fda neuropace panel presentation (2-21) final · deaths 35 study days implanted days of stimulation...
TRANSCRIPT
1
FDA Introduction
Kristen A. Bowsher, Ph.D.FDA/CDRH/ODE/DNPMD
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
2
P100026 FDA Review Team• Kristen Bowsher, Ph.D. - Engineering• Ann Costello, Ph.D., D.M.D. – Clinical• Molly Ghosh, Ph.D. - Toxicology• Joseph Jorgens, D.Sc. – Software• Wolfgang Kainz, Ph.D. - MRI• Scott Miller, Ph.D. – Statistical• Lawrence Rodichok, M.D. - Clinical • Myra Smith, MS – Team Leader/Microbiology• Federico Soldani, M.D., S.M., Ph.D. - Postmarket• Donald Witters, Ph.D. & Joshua Guag – EMC/EMI
3
• Clinical Trial for RNS® System for Epilepsy (IDE G030126)
• NeuroPace, Inc. premarket approval application (PMA) (P100026)
» Safety and Effectiveness Data
• Panel Input and Recommendations
Purpose of Meeting
4
• Introduction• Device Description
» Kristen Bowsher, Ph.D.• Clinical Background, Study Overview, and Safety Data
» Lawrence Rodichok, M.D.• Effectiveness Data
» Ann Costello, Ph.D., D.M.D• Statistical Summary
» Scott Miller, Ph.D.• Post-Approval Study Considerations
» Federico Soldani, M.D., S.M., Ph.D.• Summation
» Lawrence Rodichok, M.D.
FDA Presentation Outline
5
NeuroPace RNS® System
Implanted Components
6
• Primary external components include a clinician programmer and a patient remote monitor
• Detection Algorithm» 3 Detection Tools (area, line-length, & bandpass)
• Stimulation Output Settings
• Adequate data not provided for MRI compatibility
NeuroPace RNS® System
7
FDA Overview of Epilepsy
Lawrence Rodichok, M.D.CDRH/ODE/DNPMD
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
7
8
Clinical Features of Partial Epilepsy
• Mesial temporal origin» Typical clinical features» 5-15 seizures per month» Other diagnostic studies consistent with
mesial temporal focus• Extra-temporal origin
» Clinical features differ» Many seizures per day» Localization can be difficult
8
9
Treatment Options
•Pharmacologic:» 60-70% with sustained seizure freedom for one year
or more» 12-25% difference between active and placebo
Median reduction in seizure frequency, and50% responder rate
» 1.5-3.6% likelihood of seizure freedom with new drug•VNS
» 13 to 17% difference in mean reduction with active compared to “low” stimulation
9
10
Consequences of Poorly Controlled Epilepsy
• Overall increased mortality• Increased SUDEP rates• Injuries
» Head injury in 2.7% of seizures» Subdural or epidural hemorrhage in 1 per
15,000 seizures
Russell-Jones and Shorvon, 1989
10
11
SUDEP• Generally accepted criteria
» Deaths reviewed by qualified committee in NeuroPace trials
• SUDEP rates per 1000 patient-years » 6 – 9: surgical candidates» 1 – 3: AED trials
• Risk reduced by effective treatment
11
12
FDA Overview of Clinical Studies
Lawrence Rodichok, M.D.CDRH/ODE/DNPMD
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
12
13
Overview of NeuroPace Studies
• Feasibility study• Pivotal study
» Blinded phase» Open label phase
• Long term treatment (LTT)
13
14
Feasibility Study
• Inclusion/exclusion criteria comparable to pivotal• First 4 subjects per site open label
» Then randomize 1:1» 70 enrolled» 65 subjects implanted» 42 open label; 23 randomized
• Stimulation start within 28 days• Effectiveness period: last 84 days• Responder rate >13% adequate to justify pivotal
trial14
15
Feasibility Study Results
• Safety» SAE to 1 month: 6.2% (upper CB 14.8%)» SAE to month 3: 9.2% (upper CB 18.7%)
• Responder rate» Open (N=42): 27%» Open+Active (N=51): 24%» Sham (N=14): 36%
• All groups met pre-specified futility assessment to proceed to pivotal trial
15
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Pivotal Study
• Double blind, randomized, multicenter trial• Inactive sham• Changes from feasibility
» 3 seizures per month; sensory excluded» Post-implantation stabilization – 28 days» Stimulation optimization period – 28 days» Blinded evaluation period – 84 days
16
17
Sample Size
• Sample size based on 50% responder rate: responder rate in the treated group of 40%, a rate of 20% in the sham group for a difference of 20%.
