February 5, 2003

Final Statistical Review for PMA P020012, Artecoll PMMA/Collagen Implant
for Correction of Contour Deficiencies of Soft Tissue, Artes Medical
USA, Inc.

[Background]{.underline}

Artecoll is a suspension of polymethyl Methacrylate (PMMA) microspheres
in a 3.5% collagen solution. It is intended as an injectable filler for
the long lasting correction of dermal defects. The original IDE
application (G970026) was submitted by Rofil Medical USA. One hundred
fifty-seven subjects were treated with Artecoll. There was no control
group. In 1999, the responsibility of the study was transferred to Artes
Medical, and a new clinical study was initiated. This was a prospective,
multi-center, controlled, randomized, double masked trial. Two hundred
fifty-one subjects were randomized (1:1) to either Artecoll or a
commercially available collagen implant (Zyderm2 for glabellar folds,
Zyplast for the other 3 areas (nasolabial folds, upper lip lines, mouth
corners). Follow-ups for safety and efficacy were at 1,3, and 6 months,
with a final safety evaluation at 12 months. The primary objectives were
to determine if the cosmetic correction provided by Artecoll was
superior to the control at the end of 6 months, and to determine the
safety of Artecoll. The Facial Fold Assessment (FFA) Scale was created
and validated for this study. Secondary objectives were to compare the
initial quality of the correction between the two treatment groups and
to compare (unmasked) investigator assessment and patient satisfaction.

[Reviewer\'s Comments]{.underline}

Because there were large differences in favor of Artecoll between the
masked observer and unmasked investigator/patient satisfaction, I find
that the unmasked analyses could be biased, and my comments will focus
on the masked FFA assessments unless otherwise noted. The sponsor\'s
argument that the differences between results in the masked and unmasked
analyses could be due to looking at a 2-dimensional photo verses a
3-dimensional live person should be evaluated from a clinical
perspective. The data from the early Rofil study, may be used for
safety, but is of little use for efficacy since there were different
outcome measures and no control. The Rofil study will not be directly
addressed in this review. All references to tables and figures will
apply either to Volume 12 of the original PMA, Amendment 9 (October 16,
2002), or Amendment 13 (January 23, 2003). Because all treatment areas
were bilateral, scores were averaged across right and left sides of the
face and also across multiple masked observers.

*Changes from Baseline*

Although not specifically a study endpoint, one must look first at the
individual efficacy of each treatment. The sponsor has shown a
statistically significant improvement from baseline to 6 months for 3
out of the 4 Artecoll areas and 2 out of 4 control areas. It should be
noted that nasolabial folds is not one of the control areas that
remained improved at 6 months, which brings up the possibility of an
inactive control for this area. This is particularly important should
the sponsor ever decide to switch to a non-inferiority claim in the
future. The issue here, however, is whether Artecoll is
[more]{.underline} effective than the control, and that is what the
sponsor's analyses focused on.

*Study Results*

The sponsor's claim was that the [magnitude]{.underline} of the
improvement with Artecoll would be statistically superior to the
magnitude of the improvement with the control. For this primary
endpoint, the data did not support the claim for any treatment area
except nasolabial folds. Early on, at months 1 and 3, the control was
actually numerically superior to Artecoll for efficacy of glabellar
folds and upper lip lines. By 6 months, Artecoll scores were
statistically significantly superior for nasolabial folds (p\<0.001),
although the difference in the mean improvements between the two
treatment groups was 0.77 points on the FFA scale, which was less than
the 1.0 point identified as clinically significant at the study design
phase. To control type 1 error from the fact that four areas of the
faces were tested on the same individual (multiplicity), the sponsor
divided alpha by 4 (i.e., 0.05/4 = 0.0125), which is akin to doing a
"Bonferonni Adjustment", and their P\<0.001 was still statistically
significant at the stricter level. The sponsor used the Mann-Whitney U
Test. This is the nonparametric equivalent of the two sample t-test, and
its use is appropriate for non-normally distributed data. However,
because the Artecoll group had a statistically worse pretreatment
wrinkle severity rating for nasolabial folds, it can be argued that the
Artecoll group had more room for improvement. Thus, further analyses
were necessary to adjust for these pretreatment differences.

