor     |           | and 1000 | line growth. Inhibitory        |
| growth *in   |           | ng/mL    | effects on several soft tissue |
| vitro* with  |           | conce    | carcinoma cell lines.          |
| human tumor  |           | ntration |                                |
| cell lines   |           | *in      |                                |
|              |           | vitro*   |                                |
+--------------+-----------+----------+--------------------------------+

# IX.2.2 Immunology {#ix.2.2-immunology .Style1}

Formation of antibodies to rhBMP-2 and Type I collagen in canines,
rhesus monkeys and rats was monitored using Enzyme Linked Immusorbent
Assays (ELISAs). In general, rhBMP-2 or bovine Type I collagen was
coated onto microtiter plates. Controls or serum samples were diluted in
assay buffer and incubated on the plates. Enzyme-conjugated reagents
were used to detect bound antibodies. Enzyme substrates were then
incubated on the plates and optical densities of the solutions were
measured in order to quantitate the presence of anti-rhMBP-2 or Type I
collagen antibodies. Immune responses to rhBMP-2 were observed in
nonhuman primates and in dogs. Please refer to the 6 month beagle dog
study in section IX.2.1.3, Chronic Toxicity, and the radius, critical
size defect repair/nonhuman primate study in section IX.2.5, Animal
Studies.

#### IX.2.3 Pharmacokinetics

##### **IX.2.3.1 rhBMP-2 Protein Administered Intravenously**

Although rhBMP-2 is intended to be delivered with the ACS as two part
device component, pharmacokinetic results obtained from IV dosing
provide a means to evaluate the extent and duration of systemic exposure
of rhBMP-2. Studies were conducted to characterize the pharmacokinetics
of rhBMP-2 in the blood of rats and monkeys. The uptake of rhBMP-2 by
highly perfused tissues and organs is rapid, but the residence of the
protein is short. Catabolism of the protein is extensive and renal
excretion of trichloroacetic acid-soluble radioactivity is rapid.
rhBMP-2 is rapidly eliminated in rat and nonhuman primates (t~½~ = 16
minutes in the rat and t~½~ = 6.7 minutes in nonhuman primates) from the
systemic circulation following intravenous administration. A study
conducted in juvenile and adult Sprague-Dawley rats revealed that
juvenile rats, like adult rats, cleared rhBMP-2 rapidly. Results also
showed a lower maximal concentration, higher clearance and a larger
initial volume of distribution for rhBMP-2 in juvenile rats as compared
to adult rats. As a result of these pharmacokinetic characteristics,
systemic presence of rhBMP-2 in the circulation is minimal after IV
dosing.

+--------------+----------+----------+---------------------------------+
| ########     | **G      | *        | **Relevant Findings**           |
|  Study Type/ | roups/** | *rhBMP-2 |                                 |
|              |          | Dose**   |                                 |
| **Species/   | **No.    |          |                                 |
| Strain**     | Animals  |          |                                 |
|              | (per     |          |                                 |
|              | group)** |          |                                 |
+==============+==========+==========+=================================+
| PK single    | 4/3      | 0.43     | Clearance of ^125^I-rhBMP-2 was |
| dose:        |          |          | rapid and biexponential:        |
|              |          | 4.3      | T~1/2α~^a^ = 0.8 min, and       |
| rat/Sp       |          |          | T~1/2β~^b^ =15.3 min. Most of   |
| rague-Dawley |          | 43       | the administered dose (92%) was |
|              |          |          | recovered by 24 hours in the    |
|              |          | 860      | urine as TCA-soluble counts per |
|              |          | μg/kg    | minute.                         |
|              |          |          |                                 |
|              |          |          | > ^a^ T~1/2α~ = half-life of    |
|              |          |          | > initial phase                 |
|              |          |          | >                               |
|              |          |          | > ^b^ T~1/2β~ = half-life of    |
|              |          |          | > terminal phase                |
+--------------+----------+----------+---------------------------------+
| PK single    | 2/3      | 4.9      | Clearance of ^125^I-rhBMP-2 was |
| dose:        |          | μg/kg    | rapid and biexponential:        |
|              |          |          | T~1/2α~^a^ = 1.0 min, and       |
| nonhuman     |          |          | T~1/2β~^b^ =7.0 min.            |
| primate/     |          |          |                                 |
|              |          |          |                                 |
| cynomolgus   |          |          |                                 |
| monkey       |          |          |                                 |
+--------------+----------+----------+---------------------------------+
| Biod         | 8/3      | 4.3      | Rapid localization to liver     |
| istribution: |          | μg/kg    | with metabolism and excretion   |
| rat/Sp       |          |          | into urine. Biphasic            |
| rague-Dawley |          |          | disposition was observed with   |
|              |          |          | initial and terminal half-life  |
|              |          |          | of 0.8 and 31 minutes,          |
|              |          |          | respectively.                   |
+--------------+----------+----------+---------------------------------+
| Biod         | 8/3      | 7.1      | ^125^I-rhBMP-2 rapidly          |
| istribution: |          | μg/kg    | distributed to the highly       |
|              |          |          | perfused tissues; 1 minute      |
| rat/Sp       |          |          | after dosing, 82.4% of the dose |
| rague-Dawley |          |          | was recovered in the liver,     |
|              |          |          | lung, kidney, and spleen. The   |
|              |          |          | liver was the predominant site  |
|              |          |          | of ^125^I-rhBMP-2 localization  |
|              |          |          | throughout the study.           |
+--------------+----------+----------+---------------------------------+
| PK single    | 2/12-24  | 3.0      | Clearance of ^131^I-rhBMP-2 was |
| dose:        |          | mg/kg    | rapid and biexponential in both |
| juvenile and |          |          | juvenile and adult rats as      |
| adult        |          |          | assessed by serum acid          |
| rats/Sp      |          |          | precipitable radioactivity and  |
| rague-Dawley |          |          | by ELISA.                       |
+--------------+----------+----------+---------------------------------+

### IX.2.3.2 Local Retention of rhBMP‑2 Administered With ACS

The local residence time of rhBMP‑2 when applied to the ACS was assessed
following subcutaneous (SC) implantation in rats and implantation at
orthotopic sites in rats and rabbits. The results from all three models
were similar. In the rat femoral onlay model, ^125^I-rhBMP‑2 was slowly
released from the implant site with a mean residence time of
approximately 8 days (refer to Figure below). The peak amount of
radiolabeled rhBMP‑2 detected in the blood was small, 0.1% of the
implanted dose, and consistent with the rapid systemic clearance
described above.

> Retention of rhBMP‑2 Following Implantation of rhBMP‑2/ACS (left) and
> Pharmacokinetic Evaluation Following Intravenous Administration of
> rhBMP‑2 (right) in the Rat

![](media/image1.wmf){width="2.795275590551181in"
height="1.839763779527559in"}![](media/image2.wmf){width="2.825196850393701in"
height="1.8326771653543308in"}

### IX.2.3.3 Interactions Between rhBMP-2 and the Absorbable Collagen Sponge

The importance of retaining rhBMP‑2 at the implant site for optimal bone
formation was highlighted in one study in which the heparin-binding
domain of rhBMP‑2 was removed using plasmin. Following implantation with
ACS, this modified protein was found to leave the implant site much more
rapidly than the native protein; for example, only 18% of the
plasmin-cleaved material was present at 3 hours, contrasting with 56%
for the native protein. Though the plasmin-cleaved protein was highly
active in a cell culture assay, bone formation *in vivo* was
substantially reduced, indicating that retention of bioactive material
at the implant site is critical for the desired osteogenic activity.

As the local retention of rhBMP‑2 is important for localized bone
formation, several studies evaluated the effect of potential variables
on retention following SC implantation in the rat or orthotopic
implantation in the rabbit. The relative retention of rhBMP‑2 was
unaffected by the concentration of rhBMP‑2 administered (between 0.8 and
2.0 mg/mL) or the formulation buffer. The amount of rhBMP‑2 incorporated
into ACS (a measure of the binding of rhBMP‑2 to the sponge prior to
implantation) had a minimal effect on rhBMP‑2 retention *in vivo*, and
no effect on the rate of release of rhBMP‑2 into serum *in vitro*. These
results suggest that the release of rhBMP‑2 *in vivo* is independent of
the binding of rhBMP‑2 to the sponge *in vitro*, and may be
diffusion-controlled.

> **IX.2.4 Effect of Nicotine and Glucocorticosteroids on Implantation
> with rhBMP-2/ACS**

In animal studies, the sponsor has shown that rhBMP-2/ACS induces bone
and fracture repair in the presence of several agents which compromise
bone metabolism, for example, nicotine and corticosteroids.

