**CALL TO ORDER**

Panel Chair Michael Wilson, MD, called the meeting to order at 9:47 AM.
The Panel Executive Secretary Freddie Poole read the conflict of
interest statement and noted that wavers had been granted to Drs. Ng and
Nachamkin, which allowed their full participation in today's meeting.
Further, matters of past interest had been considered for Drs. Baron,
Carroll, Nolte, Reller and Sanders and their full participation was
allowed. Dr. Wilson then asked the panel members and consultants to
introduce themselves.

# NEW BUSINESS

PRESENTATION OF THE PREMARKET APPROVAL APPLICATION

**Sepsis Inc, Endotoxin Activity Assay (EAA)** P 0100226**.** *An in
vitro diagnostic device for the determination of endotoxin activity in
human blood samples, to rule out Gram negative infection.*

# SPONSOR'S PRESENTATION

**Paul Walker, MD, Ph.D.**, President & CEO, Sepsis Inc., introduced the
Endotoxin Activity Assay (EAA) and described the interactive review
process and presented the intended use, to rule out the presence of gram
negative organisms -- a shift in diagnostic paradigm strategies.

**R. Phillip Dellinger, MD**, a Site Investigator, Director, Critical
Care Medicine, Rush Presbyterian St. Luke's Medical Center, explained
the proposed use of EAA in the decision making process for infections in
the intensive care unit. In their pivotal study, the MEDIC Trial, 18% of
the patients had confirmed infection and 8% had gram negative infection.
He concluded that the because there is now general consensus that
endotoxemia occurs in absence of gram negative infection these findings
can be used with negative blood cultures to tailor patients' treatment.

**Alex Romaschin, Ph.D.**, Scientific Director, Sepsis Inc., and
Associate Professor of Laboratory Medicine and Surgery, University of
Toronto, described the technology of the chemo-luminescent assay. The
antibody used in this assay has high specificity and sensitivity to the
Lipid A molecule found in endotoxins. Gram positive bacteria, pathogenic
fungi and their cell walls or disruptive membrane products do not react
in this assay. Lipopolysaccharide binding proteins, which are
problematic in the LAL assays, did not confound this reaction. He
concluded that the unit dosage format of the assay, and the
reproducibility with which it could be performed, and that the assay is
completed in one hour, makes this assay a good indicator for the absence
of gram negative infection.

**Debra Foster. BSc**. Clinical Project Manager, Sepsis Inc., presented
the clinical investigative plan for the Multi-center Endotoxin Detection
in Critical Illness (MEDIC) Trial. Ten centers in four different
countries (US, Canada, Belgium and UK) participated in the study. The
inclusion criteria were all ICU patients suspected of having an
infection. These patients had at least one set of blood cultures and
were followed for seven days. The CDC criteria were initially used to
interpret gram negative infection. A clinical evaluation committee (CEC)
was later employed to adjudicate the interpretation of the data.

**John Marshall, MD**, Principal Investigator, Research Director
Medical-Surgical ICU, Toronto General Hospital, discussed the pivotal
trial in which 408 evaluable patients were enrolled from intensive care
units and tertiary care facilities. He further explained the necessity
of the CEC and the shortcomings of using only CDC interpretive criteria.
Eighteen per cent of the evaluable patients showed gram-negative growth
in their blood specimens. Thirteen percent met the CEC criteria and 8%
met the CDC criteria for infection. The specificity and sensitivity of
these tests were similar between the two criteria, roughly 33% and 80%
respectively. If the blood culture and the assay were drawn on the same
day and were negative, there was a 94% negative predictive value (NPV)
(likelihood that the patient did not have a gram negative infection)
with the CEC criteria and 91% NPV with the CDC criteria..

**Dr Paul Walker** summarized the presentation by noting Sepsis Inc. has
proposed EAA as an adjunct test with blood culture in ruling out gram
negative infection in patients admitted to the ICU, at risk of or
suspected of having an infection.

**Dr. Wilson** invited the panel members to question the sponsor. The
panel wanted to know the effect of polymorphonuclear leukocytes,
albumin, antibiotics, and corticosteroids and immunosuppression response
on the assay. The firm responded that there were no effects. Other
questions asked were: Did fungal infection and gram positive infection
lead to false positives? What would a clinician do differently with a
positive or negative assay? The sponsor responded that they were not
making claims for a positive EAA test result; however a negative test
would infer that the patient did not have a gram negative infection. How
much weight did this test have on its own merit? The firm responded that
it was an added piece if information. The negative predictive value was
based on an erroneous assumption that a negative culture meant that the
patient did not have infection. Another panel member commented that the
pretest probability was 83-87, or maybe 92, but with the EAA the
probability is 91 percent.