*Pretreatment Differences*

The sponsor performed several supplemental analyses to adjust for these
pretreatment wrinkle severity differences. The first one, a covariate
analysis (ANCOVA), showed that treatment effect remained statistically
significant after adjusting for differences in pretreatment wrinkle
severity (Table 43, Vol. 12). The actual adjusted means are shown in
Table 44, and the adjusted treatment effects for Artecoll dropped
slightly from 0.77 to 0.71 points on the FFA scale. The difference
between Artecoll and control also dropped from 0.77 to about 0.65.
Although a covariate analysis is generally an appropriate way to adjust
for baseline differences, it is a parametric procedure that is based on
the assumption of normally distributed data. Since these data were not
normally distributed, the validity of this adjustment remains in
question. The following table shows the unadjusted and adjusted means
for the masked assessment of nasolabial folds.

Mean Nasolabial Fold Masked FFA Scale Improvement at Six Months

  ----------- ---- -------------- ------------ ----------- ----------------
  Treatment   N    Unadj. Means   Tx Diff      Adj. Means  Adj.Tx Diff
                                  (A-C)                    (A-C)

  Artecoll    92   0.77           0.77         0.712       0.654

  Control     91   0.00           (p\<0.001)   0.058       (p\<0.001)
  ----------- ---- -------------- ------------ ----------- ----------------

The sponsor performed 3 other analyses to adjust for pretreatment
severity, 2 of which were non-parametric and not subject to assumptions
of normality (an analysis restricting the cases to nasolabial folds with
pretreatment severity ratings of at least 1, and an analysis of 55 pairs
randomly matched on pretreatment severity). The statistical superiority
of Artecoll was maintained for nasolabial folds for all adjustment
techniques. As shown in the table below, when the analysis was
restricted to only those cases who had the ability to improve 1 point or
more, the mean improvement was 0.99 points for Artecoll and 0.28 points
for the control, the difference being 0.71, virtually identical to the
adjustment using the covariate analysis above.

Mean Nasolabial Fold Masked FFA Scale Improvement at Six Months

For Subjects with Initial Pretreatment Severity of least 1.0

  -------------- ------- --------- -------------- -------------- ------------------
  Treatment      N       Mean      Tx Diff (A-C)  Mann-Whitney   
                                                  Test           

  Artecoll       67      0.99      0.71           U              p-value

  Control        53      0.28                     935.5          \<0.001
  -------------- ------- --------- -------------- -------------- ------------------

*Follow-up and Attrition*

Six-month follow-up was available on 229 (91.2%) of the subjects. The
sponsor performed an ANOVA showing subjects without 6-month follow-up
had similar results at 1 and 3 months to patients having 6-month
follow-up (Vol.12, Table 39). There were no significant differences
between those with 6-months data and those without, and no \"treatment
by attrition interaction\". This means that, for a given area of the
face, you didn\'t have one device working better for those with 6-month
follow-up and the other working better for those without. There was a
consistent pattern. Although the same problem of using parametric
statistics exists as with the discussion above, I don\'t think attrition
is an issue here given that it was generally less than 9% of the study
population.

*Timing of Follow-up Visits*

Another concern is all the protocol deviations in the timing of
follow-up visits. One-third to one-half of the subjects, depending on
treatment area, were lost when the analysis is limited to only cases
meeting protocol timing restrictions for [every]{.underline} follow-up
visit (compare Vol. 12,Tables 55 and 26). However, the results for this
subgroup analysis are still statistically significant for nasolabial
folds. Further, the primary efficacy endpoint was an analysis of change
from baseline to 6 months, so deviations in timing of earlier follow-up
visits are of little consequence.

*Poolability across Centers*

There were some significant differences in masked pretreatment wrinkle
severity scores across centers, but these occurred for the treatment
areas of upper lip lines and mouth corners. Since these areas did not
meet the endpoint for the masked analysis, it is really a moot point.
There were no significant study center differences in outcome.
Therefore, I consider the data to be poolable across centers.