+-----------------+-----------+-----------+----------------------------+
| **Study Type/** | **        | **        | **Relevant Findings**      |
|                 | Groups/** | rhBMP-2** |                            |
| **Species**     |           |           |                            |
|                 | **No.     | **        |                            |
|                 | Animals** | (mg/mL)** |                            |
+=================+===========+===========+============================+
| Subcutaneous    | 8^a^/4-5  | 0         | Systemic nicotine          |
| implant/rat     |           |           | treatment did not inhibit  |
|                 |           | 0.01      | the ability of rhBMP-2/ACS |
|                 |           |           | to induce bone formation.  |
|                 |           | 0.1       |                            |
|                 |           |           |                            |
|                 |           | 0.4       |                            |
+-----------------+-----------+-----------+----------------------------+
| Ulnar osteotomy | 3         | 0.2       | Nicotine did not affect    |
| repair/rabbit   | ^b^/12-13 |           | the rate of fracture       |
|                 |           |           | repair in this model.      |
+-----------------+-----------+-----------+----------------------------+
| Subcutaneous    | 8^c^/6    | 0         | Prednisolone treatment     |
| implant/rat     |           |           | dramatically inhibited     |
|                 |           | 0.01      | bone growth and body mass  |
|                 |           |           | gain. Prednisolone         |
|                 |           | 0.1       | treatment also inhibited   |
|                 |           |           | ectopic bone formation;    |
|                 |           | 0.4       | however, the high dose of  |
|                 |           |           | rhBMP-2/ACS overcame this  |
|                 |           |           | inhibition.                |
+-----------------+-----------+-----------+----------------------------+
| Ulnar osteotomy | 4^d^/12   | 0         | Prednisolone treatment     |
| repair/rabbit   |           |           | inhibited fracture         |
|                 |           | 0.2       | healing. Treatment with    |
|                 |           |           | rhBMP-2/ACS overcame this  |
|                 |           |           | inhibition and enhanced    |
|                 |           |           | healing in both the        |
|                 |           |           | control and prednisolone   |
|                 |           |           | treated animals.           |
+-----------------+-----------+-----------+----------------------------+

> ^a^ four nicotine-treated; four control
>
> ^b^ nicotine-treated; nicotine pre-treated, or control
>
> ^c^ four prednisolone-treated; four control
>
> ^d^ prednisolone-treated or control; two sacrifice timepoints

## IX.2.5 Animal Studies

Pharmacology studies have demonstrated that rhBMP-2/ACS can induce bone
and repair large, segmental critical-sized defects in rat femora, rabbit
radii and ulnae, dog radii, and nonhuman primate radii. The induced bone
biologically and structurally integrates with the pre-existing bone, and
remodels physiologically, *i.e.*, consistent with the biomechanical
forces placed on it. In addition, the rhBMP-2/ACS-induced bone can
repair itself following fracture, in a manner indistinguishable from
native bone. Separate studies demonstrated that rhBMP-2/ACS can
accelerate healing in rabbit and goat long bone fracture models. Thus,
radiographic, biomechanical, and histologic evaluation of the induced
bone indicates that it is appropriate for the anatomic site where it
forms, and functions biologically and biomechanically as native bone.

Histologic analyses from many pharmacology studies have characterized
the cellular events involved in the bone induction process initiated by
rhBMP-2/ACS. Mesenchymal cells from the surrounding tissues first
infiltrate the periphery of the rhBMP-2/ACS implant. As the ACS is
degraded, these cells appear to differentiate and begin to form
trabecular bone and/or cartilage. Vascular invasion is evident at the
same time. The bone formation process temporally extends from the
periphery of the rhBMP-2/ACS implant towards the center, until the
entire rhBMP-2/ACS implant is replaced by trabecular bone. Remodeling of
the trabecular bone then occurs depending on the physiologic form of the
site and function applied to the bone. This ability of rhBMP-2/ACS to
support bone remodeling may also be responsible in part for the biologic
and biomechanical integration of the new bone induced by rhBMP-2/ACS
with that of the surrounding bone.

+-----------------+-----------+-----------+----------------------------+
| #####           | **G       | **        | **Relevant Findings**      |
| ### Study Type/ | roups/No. | rhBMP-2** |                            |
|                 | Animals   |           |                            |
| **Species**     | (per      | **        |                            |
|                 | group)**  | (mg/mL)** |                            |
+=================+===========+===========+============================+
| Subcutaneous    | 5/6       | 0         | Substantial bone induction |
| implant/rat     |           |           | was observed in all        |
|                 |           | 0.17      | implants containing        |
|                 |           |           | rhBMP-2.                   |
|                 |           | 0.33      |                            |
|                 |           |           |                            |
|                 |           | 0.66      |                            |
|                 |           |           |                            |
|                 |           | 1.7       |                            |
+-----------------+-----------+-----------+----------------------------+
| Femur critical  | 6/7       | 0.013     | Dose-response-related      |
|                 |           |           | healing of critical-sized  |
| sized defect    |           | 0.025     | bone defects measured by   |
|                 |           |           | radiologic and histologic  |
| repair/rat      |           | 0.05      | criteria. Therapeutic dose |
|                 |           |           | (concentration) range of   |
|                 |           | 0.1       | 0.025 -- 0.05 mg/mL        |
|                 |           |           |                            |
|                 |           | 0.2       | rhBMP-2/ACS delineated for |
|                 |           |           | this model.                |
|                 |           | 0.4       |                            |
+-----------------+-----------+-----------+----------------------------+
| Radius          | 4/3       | 0         | All rhBMP-2/ACS-treated    |
| critical-sized  |           |           | animals healed at 12 weeks |
| defect          |           | 0.05      | by all criteria.           |
| repair/dog      |           |           | Dose-dependent generation  |
|                 |           | 0.2       | of excess bone and voids;  |
|                 |           |           | voids observed especially  |
|                 |           | 0.8       | in bone formed outside of  |
|                 |           |           | implant area.              |
|                 |           |           | Biomechanical values of    |
|                 |           |           | all rhBMP-2 dose groups    |
|                 |           |           | are equal or superior to   |
|                 |           |           | autologous bone-grafted    |
|                 |           |           | controls.                  |
+-----------------+-----------+-----------+----------------------------+
| Radius          | 3/5       | 0         | Functional loading of      |
| critical-size   |           |           | rhBMP-2/ACS-treated radii  |
| defect          |           | 0.05      | at 16 week demonstrated.   |
| repair/dog      |           |           | Remodeling and             |
|                 |           | 0.2       | consolidation of induced   |
|                 |           |           | bone observed during       |
|                 |           |           | subsequent 8-32 week.      |
|                 |           |           | Remodeling over time of    |
|                 |           |           | void spaces observed.      |
|                 |           |           | Stress fractures in        |
|                 |           |           | rhBMP-2/ACS and autogenous |
|                 |           |           | bone grafted limbs         |
|                 |           |           | occurred at similar        |
|                 |           |           | frequencies and healed at  |
|                 |           |           | similar rates.             |
+-----------------+-----------+-----------+----------------------------+
| Radius          | 9/2-6     | 0         | Variable bone induction    |
| critical-size   |           |           | observed in range of 0.4   |
| defect          |           | 0.05      | to 1.5 mg/ml rhBMP-2/ACS.  |
| repair/nonhuman |           |           | No dose-response defined.  |
| primate         |           | 0.2       | No radiolucent voids       |
|                 |           |           | generated at any dose.     |
|                 |           | 0.4       | Dose-related generation of |
|                 |           |           | antibodies to rhBMP-2 were |
|                 |           | 0.8       | observed in 35% (7/20)     |
|                 |           |           | treated. Antibodies to     |
|                 |           | 1.3       | Type I collage were        |
|                 |           |           | observed in 7% (1/14); no  |
|                 |           | 1.5       | correlation with efficacy. |
|                 |           |           |                            |
|                 |           | 1.9       |                            |
|                 |           |           |                            |
|                 |           | 3.1       |                            |
+-----------------+-----------+-----------+----------------------------+
| Ulnar           | 6^a^/1    | 0         | Bone induction within      |
| critical-size   |           |           | defect by 4 weeks.         |
| defect          |           | 0.75      | Accelerated removal of ACS |
| repair/nonhuman |           |           | in presence of rhBMP-2.    |
| primate         |           |           | Compression of ACS limited |
|                 |           |           | amount of bone induction   |
|                 |           |           | observed.                  |
+-----------------+-----------+-----------+----------------------------+
| Femoral head    | 3^a^/2    | 0         | Superior retention of      |
| core            |           |           | rhBMP-2, bone induction    |
| defect/sheep    |           | 0.4       | within defect and bone     |
|                 |           |           | formation surrounding      |
|                 |           | 1.5       | defect when implanted with |
|                 |           |           | ACS as compared to         |
|                 |           |           | injection in buffer.       |
|                 |           |           | rhBMP-2/ACS induced early  |
|                 |           |           | remodeling in trabecular   |
|                 |           |           | bone surrounding           |
|                 |           |           | implantation site.         |
+-----------------+-----------+-----------+----------------------------+
| Femoral head    | 2^b^/2    | 0         | Superior bone induction    |
| core            |           |           | observed in response to    |
| defect/sheep    |           | 0.8       | rhBMP-2/ACS compared to    |
|                 |           |           | ACS alone or surgical      |
|                 |           | 1.5       | control. Early bone        |
|                 |           |           | resorption surrounding     |
|                 |           |           | defect observed followed   |
|                 |           |           | by subsequent bone         |
|                 |           |           | formation. A positive      |
|                 |           |           | correlation was found      |
|                 |           |           | between retention of       |
|                 |           |           | rhBMP-2 at the implant     |
|                 |           |           | site and bone formation.   |
+-----------------+-----------+-----------+----------------------------+
| Ulnar osteotomy | many/5-15 | 0         | Increase in torsional      |
| repair/rabbit   |           |           | loading parameters with    |
|                 | 3^a^/10   | 0.05      | rhBMP-2/ACS placed as an   |
| Pilot I^b^      |           |           | onlay. rhBMP-2/ACS-treated |
|                 | 2^c^/15   | 0.1       | limbs healed at 3-4 weeks, |
| Pilot II^b^     |           |           | as compared to 6 weeks in  |
|                 | 6/15      | 0.2       | controls.                  |
| Main            |           |           |                            |
|                 |           | 0.4       |                            |
|                 |           |           |                            |
|                 |           | 0.8       |                            |
+-----------------+-----------+-----------+----------------------------+
| Ulnar osteotomy | 2/6^d^    | 0         | Torsional biomechanics in  |
|                 |           |           | the rhBMP-2/ACS group      |
| repair/rabbit   |           | 0.2       | 80-100% greater than       |
|                 |           |           | surgical control and ACS   |
|                 |           |           | groups at 3 and 4 weeks.   |
|                 |           |           | No difference between      |
|                 |           |           | surgical and ACS onlay     |
|                 |           |           | groups at any time point.  |
|                 |           |           | Approximately 25% decrease |
|                 |           |           | in time to bony union with |
|                 |           |           | rhBMP-2/ACS.               |
+-----------------+-----------+-----------+----------------------------+
| Tibial fracture | 2/1-2     | 0.2       | No obvious differences in  |
| repair/goat     |           |           | treated and control        |
|                 |           | 0.8       | fractures. Conclusions     |
|                 |           |           | difficult to reach due to  |
|                 |           |           | small sample size and lack |
|                 |           |           | of carrier control groups. |
+-----------------+-----------+-----------+----------------------------+
| Tibial fracture | 2/4       | 0         | rhBMP-2/ACS used as an     |
| repair/goat     |           |           | onlay resulted in          |
|                 |           | 0.4       | increased callus size and  |
|                 |           |           | maturity, as assessed      |
|                 |           |           | radiographically and       |
|                 |           |           | histologically. Fractures  |
|                 |           |           | wrapped with rhBMP-2/ACS   |
|                 |           |           | had increased torsional    |
|                 |           |           | toughness.                 |
+-----------------+-----------+-----------+----------------------------+
| Femoral         | 3/7       | 0         | Augmentation of the        |
| allograft       |           |           | allograft-host bone        |
| in              |           | 0.4       | junctions with rhBMP-2/ACS |
| corporation/dog |           |           | resulted in a stronger and |
|                 |           |           | more complete union than   |
|                 |           |           | with autogenous bone graft |
|                 |           |           | or ACS alone.              |
+-----------------+-----------+-----------+----------------------------+
| Radius defect   | 4/8       | 0         | No deleterious effects on  |
| repair/rabbit   |           |           | radiocarpal joint observed |
|                 |           | 0.1       | when rhBMP-2/ACS placed in |
|                 |           |           | a distal radius defect     |
|                 |           | 0.4       | connected to joint cavity. |
|                 |           |           |                            |
|                 |           | 1.3       |                            |
+-----------------+-----------+-----------+----------------------------+
| Mid-diaphyseal  | 4^e^/6    | 0.4       | Histologically there was   |
|                 |           |           | no treatment effect on     |
| Ulnar Osteotomy |           |           | morphology of the growth   |
|                 |           |           | plates.                    |
| repair/rabbit   |           |           |                            |
+-----------------+-----------+-----------+----------------------------+
| Ulnar osteotomy | 7^f^/3-9  | 0.2       | As assessed by radiography |
| repair/rabbit   |           |           | and histology, defects in  |
|                 |           |           | bone induced by            |
|                 |           |           | rhBMP-2/ACS heal by a      |
|                 |           |           | process similar to that    |
|                 |           |           | seen in normal bone.       |
+-----------------+-----------+-----------+----------------------------+