# FDA PRESENTATION

**Marian Heyliger, MS**, Senior Scientific Reviewer, Bacteriology
Devices Branch, presented an overview of the spectrum of sepsis and
laboratory diagnosis. She pointed out the differences in the false
negative rates using CDC and CEC criteria. The EAA sensitivity of 80%,
was based on gram negative infection, however, there was no evaluation
of false positive rates due to a lack of specificity of endotoxin
production. It is well documented that endotoxins arise from other
sources than gram negative infection. She stated that FDA would like to
know if the false-positive results should be included in the evaluation
of the assay. She described the organisms isolated and the various sites
of infection in the false negative population. She noted EAA is limited
by non-hematogenous and remote sites of infection, and false positive
bacterial cultures due to colonization. In closing, she raised two
questions: 1) could infection outcomes be better measured beyond Day 1
and 2) does the negative predictive value (NPV) of 91% and 94%, as found
in this study, indicate a role for this assay in clinical laboratory
diagnosis?

**John Dawson, MS, JD**, Mathematical Statistician, Division of
Bio-statistics, Office of Surveillance and Biometrics, presented the
FDA's statistical perspective on the application. He explained that
negative predictive value (NPV) requires a gold standard for unbiased
evaluations. When there is no gold standard, NPV stands on its own.
Since the NPV takes prevalence into account, it is more accurate to
interpret negative predictive value as a probability, that is,
probability a patient would have a negative test, if he had been in the
study.

**Dr. Wilson** then invited the panel to ask questions of the FDA. The
panel had questions concerning the validity of the confidence level in
such a small study, the meaning of a negative culture, the threshold
level between positive and negative cases, the composition of ICU
patients that is, proportion of medical and surgical patients and
species bias, (did EAA miss Serratia, Pseudomonas and E. coli?) Other
concerns expressed were the EAA 0.4 cutoff vs. 0.3; and criteria used by
the CEC.

# OPEN PUBLIC HEARING

Dr. Wilson opened the meeting for comments from the public. There were
no comments from the public. The Open Public Hearing session was then
closed.

# FDA Questions

**Question #1: The performance parameters used to describe this assay
included sensitivity, specificity, positive predictive value (PPV) and
negative predictive value (NPV). Are the diagnostic endpoints used in
these calculations (CDC criteria and Clinical Evaluation Criteria)
appropriate to support these terms or should alternative descriptive
terms (% agreement, etc) be used?**

**Dr. Nachamkin** felt that there was no compelling evidence presented
with this limited data for the ability of the test to rule out
infection. A report of endotoxin present, is not a safe method of
reporting an assay. He believes that the sponsor might not have taken
the clinician decision making into account. **Dr. Charache** thought
that the values are expressed as predictive values and are stated as
predictive of infection, when in fact there is no documentation that it
is. If you look at percent agreement then you have to add all your false
positives and false negatives. If the goal of the test is to get a no
answer then you should look only at the negative tests. **Dr.**
**Nolte** wondered how the difference in CDC and CEC data influenced the
clinical outcome. He didn't think there is any choice but not to use
conventional parameters of sensitivity and specificity. **Dr. Durak**
suggested that FDA consider using a quasi-gold standard. **Dr. Reller**
stated that the test did not give sufficient confidence to dictate
appropriate clinical action. **Dr. Solomkin** advised the sponsor to
look at each gram-negative infection on a site by site basis, since
infections such as meningitis would probably have low levels of
endotoxin, whereas a gram-negative pneumonia infection would have high
levels of endotoxins.

**Question #2:** **The sponsor stated that the NPV is the key parameter
in the EAA assay. Is the NPV of 91% (84 to 96% Cl) adequate and
acceptable for this assay? Is the PPV of 15% (11 to 20% Cl) adequate and
acceptable for this assay? Consider: 1) the use of the device and how it
affects patient management and treatment decisions, and 2) the varying
prevalence of gram negative infection in different ICU populations.**

**Dr. Baron** thought the sponsor should re-look at the threshold of
positivity and apply the larger pool of results to the ROC, which might
improve the NPV. **Dr. Nachamkin** was not comfortable with the wide
confidence interval for the negative predictive value, and thinks the
negative predictive value is an unacceptable test for predicting
infection. **Dr. Charache** worried about a test that missed 25% of the
true culture positive patients.