*Averaging across Masked Observers*

As mentioned earlier, scores from masked assessments for a given
treatment area on a given face were averaged across masked observers and
between sides of the face. Because all this averaging could result in a
loss of information, I requested an analysis stratified by masked
observer for 8 of the tables I felt to be particularly pertinent (Vol.
12, Tables 26, 28, 34, 36, 46, 48, 55, 63). The results were presented
in Amendment 13. The statistical superiority of Artecoll was maintained
separately for each observer, in every place where it occurred when they
were pooled. Thus, the sponsor's conclusions are the same as would have
been inferred by use of any single masked observer.

*Relationships among Efficacy Measures*

The sponsor also performed a correlation analysis between the primary
efficacy endpoint (masked observer rating) and the two secondary study
objectives (investigator ratings of success (unmasked) and patient
ratings of satisfaction (masked)). The Spearman rank-order correlations
(Vol. 12, Table 59) are not impressive. Table 60 shows that there were
statistically significant differences between masked and unmasked
pretreatment FFA scores for all 4 treatment areas, with unmasked ratings
being about 1 point higher. This is more reason to consider only the
masked analysis, because the unmasked analysis could be biased.

A more relevant measure would be the agreement, or consistency among the
three masked observers. The sponsor's use of the intraclass correlation
coefficient as a measure of inter-rater reliability is appropriate given
that these are interval data. However, the coefficient actually measures
inter-rater "consistency", and not agreement, per se. If one rater rates
consistently higher or lower than another, and this pattern is
maintained across treatment groups, the intraclass correlation will be
high, even if the scores for a given wrinkle do not seem to agree. Since
interpretation of the FFA scale has an element of subjectivity in it,
consistency is sufficient for evaluating inter-rater reliability. The
intraclass correlation was about 90% for most treatment areas, which is
good.

*Bias from Smoking and Sun Exposure*

The question arose as to whether there could be biases in patient
enrollment from baseline differences in smoking and sun exposure.
Looking at the distribution of smoking in the table on page 1-069 of
Amendment 9, and the correlation coefficients given on page 1-070, I am
satisfied that smoking was not a source of potential bias. It appears
the sponsor used a 3 or 4 point ordinal scale for smoking and sun
exposure (e.g., 0-2, or 0-3) and then used the Mann-Whitney U-test. This
is the counterpart of the t-test for independent samples, and its use
here is acceptable. There was less sun exposure among the controls, and
the negative Spearman correlation with treatment outcome shows that
lower sun exposure is correlated with greater improvement from
treatment. Therefore, I would have to agree that, if anything, the bias
was in favor of the control group. To help control for differences in
sun exposure, I requested a subgroup analysis of just the low-exposure
group (49 Artecoll, 58 controls). The statistical superiority of
Artecoll remained, although the actual treatment difference was only
about ½ point on the FFA scale.

Mean Nasolabial Fold Masked FFA Scale Improvement at Six Months

\- Low Sun Exposure Group

  ------------------ ------- ------------- -------------- -----------------
  Treatment          N       Mean          Mann-Whitney   
                                           Test           

  Artecoll           49      0.64          U              p

  Control            58      0.15          913.0          0.001
  ------------------ ------- ------------- -------------- -----------------

*Categorical Analyses*

Because there were problems with pretreatment differences in wrinkle
severity, non-normal data and achieving a prespecified value for
clinical improvement, the sponsor also performed some categorical
analyses not subject to these conditions. The sponsor compared the
proportions of patients who had a pretreatment wrinkle severity rating
of at least "1", and improved at least 1 point on the masked observer
FFA scale at 6 months. As shown in the table below, a statistically
significantly higher percentage of Artecoll patients improved 1 point or
more in nasolabial fold severity as compared to the control (47.8%
(32/67) vs 13.2% (7/53)). The other treatment areas were not
statistically significant.