^a^ sacrifice at three timepoints

^b^ contralateral control = ACS or not treatment

^c^ sacrifice at two timepoints

^d^ at each of four timepoints

^e^ two or three month old rabbits; rhBMP-2/ACS or surgical control

^f^ seven timepoints

IX.2.6 Preclinical Effectiveness Evaluations Conclusions

Many of the animal pharmacology studies have included dose-ranging, and
from these results, a broad therapeutic concentration range, measured as
quantity of rhBMP-2 per unit volume of ACS, has been determined. This
therapeutic range is bordered on one side by inadequate bone formation
and on the other by excessive bone formation combined with an increased
incidence and size of fluid-filled void spaces within the induced bone
(both of which remodeled appropriately over time). The therapeutic
rhBMP-2 concentration range shifts with the animal species tested in
apparent accord with the bone formation rate of that animal. Thus,
higher concentrations are required in dogs than in rats, and even higher
concentrations in nonhuman primates. The upper end of the therapeutic
concentration range in nonhuman primates has not been defined by these
studies. The nonhuman primate therapeutic range, 0.4 -- 1.5 mg/mL
rhBMP-2, is the same that has been tested in humans. Both the
concentration of rhBMP-2 and the length of time that rhBMP-2 is present
at the implant site are positively correlated with the rate of bone
formation, the amount of bone formed, and the density of the resulting
bone.

In summary, the safety (toxicology and pharmacokinetics) and
bone-forming capacity of rhBMP-2/ACS have been extensively investigated
and are well understood. The nonclinical safety of systemically
delivered rhBMP-2 and locally delivered rhBMP-2/ACS has been extensively
studied and no toxicities have been identified in these studies. The
disposition of rhBMP-2 and rhBMP-2/ACS is characterized by slow release
of rhBMP-2 from the implantation site and rapid systemic clearance. This
profile results in minimal systemic exposure to rhBMP-2. Application of
rhBMP-2/ACS results in the induction of normal bone locally at the site
of implantation. This process includes the migration of mesenchymal
cells into the site, their proliferation and apparent differentiation
into bone-forming cells. The bone induced by rhBMP-2/ACS remodels and
assumes the structure appropriate to its location and function, as would
be expected from host bone.

**IX.2.7 Characterization of the InFUSE™ Bone Graft/LT-CAGE™ Lumbar
Tapered Fusion Device**

**IX.2.7.1 Preclinical Safety Studies**

The studies listed below were performed to ensure that the rhBMP-2/ACS
was safe for use in proximity to the spinal cord and to identify a dose
of rhBMP-2 sufficient to cause bone formation. The purpose of the first
study was to assess the effects of a rhBMP-2/ ACS combination on exposed
dura and neural tissue after standard decompressive lumbar laminectomy
using a canine model. This study represented a worst case situation in
which rhBMP-2/ACS or autogenous bone graft was in direct contact with
the spinal cord. The following three studies assessed rhBMP-2/ACS
induced fusion rates in monkeys and dogs.

+------------+-------------+------------+-----------------------------+
| **Study    | **Species   | **rhB      | **Relevant Findings**       |
| Type**     | (n/         | MP-2/ACS** |                             |
|            | group       |            |                             |
|            | )/Device(s) | **mg/site  |                             |
|            | tested**    | (mg/mL)**  |                             |
+============+=============+============+=============================+
| Im         | Dog/        | 0.24       | Clinical observation,       |
| plantation |             | (0.10)     | radiography, CT scans,      |
| on exposed | RhBMP-2/ACS |            | neurological exam,          |
| dura after |             |            | histology: No neurological  |
| l          |             |            | deficit, no spinal cord     |
| aminectomy |             |            | stenosis and no             |
|            |             |            | mineralization of the dura  |
|            |             |            | when rhBMP-2 placed         |
|            |             |            | directly on exposed dura.   |
|            |             |            | There was no difference     |
|            |             |            | between animals that        |
|            |             |            | received a dural nick and   |
|            |             |            | those that did not.         |
+------------+-------------+------------+-----------------------------+
| Lumbar:    | monkey (2)/ | 2 (0.43)   | Clinical evaluation,        |
| dosing     |             |            | radiography, CT scans,      |
| study      | 1\.         | 4 (0.85)   | histology: Highest dose had |
|            | rhBMP-2/ACS |            | equal fusion rate to        |
|            |             | 8 (1.70)   | autograft of 50%. The two   |
|            | 2\. rhBMP-2 |            | lower doses did not result  |
|            | Open        |            | in fusions.                 |
|            | Porosity    |            |                             |
|            | Polylactic  |            |                             |
|            | Acid Sponge |            |                             |
|            | (OPLA)      |            |                             |
|            |             |            |                             |
|            | 3\.         |            |                             |
|            | Autograft   |            |                             |
+------------+-------------+------------+-----------------------------+
| Lumbar:    | monkey (2)/ | 6 (0.43)   | Clinical evaluation,        |
| dosing     |             |            | radiography, CT scans,      |
| study      | rhBMP-2/ACS | 18 (1.29)  | histology: Significantly    |
|            |             |            | larger amounts of bone was  |
|            |             | 32 (2.27)  | formed in this study but    |
|            |             |            | inconsistently. Only 18 mg  |
|            |             |            | treated animals and one of  |
|            |             |            | 32 mg dose fused.           |
+------------+-------------+------------+-----------------------------+
| Lumbar:    | dog (2-4)/  | 0 (0)      | Clinical evaluation,        |
| dosing     |             |            | radiography, CT scans,      |
| study      | r           | 0.06       | histology, biomechanical    |
|            | hBMP-2/OPLA | (0.025)    | testing: All dogs treated   |
|            |             |            | with rhBMP-2 fused at 12    |
|            |             | 0.11       | weeks as assessed by        |
|            |             | (0.05)     | evaluation criteria. No     |
|            |             |            | statistical difference in   |
|            |             | 0.23       | fusion rate vs. dosage.     |
|            |             | (0.10)     |                             |
|            |             |            |                             |
|            |             | 0.46       |                             |
|            |             | (0.20)     |                             |
|            |             |            |                             |
|            |             | (0.92)     |                             |
|            |             |            |                             |
|            |             | (0.40)     |                             |
+------------+-------------+------------+-----------------------------+

**IX.2.7.2 Preclinical Efficacy Studies Directly Supportive of Lumbar
Spinal Fusion Intended Use**

The efficacy studies listed below are directly relevant to the intended
clinical indication and are presented as primary data for the
preclinical efficacy studies of rhBMP-2. These studies were performed to
investigate the effectiveness of rhBMP-2/ACS in promoting interbody
fusion of the lumbar spine. In three of these studies, the efficacy of
rhBMP-2/ACS was compared to that of autogenous bone graft. The fourth
study compared the ACS carrier alone to the ACS carrier with one of two
different doses of rhBMP-2.