**Question #3:** **The primary outcome of the MEDIC Study was the
documentation of gram negative infection. The difficulty of determining
gram negative infection was shown by the implementation of a Clinical
Evaluation Committee (CEC) to provide a second evaluation of a patient's
infection status. Should device performance be evaluated using the CDC
criteria, the CEC criteria or both? Is use of clinical and laboratory
information from Day 1 of the study an appropriate endpoint to
characterize performance?**

**Dr. Wilson** asked the panel to focus on the second part of the
question since the first part had already been discussed. **Dr.**
**Durak** commented that it was important to distinguish clinical value
and performance, since they may not be the same. **Dr. Baron** wanted to
know what happened to the endotoxin levels on Day 2 and Day 3, so that
the clinician could make an informed decision. **Dr. Nolte** asked about
the interval for using the test. Would the test be used on admission and
then daily? **Dr. Danner** wanted to know about repeat testing; how many
tests have to be done before one positive test result is obtained
because endotoxemia may be intermittent. There may not be any
performance criteria that could describe this in the labeling.

**Question #4:** **Did the endotoxin assay meet the primary objective of
the MEDIC Study, to exclude the diagnosis of gram negative infection in
critically ill patients admitted to the ICU with suspected infection?
Consider: 1) The bio-availability of endotoxin in the setting of gram
negative sepsis. Some organisms shed more endotoxin than others; 2)
Binding of proteins to liposaccharide (LPS) and clearance of endotoxin
from the circulation; and 3) Limitations in the device's ability to
detect endotoxin from non-hematogenous infection sites early in the
course of infection.**

**Dr. Baron** reiterated that the study had ten false negative patients,
and only 33 that were excluded. This did not appear to meet the primary
objective..

**Question #5:** **What recommendations and suggestions should be
provided to improve the labeling of this assay?**

**Dr. Nachamkin** stated that the package insert should include the fact
that only one company supplied all the tubes for this test, therefore
any other tube should be evaluated before use. **Dr. Durak** thought
antibiotics and other drugs such as aspirin and cardio-active drugs,
which could possible be interfering substances, should be added to the
list in the labeling. **Dr. Baron** stated that since EAA works better
with sepsis than pneumonia, the labeling could list which types of
infectious diseases EAA rules out. **Dr. Nachimkin** disagreed, and
stated that because the numbers are so small, no generalizations can be
made about the type of infection. **Dr. Reller** suggested that we defer
this question until one had a product to label.

# OPEN PUBLIC HEARING

Dr. Wilson opened the Open Public Hearing session. No one came forward
to speak. He therefore closed the session.

# SPONSOR RESPONSE

**Dr. Dellinger** noted that using a panel of experts to decide if a
patient was infected provided the best possible predictability. **Dr.
Romaschin** stated that the overall precision found in the trial study
was 11% for all centers weighted by the number of patients. **Dr.
Romaschin** added that fluctuations in endotoxin were not observed over
time with extensive repeat tests. Dr. Walker stated that Sepsis Inc. has
not found a drug that interferes with this assay.

# FDA RESPONSE

The FDA had no further comments.

# VOTE AND RECOMMENDATIONS

The Executive Secretary **Freddie Poole** read the names of the voting
and temporary voting members. She then explained the voting options for
premarket approval that the panel could recommend. A motion was made and
seconded, and the Panel voted that the PMA was not approvable.

VOTE: The panel voted unanimously for not approval of the PMA. The panel
provided the reasons for their vote. Comments related to numbers being
too small in the study, no clinical role for the test, and possible use
in the research setting.

The panel then provided suggestions as to how the sponsor could make the
device approvable. They recommended that the sponsor should consider
increasing the sample size, which should increase the confidence in the
negative results. The test as it was had no clinical role in clinical
management. The study design should be revised to obtain meaningful
outcomes irrespective of differences between patients, sites and
personal characteristics. Endotoxemia does not equate with infection.
The false positives may provide further information on what the test is
detecting. The gold standard issue and the negative predictive value
must be resolved.

**Dr. Wilson** thanked the panel members for their participation and the
sponsor for its presentation

**Dr. Wilson** adjourned the meeting at 3:37 PM.