Percentage of subjects with pretreatment Masked Observer FFA Scale
ratings of at least 1.0 showing improvement of at least 1.0 points

+--------------+----+-------------+----+------------+---------+------+
| Treatment    | Ar |             | C  |            | Chi     | p-v  |
|              | te |             | on |            | -Square | alue |
| Area         | co |             | tr |            |         |      |
|              | ll |             | ol |            |         |      |
+--------------+----+-------------+----+------------+---------+------+
|              | N  | \%          | N  | \%         |         |      |
|              |    | Si          |    | Sig        |         |      |
|              |    | gnificantly |    | nificantly |         |      |
|              |    | Improved    |    | Improved   |         |      |
+--------------+----+-------------+----+------------+---------+------+
| Glabellar    | 46 | 28.3        | 48 | 33.3       | 0.095   | .757 |
| Folds        |    |             |    |            |         |      |
+--------------+----+-------------+----+------------+---------+------+
| Nasolabial   | 67 | 47.8        | 53 | 13.2       | 14.569  | \<   |
| Folds        |    |             |    |            |         | .001 |
+--------------+----+-------------+----+------------+---------+------+
| Upper Lip    | 31 | 12.9        | 27 | 7.4        | 0.064   | .800 |
| Lines        |    |             |    |            |         |      |
+--------------+----+-------------+----+------------+---------+------+
| Mouth        | 55 | 18.2        | 58 | 13.8       | 0.144   | .704 |
| Corners      |    |             |    |            |         |      |
+--------------+----+-------------+----+------------+---------+------+

Another subgroup analysis focused on those subjects who had a
pretreatment severity of at least "2" and improved at least 1 point
(Vol. 12, Table 66). For nasolabial folds, 71% (22/31) of the Artecoll
as opposed to 24% (6/25) of the controls met this criteria (p=0.001).
Thus, Artecoll appeared to work better than the control in a reasonably
high percentage of patients with moderate initial severity, although
these results are based on rather small numbers. This study population
was such that over 70% had pretreatment wrinkle severity scores less
than 2.0 for all treatment areas. Because the primary endpoint spelled
out in the protocol was statistically significant for nasolabial folds,
these additional subgroup analyses can be performed without being
considered exploratory data analysis.

*Safety*

As far as safety is concerned, I don\'t see a statistical difference
between the 2 treatment groups. There were more subjects who had adverse
effects with Artecoll (21 vs 16), but the controls tended to have
[multiple]{.underline} AE\'s per person (36 AE\'s for 16 controls versus
26 AE\'s for 21 Artecoll). The safety profile has been extensively
discussed in the clinical review.

*Summary*

In summary, the main weaknesses of this study, along with a brief
description of how each was addressed are summarized below.

-   Large differences between masked and unmasked FFA Scale ratings that
    suggest potential for bias in wrinkle assessment

    -   FDA statistical review focused on masked analyses only

-   For each wrinkle, scores averaged across multiple observers and two
    sides of the face

    -   Perform analyses stratified by masked observer

-   Use of parametric statistics when assumptions of normality are not
    met

    -   Perform additional nonparametric analyses

-   Enrolling patients that had, for the most part, mild defects that
    afforded little room for improvement

    -   Subgroup analysis of pretreatment wrinkle severity ≥1

    -   Small subgroup analysis of pretreatment wrinkle severity ≥2

-   Significant difference between Artecoll and control in masked
    [pretreatment]{.underline} severity for best performing area
    (nasolabial folds)

    -   Adjust for baseline differences in several ways

-   Abundance of timing violations for follow-up visits (⅓ to ½ of
    patients)

    -   Subgroup analysis of those meeting timing restrictions

-   A mean improvement (masked FFA Scale) for the best performing area
    (nasolabial folds) of 0.77, when the clinically meaningful
    improvement was predetermined to be 1.0

    -   Must be clinically assessed

*Conclusion*

In conclusion, I feel that, although the study has several weaknesses,
the highly significant result at 6 months for nasolabial folds holds up
even after adjustment of the significance level for multiple treatment
areas, and the effect was corroborated by additional categorical
analyses. Baseline differences in pretreatment severity, and other
potential sources of bias (e.g., attrition, follow-up timing, center
differences, smoking, sun exposure) have all been addressed by
statistical analyses and found not to have a significant impact.
Therefore, I find that the data to support a claim of statistical
superiority for nasolabial folds at 6-months post-treatment,
particularly for defects of moderate pretreatment severity. Whether this
difference is clinically significant will have to be addressed by
subject matter experts.