+-------------+--------------+-------------+--------------------------+
| **Study     | **Species    | **rh        | **Relevant Findings**    |
| Type**      | (n/          | BMP-2/ACS** |                          |
|             | grou         |             |                          |
|             | p)/Device(s) | **mg/site   |                          |
|             | tested**     | (mg/mL)**   |                          |
+=============+==============+=============+==========================+
| Laproscopic | monkey       | 0 (0)       | Clinical evaluation,     |
| anterior    | (2-3)/       |             | radiography, CT scans,   |
| interbody   |              | 0.34 (0.75) | histology: All monkeys   |
| fusion      | rhBMP-2/     |             | treated with rhBMP-2     |
| using       | ACS/titanium | 0.68 (1.50) | fused by 24 weeks.       |
| titanium    | cage         |             | Neither of animals       |
| cage        |              |             | without rhBMP-2 fused.   |
+-------------+--------------+-------------+--------------------------+
| Anterior    | sheep (6)/   | 0.69 (0.43) | Clinical evaluation,     |
| interbody   |              |             | radiography, CT scans,   |
| using       | 1\.          |             | histology, biomechanical |
| titanium    | rhBMP-2/A    |             | testing: All sheep       |
| cage        | CS/allograft |             | treated with rhBMP-2     |
|             | bone dowel   |             | fused at 24 weeks as     |
|             | 2.           |             | assessed by histological |
|             | autogr       |             | evaluation. 37% of       |
|             | aft/titanium |             | autografts fused.        |
|             | cage         |             |                          |
+-------------+--------------+-------------+--------------------------+
| Anterior    | monkey (3)/  | 0.40 (1.50) | Clinical evaluation,     |
| interbody   |              |             | radiography, CT scans,   |
|             | 1\.          |             | histology: All monkeys   |
|             | rhBMP-2/A    |             | tested with rhBMP-2      |
|             | CS/allograft |             | fused by 24 weeks. 50%   |
|             |              |             | of autograft controls    |
|             | 2\.          |             | were fused at 24 weeks.  |
|             | Autograft    |             |                          |
|             | bone dowel   |             |                          |
+-------------+--------------+-------------+--------------------------+
| Lumbar      | sheep (6)/   | 0.43 (0.43) | Clinical evaluation,     |
| interbody   |              |             | radiography, histology:  |
|             | > 1\.        |             | 86% of rhBMP-2 treated   |
|             | > rhBMP-     |             | animals fused            |
|             | 2/ACS/Carbon |             | histologically vs. 83%   |
|             | > fiber      |             | of autograft controls.   |
|             | > reinforced |             | No difference in         |
|             | > polymer    |             | biomechanical testing.   |
|             | > device     |             |                          |
|             | >            |             |                          |
|             | > 2.Auto     |             |                          |
|             | graft/carbon |             |                          |
|             | > fiber      |             |                          |
|             | > reinforced |             |                          |
|             | > polymer    |             |                          |
|             | > device     |             |                          |
+-------------+--------------+-------------+--------------------------+

## IX.2.7.3 Posterolateral/Other Surgical Techniques

The efficacy studies listed below are presented as supporting
information which are relevant to the intended clinical use. These
studies were performed in order to gain information on the use of
rhBMP-2/ACS in the lumbar spine using different surgical techniques.

+-------------+--------------+-------------+--------------------------+
| **Study     | **Species    | **rh        | **Relevant Findings**    |
| Type**      | (n/          | BMP-2/ACS** |                          |
|             | grou         |             |                          |
|             | p)/Device(s) | **mg/site   |                          |
|             | tested**     | (mg/mL)**   |                          |
+=============+==============+=============+==========================+
| Lumbar with | Monkey (2)/  | 9 (1.5)     | Clinical evaluation,     |
| and without |              |             | radiography, CT scans,   |
| protective  | 1\.          | 18 (1.5)    | and histology: All       |
| p           | rhBMP-2/ACS  |             | monkeys treated with     |
| olyethylene |              |             | rhBMP-2 fused at 16      |
| shield      | 2\.          |             | weeks as assessed by     |
|             | r            |             | evaluation criteria.     |
|             | hBMP-2/ACS + |             | Animals with protective  |
|             | shield       |             | shield over fusion mass  |
|             |              |             | had more robust fusions  |
|             |              |             | despite lower dose of    |
|             |              |             | rhBMP-2                  |
+-------------+--------------+-------------+--------------------------+
| Lumbar      | rabbit       | 0 (0)       | Clinical evaluation,     |
|             | (4-16)/      |             | radiography, CT scans,   |
|             |              | 2.7 (0.64)  | and histology: All       |
|             | 1\.          |             | rabbits treated with     |
|             | rhBMP-2/ACS  |             | rhBMP-2 fused at 4 weeks |
|             |              |             | as assessed by           |
|             | 2\.          |             | evaluation criteria. 42% |
|             | autograft    |             | of autografts fused.     |
+-------------+--------------+-------------+--------------------------+
| Open vs.    | rabbit (16)/ | 0.24 (0.1)  | Clinical evaluation,     |
| minimally   |              |             | radiography, CT scans,   |
| invasive    | rhBMP-2/ACS  |             | and histology: All       |
| technique   |              |             | rabbits treated with     |
|             |              |             | rhBMP-2 fused at 10      |
|             |              |             | weeks as assessed by     |
|             |              |             | evaluation criteria.     |
+-------------+--------------+-------------+--------------------------+
| Lumbar      | > monkey     | 6.0 (1.36)  | Clinical evaluation,     |
|             | > (2-6)/     |             | radiography, CT scans    |
|             | >            | 9.0 (2.04)  | and histology: All       |
|             | > 1\.        |             | monkeys treated with     |
|             | >            | 12.0 (2.72) | rhBMP-2 fused at 24      |
|             |  rhBMP-2/BCP |             | weeks. No autograft      |
|             | >            |             | treated animals fused.   |
|             |  2.Autograft |             |                          |
+-------------+--------------+-------------+--------------------------+
| Lumbar:     | monkey (2)/  | 9.0 (2.04)  | Clinical evaluation,     |
| Comparison  |              |             | radiography, CT scans    |
| of calcium  | > 1\.        | 9.0 (1.50)  | and histology: All       |
| phosphate   | >            |             | monkeys treated with     |
| carriers    |  rhBMP-2/BCP | 4.5 (0.75)  | rhBMP-2/BCP and TCP      |
|             | >            |             | fused at 24 weeks.       |
|             | > 2\.        |             |                          |
|             | >            |             |                          |
|             |  rhBMP-2/TCP |             |                          |
|             | >            |             |                          |
|             | > 3\.        |             |                          |
|             | > r          |             |                          |
|             | hBMP-2/TCP + |             |                          |
|             | > collagen   |             |                          |
+-------------+--------------+-------------+--------------------------+
| P           | monkey (5)/  | 9.0 (2.04)  | Clinical evaluation,     |
| ercutaneous |              |             | radiography, CT scans    |
| technique   | >            |             | and histology: All       |
|             |  rhBMP-2/BCP |             | monkeys treated with     |
|             |              |             | rhBMP-2 fused at 24      |
|             |              |             | weeks. No autograft      |
|             |              |             | treated animals fused.   |
+-------------+--------------+-------------+--------------------------+
| Lumbar      | rabbit (11)/ | 0.90 (0.43) | Clinical evaluation,     |
|             |              |             | radiography, CT scans    |
|             | >            |             | and histology: The       |
|             |  rhBMP-2/BCP |             | rhBMP-2/BCP fusion       |
|             |              |             | masses were stiffer and  |
|             |              |             | stronger than autograft  |
|             |              |             | fusion mass controls.    |
+-------------+--------------+-------------+--------------------------+
| Lumbar      | dog (6)/     | 2.3/1.04    | Clinical evaluation,     |
|             |              |             | radiography, CT scans,   |
|             | > 1\.        |             | histology and            |
|             | >            |             | biomechanical testing:   |
|             | rhBMP-2/OPLA |             | All dogs treated with    |
|             | >            |             | rhBMP-2 fused at 12      |
|             | > 2\.        |             | weeks as assessed by     |
|             | > Autograft  |             | evaluation criteria. 8%  |
|             |              |             | of autografts fused.     |
+-------------+--------------+-------------+--------------------------+
| Lumbar:     | rabbit (12)/ | 1.0 (0.67)  | Clinical evaluation,     |
| rhBMP-2 and |              |             | radiography, and         |
| steroid     | > 1\.        |             | biomechanical testing:   |
| study       | > rhBMP-2    |             | 89% of rabbits treated   |
|             | >            |             | with rhBMP-2 fused       |
|             | > 2\.        |             | despite treatment with a |
|             | > Autograft  |             | steroid. None of the     |
|             |              |             | rabbits without rhBMP-2  |
|             |              |             | fused when treated with  |
|             |              |             | a steroid.               |
+-------------+--------------+-------------+--------------------------+
| Clinical    | > dog (11)   | 0 (0)       | Clinical evaluation,     |
| Ortho       | >            |             | radiography, histology   |
|             | > 1\.        | 0.4 (0.2)   | and biomechanical        |
| Rel Res     | > Autograft  |             | testing: Dogs treated    |
| p           | >            |             | with rhBMP-2 had equal   |
| ublication/ | > 2\. PGLA   |             | fusion rates to          |
|             | > par        |             | autograft.               |
| Posterior   | ticles/blood |             |                          |
| fusion with | > clots      |             |                          |
| plating     | >            |             |                          |
|             | > 3\.        |             |                          |
|             | >            |             |                          |
|             | rhBMP-2/PGLA |             |                          |
|             | > par        |             |                          |
|             | ticles/blood |             |                          |
|             | > clots      |             |                          |
+-------------+--------------+-------------+--------------------------+

## IX.2.7.4 Additional Information

The efficacy studies identified in the first table represent additional
information related to the use of the rhBMP-2 and ACS or other carriers
in the lumbar spine. These data may be considered ambiguous,
uninterpretable, or inconclusive, however, due to factors such as small
sample sizes, no controls, etc.

+-------------+--------------+--------------+-------------------------+
| **Study     | **Species    | **r          | **Relevant Findings**   |
| Type**      | (n/          | hBMP-2/ACS** |                         |
|             | grou         |              |                         |
|             | p)/Device(s) | **mg/site    |                         |
|             | tested**     | (mg/mL)**    |                         |
+=============+==============+==============+=========================+
| Interbody   |              |              |                         |
| fusion      |              |              |                         |
| studiess    |              |              |                         |
+-------------+--------------+--------------+-------------------------+
| Lumbar      | rabbit (2)/  | 0.48 (0.2)   | Clinical evaluation,    |
|             |              |              | radiography, CT scans,  |
|             | 1\.          | 0.96 (0.4)   | and histology: All      |
|             | rhBMP-2/ACS  |              | rabbits treated with    |
|             |              |              | rhBMP-2 fused at 4      |
|             | 2\.          |              | weeks as assessed by    |
|             | rhBMP-2/OPLA |              | evaluation criteria.    |
+-------------+--------------+--------------+-------------------------+
| Lumbar      | dog (3)/     | 0 (0)        | Clinical evaluation,    |
|             |              |              | radiography, CT scans,  |
|             | 1\.          | 0.054        | and histology: All dogs |
|             | rhBMP-2/ACS  | (0.023)      | treated with rhBMP-2    |
|             |              |              | fused at 12 weeks as    |
|             | 2\.          | 0.215 (0.09) | assessed by evaluation  |
|             | rhBMP-2/OPLA |              | criteria. 33% of        |
|             |              | 0.860 (0.36) | autografts fused.       |
|             | 3\.          |              |                         |
|             | Autograft    |              |                         |
+-------------+--------------+--------------+-------------------------+
| Lumbar      | dog (3)/     | 0.06 (0.025) | Clinical evaluation,    |
| without     |              |              | radiography, CT scans,  |
| de          | 1            | 0.23 (0.10)  | histology and           |
| cortication | .rhBMP-2/ACS |              | biomechanical testing:  |
|             |              | 0.92 (0.40)  | All dogs treated with   |
|             | 2\.          |              | rhBMP-2 fused at 12     |
|             | rhBMP-2/OPLA |              | weeks as assessed by    |
|             |              |              | evaluation criteria. No |
|             |              |              | statistical difference  |
|             |              |              | seen in carriers.       |
+-------------+--------------+--------------+-------------------------+
| Lumbar:     | > dog (3)/   | 0.43 (0.43)  | Clinical evaluation,    |
| A           | >            |              | radiography, CT scans,  |
| ugmentation | > 1\.        |              | histology and           |
| of          | > Autograft  |              | biomechanical testing:  |
| autograft   |              |              | Dogs treated with       |
| with        | 2\.          |              | rhBMP-2 had             |
| rhBMP-2     | rhBMP        |              | significantly increased |
|             | -2/Autograft |              | volumes of fusion mass  |
|             |              |              | compared to autograft.  |
|             | > 3\.        |              | No difference in        |
|             | > rhBMP-2/A  |              | carriers.               |
|             | CS/Autograft |              |                         |
|             | >            |              |                         |
|             | > 4\.        |              |                         |
|             | >            |              |                         |
|             |  rhBMP-2/ACS |              |                         |
|             | >            |              |                         |
|             | > 5\.        |              |                         |
|             | >            |              |                         |
|             | rhBMP-2/OPLA |              |                         |
|             | >            |              |                         |
|             | > 6\.        |              |                         |
|             | > rhBMP-     |              |                         |
|             | 2/Polylactic |              |                         |
|             | > Glycolic   |              |                         |
|             | > Acid       |              |                         |
|             | > Sponge     |              |                         |
|             | > (PGL       |              |                         |
|             | A)/Autograft |              |                         |
+-------------+--------------+--------------+-------------------------+
| Lumbar      | > monkey     | 6.0 (0.84)   | Clinical evaluation,    |
|             | > (1)/       |              | radiography, CT scans   |
|             | >            | 18.0 (1.68)  | and histology: All      |
|             | > 1\.        |              | monkeys treated with    |
|             | >            | 18.0 (2.53)  | rhBMP-2 fused at 24     |
|             |  rhBMP-2/BCP |              | weeks.                  |
|             | >            |              |                         |
|             | > 2\.        |              |                         |
|             | > rhBMP-2/   |              |                         |
|             | BCP/collagen |              |                         |
|             | >            |              |                         |
|             | > 3\.        |              |                         |
|             | > rhBMP-2/   |              |                         |
|             | > collagen   |              |                         |
+-------------+--------------+--------------+-------------------------+
| Lumbar:     | > dog (3-4)/ | 0.06 (0.025) | Clinical evaluation,    |
| Deco        | >            |              | radiography, CT scans,  |
| rtification | > un         | 0.23 (0.10)  | histology and           |
| vs. no      | decorticated |              | biomechanical testing:  |
| de          | >            | 0.92 (0.40)  | All dogs treated with   |
| cortication | >            |              | rhBMP-2 fused at 12     |
|             | rhBMP-2/OPLA |              | weeks as assessed by    |
|             |              |              | evaluation criteria     |
|             |              |              | except for one          |
|             |              |              | undecorticated low      |
|             |              |              | dose. No statistical    |
|             |              |              | difference in           |
|             |              |              | decorticated vs.        |
|             |              |              | undecorticated.         |
+-------------+--------------+--------------+-------------------------+
| Lumbar:     | > rabbit     | 3 (1.0)      | Clinical evaluation,    |
| rhBMP-2 and | > (9-17)/    |              | radiography, and        |
| NSAID study | >            |              | histology: All rabbits  |
|             | > 1\.        |              | treated with rhBMP-2    |
|             | > rhBMP-2    |              | fused despite treatment |
|             | >            |              | with an NSAID. 75% of   |
|             | > 2\.        |              | autografts fused        |
|             | > Autograft  |              | without NSAID           |
|             |              |              | treatment. 35% of       |
|             |              |              | autografts with NSAID   |
|             |              |              | treatment fused.        |
+-------------+--------------+--------------+-------------------------+
| Pos         |              |              |                         |
| terolateral |              |              |                         |
| fusion      |              |              |                         |
| studies     |              |              |                         |
+-------------+--------------+--------------+-------------------------+
| r           | > dog (1-5)/ | 0 (0)        | Clinical evaluation,    |
| hBMP-2/OPLA | >            |              | radiography and         |
| Pilot study | > 1\.        | 0.67 (1.04)  | histology: All dogs     |
|             | >            |              | treated with rhBMP-2    |
|             | rhBMP-2/OPLA |              | fused at 12 weeks as    |
|             | >            |              | assessed by evaluation  |
|             | > 2\.        |              | criteria.               |
|             | > rh         |              |                         |
|             | BMP-2/OPLA + |              |                         |
|             | > hyaluronic |              |                         |
|             | > acid       |              |                         |
+-------------+--------------+--------------+-------------------------+
| Lumbar:     | > dog (2)/   | 0 (0)        | Clinical evaluation,    |
| A           | >            |              | radiography, CT scans,  |
| ugmentation | > 1\.        | 2.0 (0.34)   | histology and           |
| of          | > Autograft  |              | biomechanical testing:  |
| autograft   | >            |              | Dogs treated with       |
| with        | >            |              | rhBMP-2 significantly   |
| rhBMP-2     | 2.Autograft/ |              | increased the number of |
|             | >            |              | fused levels compared   |
|             | > d          |              | to the controls at 24   |
|             | emineralized |              | weeks. In addition, the |
|             | > bone       |              | fusion masses were      |
|             | >            |              | larger with rhBMP-2.    |
|             | > 3\.        |              |                         |
|             | > Autogr     |              |                         |
|             | aft/collagen |              |                         |
|             | >            |              |                         |
|             | >            |              |                         |
|             | 4.Autograft/ |              |                         |
|             | >            |              |                         |
|             | > d          |              |                         |
|             | emineralized |              |                         |
|             | > b          |              |                         |
|             | one/collagen |              |                         |
|             | >            |              |                         |
|             | > 5\.        |              |                         |
|             | > rhBMP      |              |                         |
|             | -2/Autograft |              |                         |
+-------------+--------------+--------------+-------------------------+

## IX.2.7.5 Studies that demonstrate the ability of rhBMP-2 to fuse other bone defects

The efficacy studies listed in the following table represent the use of
rhBMP-2/ACS in the goat cervical spine model. All three of the studies
compared the efficacy of rhBMP-2/ACS to that of autogenous bone graft.

+------------+-------------+-------------+----------------------------+
| **Study    | **Species   | **rh        | **Relevant Findings**      |
| Type**     | (n/         | BMP-2/ACS** |                            |
|            | group       |             |                            |
|            | )/Device(s) | **mg/site   |                            |
|            | tested**    | (mg/mL)**   |                            |
+============+=============+=============+============================+
| Interbody  | goat (7)/   | 0.20 (0.40) | Clinical evaluation,       |
| fusion     |             |             | radiography, CT scans,     |
|            | 1\.         |             | histology and              |
|            | rhBMP-2/A   |             | biomechanical testing: 95% |
|            | CS/titanium |             | of goats treated with      |
|            | cage        |             | rhBMP-2 fused at 12 weeks  |
|            |             |             | as assessed by             |
|            | 2\.         |             | histological evaluation.   |
|            | Autogra     |             | 48% of autografts fused.   |
|            | ft/titanium |             |                            |
|            | cage        |             |                            |
+------------+-------------+-------------+----------------------------+
| Interbody  | > goat (8)  | 0.20 (0.40) | Radiography, CT scans,     |
| fusion     |             |             | histology and              |
|            | 1\.         |             | biomechanical testing: 67% |
|            | rhBMP-2/A   |             | of levels treated with     |
|            | CS/titanium |             | rhBMP-2 fused at 12 weeks. |
|            | cage        |             | 47% of autografts fused.   |
|            |             |             |                            |
|            | > 2\.       |             |                            |
|            | > Autogra   |             |                            |
|            | ft/titanium |             |                            |
|            | > cage      |             |                            |
|            | >           |             |                            |
|            | > 3\.       |             |                            |
|            | > tantalum  |             |                            |
|            | > cage      |             |                            |
|            | >           |             |                            |
|            | > 4\.       |             |                            |
|            | > rhBMP-2   |             |                            |
|            | > tantalum  |             |                            |
|            | > cage      |             |                            |
+------------+-------------+-------------+----------------------------+
| Interbody  | > goat (3)  | 0.17 (0.43) | Radiography, histology and |
| fusion     | >           |             | biomechanical testing:     |
|            | > 1\.       |             | Radiographic scores higher |
|            | >           |             | for autograft than for     |
|            | rhBMP-2/ACS |             | rhBMP-2. Difference was    |
|            | >           |             | not statistically          |
|            | > 2\.       |             | significant.               |
|            | > Autograft |             |                            |
+------------+-------------+-------------+----------------------------+

## IX.2.7.6 Preclinical Evaluations Conclusions

No evidence of any neurological abnormalities was found in studies
performed to evaluate the safety of rhBMP-2/ACS in the vicinity of the
spinal cord and nerve roots. In addition, there was no evidence, based
on blood and cerebrospinal fluid analyses, of any clinical abnormalities
in the animals tested. There was also no radiographic or histologic
evidence of mineralization within the thecal sac.

In studies comparing fusion in the presence of rhBMP-2/ACS vs. autograft
bone, the histological fusion rate was greater for the rhBMP-2/ACS
treated animals than for the animals receiving autograft bone. In a
study comparing rhBMP-2/ACS to ACS alone, all animals treated with
rhBMP-2/ACS had solid interbody fusions while neither of the animals
receiving ACS alone were fused. The animals receiving the higher dose of
rhBMP-2 had qualitatively denser bone compared to those in the lower
dose group. These studies indicate that rhBMP-2/ACS was able to induce
interbody spinal fusion in a variety of interbody constructs.

rhBMP-2/ACS demonstrated effectiveness in promoting posterolateral
spinal fusion using both open and minimally invasive surgical
techniques.

In the studies in which the rhBMP-2/ACS or autogenous bone was placed
inside a titanium alloy spinal fusion cage, the fusion rate of the
rhBMP-2/ACS group was higher than that of the autograft control. When
anterior plates were used instead of spinal fusion cages, the
radiographic fusion scores of the rhBMP-2/ACS group were higher, but the
difference was not statistically significant. These studies demonstrated
the ability of rhBMP-2/ACS to stimulate interbody fusion of the cervical
spine in a manner at least equivalent to, if not better than autograft.

**X. SUMMARY OF CLINICAL STUDIES**

### 

# X.1 PILOT STUDY {#x.1-pilot-study .Style1}

Prior to initiating enrollment in a large-scale clinical trial, the
sponsor conducted a small prospective, multi-center, non-blinded,
randomized pilot study (14 subjects, 11 investigational and 3 control,
at 4 sites). This study utilized the same study design, control and
investigational devices, enrollment criteria, clinical and radiographic
evaluation parameters and evaluation time points as the subsequent,
large-scale study (these parameters are described in detail in Section
X.2 below). The sponsor enrolled 14 subjects in this study - 7 open
anterior surgical approach investigational subjects, 4 laparoscopic
surgical approach investigational subjects and 3 open anterior surgical
approach control subjects. At 48 months, data for 9 subjects (6
investigational and 3 control) were available for analysis.

# X.1.1 Clinical and radiographic effectiveness parameters

Pain and function were assessed with the Oswestry Low Back Pain
Disability Questionnaire and neurological status was assessed from an
evaluation of muscle strength, reflexes, sensation and straight leg
raises (SLR). The fusion endpoint was assessed using lateral
flexion/extension films to evaluate the presence of motion and
reconstructed sagittal CT scans to evaluate the presence of bridging
trabecular bone. Plain radiographs were used to assess disc height and
implant subsidence.

# X.1.2 Clinical and radiographic effectiveness evaluation

At 24 months post-op, 91% (10/11) investigational and 100% (2/2) control
subjects were determined to be successes in terms of their pain and
function scores. By 48 months post-op, 1/2 control subjects with data
had maintained their improvement from baseline pre-op levels. 4/7
investigational subjects maintained an improved score and 1 had a worse
score. In addition, all but one subject (6 investigational, 2 control)
reported less pain compared to their pre-baseline op scores with 5 of
these subjects reporting no post-op pain.

At 24 month post-op evaluation, all investigational and control subjects
were considered neurological successes in terms of motor, sensory and
SLR scores. Only 9/11 (81.8%) investigational subjects were considered
as successes for reflexes compared to 100% of the control subjects. At
48 months, 6 investigational subjects reported their overall
postoperative neurological condition to be no worse than preoperatively.

All 11 investigational group subjects were found to be fused at 6, 12,
and 24 months post-op. Only 2 of 3 control group subjects were
determined to be fused at 6 months. At 18 months, the control subject
not fused at 6 months underwent a second surgical intervention for
implantation of supplemental fixation. At 48 months all 8 patients with
radiographic data were fused.

**X.1.3 Safety and immune response evaluation**

For the investigational group, 8 of 11 subjects (72.7%) reported a total
of 21 adverse events compared to 3 of 3 subjects (100%) for the control
group. Three patients, 1 investigational and 2 control, were diagnosed
as having pseudarthrosis. Other transient adverse events included
urinary retention (1 control subject), numbness (1 investigational
subject), facet joint pain (1 investigational subject), wound dehiscence
(1 investigational subject) and back pain (2 investigational subjects).
There were no episodes of retrograde ejaculation or anatomic and/or
technical difficulties reported for the investigational laparoscopic
approach group. No adverse events were reported at the 48 month visit.

Antibodies to rhBMP-2 and bovine and human Type I collagen were
assessed. Antibodies were evaluated at three timepoints -- pre-op and 6
weeks and 3 months post-op. None of the 14 subjects exhibited antibodies
to rhBMP-2. Two subjects exhibited positive antibody responses to bovine
Type I collagen at 6 weeks. Two of these remained positive at 3 months.
No subjects were positive for antibodies to human Type I collagen. All
subjects with positive antibody responses were determined to have
radiographic fusion at their last examination.

## 

## X.2 PIVOTAL STUDY

## X.2.1 Study Background

Clinical data to support the safety and effectiveness of the InFUSE™
Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device were collected as part
of a prospective, multi-center study that consisted of randomized and
non-randomized arms. The randomized arm contained two groups, one
investigational and one control. The control group was implanted with
the LT-CAGE™ Lumbar Tapered Fusion Device filled with iliac crest
autograft bone, while the investigational group was implanted with the
InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device. In both cases,
the surgical approach was an open anterior approach. The non-randomized
arm contained only an investigational group, where subjects were
implanted with the InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion
Device through a laparoscopic anterior approach. The control group from
the randomized arm was used as the control for the non-randomized arm.

Neither the investigators nor the subjects were blinded to the
treatment. Subject blinding was not possible due to the second surgical
site resulting from the need to collect the iliac crest grafts. The
potential for investigator bias in the clinical outcome parameters was
reduced by having the subjects rate their outcome using objective
self-assessments. The radiographic outcome parameters were preformed by
independent radiologists who were blinded to treatment. These were the
only radiographic evaluations used for determining radiographic success.

**X.2.2 Inclusion criteria**

The indication studied was degenerative disc disease (DDD) accompanied
by back pain with or without leg pain at a single level between L~4~ and
S~1~ confirmed by history and radiographic studies. DDD was determined
to be present if one or more of the following were noted:

-   instability (defined as angulation ≥ 5° and/or translation ≥ 4mm on
    flexion/extension radiographs);

-   osteophyte formation;

-   decreased disc height;

-   ligamentous thickening;

-   disc degeneration/herniation; or

-   facet joint degeneration.

The following additional inclusion criteria had to be present:

-   a pre-op Oswestry Low Back Pain Disability Questionnaire score of 35
    or more;

-   if spondylolisthesis were present, it could be no greater than grade
    I;

-   be non-responsive to non-operative treatment for at least 6 months;

-   skeletally mature; and

-   not pregnant or nursing and agrees to the use of contraception for
    at least 16 weeks post-implantation.

**X.2.3 Exclusion criteria**

Subjects were excluded if they had any of the following:

-   previous anterior spinal fusion at the involved level;

-   posterior spinal instrumentation at the involved level or a previous
    interbody fusion procedure;

-   any conditions that require postoperative medications that would be
    expected to interfere with fusion, *e.g.*, steroids, or has received
    drugs that interfere with bone metabolism within 2 weeks of surgery;

-   osteoporosis, osteopenia, or osteomalacia;

-   active malignancy;

-   active local or systemic infection;

-   gross obesity, defined as \>40% IBW;

-   fever \>101°F;

-   mentally incompetent;

-   Waddell Signs of Inorganic Behavior ≥3;

-   alcohol or drug abuse;

-   tobacco user;

-   an autoimmune disease;

-   titanium allergy;

-   previous exposure to injectable collagen implants;

-   hypersensitivity to protein pharmaceuticals or collagen;

-   previous exposure to rhBMP-2;

-   allergy to bovine products or history of anaphylaxis;

-   endocrine or metabolic disorder that affects osteogenesis; or

-   received another investigational therapy within 28 days prior to
    implantation.

**X.2.4 Post-operative care**

The recommended post-operative care included the use of external
immobilization for 6 weeks; abdominal strengthening exercises starting
30 days post-op; avoidance of repetitive bending, lifting, stooping,
twisting and athletic activities until fusion had occurred; avoidance of
prolonged NSAID use and prohibition of the use of electrical bone growth
stimulators within 24 months post-op.

# X.2.5 Clinical and radiographic effectiveness parameters

Patients were evaluated preoperatively (within 6 months of surgery),
intraoperatively, and postoperatively at 6 weeks, 3, 6, 12 and 24 months
and biennially thereafter until the last subject enrolled in the study
had been seen for their 24 month evaluation. Complications and adverse
events, device-related or not, were evaluated over the course of the
clinical trial. At each evaluation timepoint, the primary and secondary
clinical and radiographic outcome parameters were evaluated. Success was
determined from data collected during the initial 24 months of
follow-up. Antibodies to rhBMP-2 and bovine Type I collagen were
assessed preoperatively and at 3 months post-operatively. Antibodies to
human Type I collagen were assessed if the antibody response to bovine
Type I collagen was positive.

Primary and secondary clinical and radiographic effectiveness outcome
parameters were evaluated for all treated subjects at all follow-up
evaluation timepoints identified above. The primary clinical parameters
assessed were of pain, function and neurological status. The secondary
clinical outcome parameters assessed were general health status, back
and leg pain, donor site pain (control subjects only), patient
satisfaction and patient global perceived effect of the treatment. The
primary radiographic outcome parameter consisted of evaluations of
fusion, while the secondary radiographic assessment was disc height.

Fusion was evaluated at 6, 12 and 24 months post-op using plain
radiographs (AP, lateral and flexion/extension films) and high
resolution thin-slice CT scans (1mm slices with 1mm index on axial
sagittal and coronal reconstructions). Fusion was defined as the
presence of bridging bone connecting the inferior and superior vertebral
bodies; a lack of motion on flexion/extension (≤ 3mm of translation and
\< 5° of angulation); and no evidence of radiolucencies over more that
50% of either implant. Fusion success was defined as the presence of all
of these parameters plus the lack of a second surgical intervention
resulting from a non-union. All assessments were made from the plain
films except for the assessment of bridging bone, which was made using
the CT scans only if bridging bone could not be visualized on the plain
film.

Pain and function were measured using the Oswestry Low Back Pain
Disability Questionnaire. Success was defined as a 15 point improvement
in the Oswestry score from the pre-op baseline score.

Neurological status consisted of measurements of four parameters -
motor, sensory, reflexes, and SLR. Neurological status success was
defined as maintenance or improvement of the pre-op baseline score for
each parameter. Overall neurological status success required that each
individual parameter be a success for that subject to be counted as a
success.

**X.2.6 Patient demographics and accountability**

The study was limited to 16 open surgical approach sites with 135
subjects per group (270 total open approach subjects) and 15
laparoscopic approach sites with 135 total subjects. This was
subsequently modified to allow termination of enrollment of the open
approach sites when 300 total subjects or 135 per group were reached. No
changes were made to the laparoscopic approach site limits.

A total of 143 open approach investigational and 136 control patients
were enrolled in the randomized arm of the study and received the
device. A total of 134 subjects were enrolled in the non-randomized arm
of the study and received the device. For the majority of the
demographic parameters, there were no differences in pre-op demographics
across the three populations.

  -----------------------------------------------------------------------------
  **Subject                                                
  demographics**                                           
  -------------------- ------------------- --------------- --------------------
                       **Investigational   **Control Open  **Investigational
                       Open Surgical       Surgical        Laparoscopic
                       Approach**          Approach**      Surgical Approach**

  n                    143                 136             134

  men/women            78/65               68/68           57/77

  mean age (range)     43.3 (22.4 -- 78.4) 42.3 (19.0 --   42.4 (19.2 -- 69.5)
                                           70.6)           

  weight (lbs)         179.1               181.1           169.8

  worker's comp (%)    47 (32.9)           47 (34.6)       42 (31.3)

  tobacco user (%)     47 (32.9)           49 (36.0)       40 (29.9)

  previous back        54 (37.8)           55 (40.4)       33 (24.6)
  surgery (%)                                              
  -----------------------------------------------------------------------------

For the majority of the evaluation timepoints for all investigational
groups, the follow-up rate was greater than 90%. For a small number of
subjects, complete 24 month data for all effectiveness variables were
not available, however. In order to "complete" the 24 month dataset for
the subjects with missing data, 24 month values were predicted from the
existing 12 month data using Bayesian statistical methods.

An analysis was performed to assess the ability to pool data across
sites and to compare data across the study arms. These analyses
evaluated the primary clinical outcome variables, as well as overall
success and found no differences that would prevent pooling of the data
across the sites within a given group of subjects.

Surgical results and hospitalization

  ----------------------------------------------------------------------------
  **Surgical and                                         
  hospitalization                                        
  information**                                          
  ------------------- ------------------- -------------- ---------------------
                      **Investigational   **Control Open **Investigational
                      Open Surgical       Surgical       Laparoscopic Surgical
                      Approach**          Approach**     Approach**

  mean operative time 1.6                 2.0            1.9
  (hrs)                                                  

  mean EBL (ml)       109.8               153.1          146.1

  hospitalization     3.1                 3.3            1.2
  (days)                                                 

  spinal level                                           
  treated                                                

  L~45~ (%)           37 (25.9)           32 (23.5)      21 (15.7)

  L~5~S~1~ (%)        106 (74.1)          103 (75.7)     113 (84.3)

  L~56~ (%)           0 (0)               1 (0.7)        0 (0)
  ----------------------------------------------------------------------------

While not statistically significant, the operative time and mean blood
loss for the investigational open surgical approach subjects were lower
than for the other two groups and the investigational laparoscopic
surgical approach subjects required fewer hospitalization days.

# X.2.7 Clinical and radiographic effectiveness evaluation

Individual subject success was defined as success in each of the primary
clinical and radiographic outcome parameters. Success for these
parameters included:

1\. the presence of radiographic fusion;

2\. an improvement of at least 15 points from the baseline Oswestry
score;

3\. maintenance or improvement in neurological status;

4\. the presence of no serious adverse event classified as
implant-associated or implant/surgical procedure-associated; and

5\. no additional surgical procedure classified as "Failure."

Study success was expressed as the number of individual subjects
categorized as a success divided by the total number of subjects
evaluated. The table below describes the success rates for the
individual primary outcome parameters and overall success. All success
rates were based on the data from the 24 month follow-up evaluation and
posterior probabilities of success were calculated using Bayesian
statistical methods.

+--------+-------------------+-------------------+--------------------+
| **Pos  |                   |                   |                    |
| terior |                   |                   |                    |
| P      |                   |                   |                    |
| robabi |                   |                   |                    |
| lities |                   |                   |                    |
| of     |                   |                   |                    |
| S      |                   |                   |                    |
| uccess |                   |                   |                    |
| at 24  |                   |                   |                    |
| Mo     |                   |                   |                    |
| nths** |                   |                   |                    |
+========+===================+===================+====================+
| P      | **Investigational | **Control Open    | **Investigational  |
| rimary | Open Surgical     | Surgical          | Laparoscopic       |
| o      | Approach**        | Approach**        | Surgical           |
| utcome |                   |                   | Approach**         |
| va     |                   |                   |                    |
| riable |                   |                   |                    |
+--------+-------------------+-------------------+--------------------+
|        | Posterior Mean    | Posterior Mean    | Posterior Mean     |
|        |                   |                   |                    |
|        | (95% HPD Credible | (95% HPD Credible | (95% HPD Credible  |
|        | Interval)         | Interval)         | Interval)          |
+--------+-------------------+-------------------+--------------------+
| Fusion | 92.8%             | 88.1%             | 93.0%              |
|        |                   |                   |                    |
|        | (88.5%, 96.9%)    | (82.6%, 99.3%)    | (87.9%, 97.5%)     |
+--------+-------------------+-------------------+--------------------+
| Os     | 71.0%             | 70.9%             | 83.0%              |
| westry |                   |                   |                    |
|        | (63.4%, 78.7%)    | (63.1%, 79.1%)    | (75.6%, 90.5%)     |
+--------+-------------------+-------------------+--------------------+
| Neur   | 81.0%             | 81.7%             | 89.0%              |
| ologic |                   |                   |                    |
|        | (74.5%, 87.9%)    | (74.9%, 88.7%)    | (83.1%,94.8%)      |
+--------+-------------------+-------------------+--------------------+
| O      | 57.1%             | 56.7%             | 68.0%              |
| verall |                   |                   |                    |
| s      | (49.2%, 65.7%)    | (48.3%, 65.0%)    | (59.3%, 76.5%)     |
| uccess |                   |                   |                    |
+--------+-------------------+-------------------+--------------------+

The probability (also called the posterior probability) that the 24
month overall success rate for the investigational groups was equivalent
to the 24 month success rate for the control group was 99.4% for the
open surgical approach investigational group and almost 100% for the
laparoscopic surgical approach investigational group.

For a future patient receiving the InFUSE™ Bone Graft/LT-CAGE™ Lumbar
Tapered Fusion Device via the open anterior surgical approach, the
chance (the predictive probability) of overall success at 24 months
would be 57.1% for the open surgical approach. Given the results of the
trial, there is a 95% probability that the chance of success ranges from
49.2% to 65.7% For a future patient receiving the InFUSE™ Bone
Graft/LT-CAGE™ Lumbar Tapered Fusion Device via the anterior
laparoscopic surgical approach, the chance of overall success at 24
months would be 68.0%. Given the results of the trial, there is a 95%
probability that the chance of success ranges from 59.3% to 76.5%. For a
future patient receiving the control treatment, the chance of overall
success at 24 months would be 56.7%. Given the results of the trial,
there is a 95% probability that the chance of success ranges from 48.3%
to 65.0%.

**X.2.8 Safety and immune response evaluation**

The assessment of safety consisted of an evaluation of the reported
adverse events, as well as an evaluation of antibodies to rhBMP-2,
bovine Type I collagen and human Type I collagen. The complete list of
complications, adverse events and subsequent interventions is described
in section VIII above. The presence of antibodies were assessed at the
pre-op and 3 month post-op visits using ELISA. If there was a positive
response to bovine Type I collagen, the serum was also tested for
antibodies to human Type I collagen. The screening ELISA cutpoint for
positive antibody responses was set to 5 times the standard deviation of
sera from normal human donors. Subjects were considered to have an
elevated immune response if the preoperative test was negative (titer \<
50) and postoperative test was positive (titer ≥ 50) or if the
preoperative test was positive and the postoperative test was positive
with a three-fold higher titer than the preoperative test.

There were 3 subjects who had positive antibody responses to rhBMP-2 --
1 subject in each of the study groups. The rates of positive antibody
response to rhBMP-2 were 0.7% in the open surgical approach
investigational group and 0.8% in the laparoscopic surgical approach
investigational and open surgical approach control groups. While there
is a theoretical possibility that antibodies to rhBMP-2 could neutralize
endogenous BMP-2, thereby interfering with subsequent bone healing, this
was not observed during the course of the study.

Sixty-six subjects were considered to have an authentic elevated
antibody response to bovine Type I collagen - 18 open surgical approach
investigational subjects, 32 laparoscopic surgical approach
investigational subjects and 16 control subjects. No subjects had
positive responses to human Type I collagen.

An evaluation was performed on the impact of a positive antibody
response on overall success and fusion success. There was very little
difference in overall and individual success when antibody status was
taken into consideration.

During the course of the study, 6 pregnancies were reported -- one in
the control group and five in the investigational groups. Two of the
four pregnancies that occurred in the laparoscopic approach group
resulted in first trimester miscarriages. The other three pregnancies in
the investigational groups resulted in live births with no reported
complications. None of the pregnant subjects had antibody responses to
rhBMP-2 or Type I collagen (bovine or human), that were detectable to
the limits of the sensitivity of the assay.

Two cases of cancer were diagnosed during the course of the pivotal
study -- one in an investigational group and one in the control group.
An investigational subject was found to have pancreatic cancer while a
control subject was found to have breast cancer. No additional
information is available on these subjects, *e.g.*, BMP-2 receptor
expression.

# XI. CONCLUSIONS DRAWN FROM THE STUDIES

All of the data provided in the previous sections describing the
preclinical and clinical studies provide reasonable assurance of the
safety and effectiveness of the InFUSE™ Bone Graft/LT-CAGE™ Lumbar
Tapered Fusion Device when used by well-trained surgeons via anterior
open or laparoscopic surgical approaches for spinal fusion procedures in
skeletally mature patients with DDD at one level from L~4~-S~1~. DDD is
defined as discogenic back pain with degeneration of the disc confirmed
by patient history, function deficit and/or neurological deficit and
radiographic studies. These DDD patients may also have up to Grade I
spondylolisthesis at the involved level.

The study demonstrated that treatment of DDD with the InFUSE™ Bone
Graft/LT-CAGE™ Lumbar Tapered Fusion Device was as effective as the
control treatment (the LT-CAGE™ Lumbar Tapered Fusion Device filled with
iliac crest autograft). The results for the primary effectiveness
outcome parameters for both investigational groups were equivalent to
the control group. The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion
Device was able to achieve comparable clinical performance while
avoiding the necessity of an iliac crest graft site and its associated
pain.

**XII.** **PANEL RECOMMENDATION**

The PMA was reviewed at the Orthopedic and Rehabilitation Devices
Advisory Panel meeting held on January 10, 2002. The Panel unanimously
recommended to the FDA that the application for the InFUSE™ Bone
Graft/LT-CAGE™ Lumbar Tapered Fusion Device was approvable on the
following conditions:

-   the labeling should clearly identify:

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-   the approved anterior open and laparoscopic surgical approaches;

-   the specific tapered spinal fusion cage to be used; and

-   the use of the device at a single involved lumbar spinal level; and

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-   the sponsor should perform the following nonclinical post approval
    studies:

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-   an evaluation of BMP receptor expression determination and *in
    vitro* proliferation evaluation in primary tumor cell isolates;

-   an evaluation of the ability of rhBMP-2 antibodies to cause
    reproductive problems in all stages of fetal development from
    implantation to birth; and

-   an evaluation of the response of mice to equal, multiple does of
    rhBMP-2 over a 1 year period.

**XIII. CDRH DECISION**

FDA concurred with the Panel's recommendations regarding additional
studies involving determining primary tumor cell BMP receptor status and
primary tumor cell *in vitro* responsiveness to rhBMP-2. In addition,
FDA agreed with the Panel's recommendation for experiments to evaluate
the potential for maternal antibodies to rhBMP-2 to interfere with
embryonic development. The agency did not agree with the recommendation
to evaluate toxic effects due to multiple doses of rhBMP-2 in mice over
a one-year period for the following reasons:

-   The sponsor had already conducted a one-year rat study and a 6-month
    dog study and found no device-related toxicities;

-   The device is not intended to be implanted multiple times in
    prospective patients. The one-year rat study conducted by the
    sponsor evaluated the product under conditions analogous to that for
    which the product was intended to be used.

-   The sponsor has conducted many animal studies to evaluate device
    performance. Repeat administration of rhBMP-2 in dogs and rats was
    evaluated to 28 days post-exposure. FDA believes that the rodent
    model suggested by the Panel would not provide additional safety
    information regarding the product that has not already been obtained
    from other studies.

As a result, the sponsor was required to perform only the first two
studies recommended by the advisory panel. Specifically, the sponsor was
required to perform:

-   studies to assess the effects of rhBMP-2 on tumor promotion. These
    investigations included *in vitro* studies with primary tumor cell
    isolates. Observations from these studies could indicate a necessity
    to modify the device's labeling.

-   studies to investigate the potential for an immune response to
    rhBMP-2 to interfere in embryonic development in rabbits.
    Observations from these studies could indicate a necessity to create
    a pregnancy monitoring database or modify the device's labeling.

In order to gather long-term safety and effectiveness data, the sponsor
must conduct a post approval study to obtain six-year follow-up data
from a statistically-justified number of patients. Because of the
unknown long-term device performance, particularly the resulting bony
fusion characteristics, the post-approval study will include analysis of
any retrieved implants.

Furthermore, the sponsor also agreed to develop the following assays in
order to better define the immunological response to rhBMP-2 :

-   development and validation of a new ELISA for rhBMP-2 that is
    capable of detecting all antibody isotypes; and

-   development and validation of an assay which is capable of detecting
    neutralizing antibodies to rhBMP-2.

Finally, the sponsor was required to submit reports on three additional
assays, *i.e.*, silver stained SDS-PAGE, Edmans test and glycoform
analysis, to be added to the release specifications for the rhBMP-2
device component.

FDA worked with the sponsor to finalize product labeling and the
requirements of the post approval studies. The sponsor's manufacturing
facilities were inspected and were found to be in compliance with the
Quality Systems Regulation (21 CFR 820).

[]{.mark}

FDA issued an approval order on July 2, 2002.

The InFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device was granted
expedited review status on January 12, 2001, because FDA believed that
the possibility of reducing or removing the morbidity associated with
the harvested autograft bone donor site through the use of a growth
factor-soaked collagen sponge within the fusion cage offered an
improvement to patient care.

**XIV. APPROVAL SPECIFICATIONS**

Directions for Use: See product labeling

Hazard to Health from Use of the Device: See Indications,
Contraindications, Warnings, and Precautions, and Adverse Reactions in
the labeling.

Post Approval Requirements and Restrictions: See the Approval Order.