• Minimum 180 subjects to complete Blinded Evaluation Period (BEP)
17
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Key Inclusion Criteria
• Diagnostic testing localized no more than two epileptogenic regions» No specifed types or concordance of studies
18
19
Key Exclusion Criteria
• Non-epileptic seizure like events• Status epilepticus (SE) in the preceding year• Primary generalized epilepsy• Active psychosis, major depression or
suicidal ideation in the last year• Active Vagus Nerve Stimulation (VNS)• Need for MRI scan
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Study Periods
Baseline Period
Post-operative
Stabilization Period
Stimulation Optimization
Period
Blinded Evaluation
Period (BEP)
Open Label Period
84 days 28 days 28 days 84 days 84 weeks
Implantation Randomization
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Implantation• Up to 4 leads; no more than 2 depth leads• No specified criteria for placement• No specified criteria for modification of
detection parameters• Sensitivity and specificity of detection
algorithm during the trial not reported• No specific directions for modification of
initial programming parametersPanel Questions 4b & 4c
21
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Disposition of Subjects(June 4, 2010)
• 240 patients enrolled• 191 subjects implanted and randomized
» One death (sham)» One withdrawal (treatment)
• 187 of 189 completed end of Blinded Evaluation Phase (BEP)
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Baseline Clinical Characteristics
Balanced for» Age (years): 34.9 ± 11.6 (18 - 66)» Gender: 48% female» Epilepsy duration (years): 20.5 ± 11.6 (2 - 57) » Number of AEDs: 2.8 ± 1.2 (0 - 8)
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Baseline Seizure Frequencyper Month
Treatment Sham
N Mean Median(Min - Max) N Mean Median
(Min - Max)
BaselinePeriod 97 33.5 8.7
(3.0 - 294.7) 94 34.9 11.6(3.0 - 338.0)
2424
25
Subsets of Interest
1 p-value per chi-square2 Characteristics used as strata in adaptive randomization algorithm
CharacteristicsAll Implanted
(N = 191)
By Randomization Group
Treatment(N = 97)
Sham(N = 94) P-value1
Mesial Temporal Lobe Only (v. other)2 50% 49% 50% 0.943
Bifocal (v. unifocal)2 55% 49% 62% 0.089Prior therapeutic surgery for epilepsy2 32% 35% 30% 0.437
Prior EEG monitoring with intracranial electrodes 59% 65% 53% 0.098
Prior VNS 34% 31% 36% 0.443Anatomical brain abnormality 67% 68% 66% 0.759
Benzodiazepine use (acute) 36% 31% 41% 0.129
25
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Baseline Seizure Frequency by Subgroup
% ofSubjects
Pre-Implant Seizure Frequency
(Mean ± SD, seizures/month)Seizure Onset ZoneMesial Temporal Lobe 50% 15.8 ± 26.8Other 50% 52.4 ± 79.3
Number of Seizure FociUnifocal onset 45% 53.8 ± 84.7Bifocal onset 55% 18.5 ± 25.3
Prior Therapeutic Surgery for EpilepsyPrior Surgery 32% 56.4 ± 85.3No Prior Surgery 68% 23.5 ± 43.2
26
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Leads ImplantedAll Implanted
(N = 191)
By Randomization GroupTreatment
(N = 97)Sham
(N = 94)Number of Leads: % of Subjects
1 0% 0% 0%2 58% 57% 59%3 14% 14% 13%4 29% 29% 29%
Types of Leads: % of SubjectsCortical Strip Leads Only 31% 31% 31%Depth Leads Only 39% 37% 40%Cortical Strip and Depth Leads 30% 32% 29%
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FDA Overview of Safety Results
Lawrence Rodichok, M.D.CDRH/ODE/DNPMD
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
2828
Primary Safety Endpoint
Proportion of subjects with a Serious Adverse Event (SAE) during:
» acute post-implantation – 28 daysUpper Confidence Bound (CB) not to exceed 20%*
» short term chronic post-implantation – 12 weeks
Upper CB not to exceed 42%*
29
* see references in executive summary
29
Primary Safety Endpoint
Pivotal %[upper CB]
Pooled %[upper CB]
Comparator %[upper CB]
Acute(Surgery-Week 4)
12.0% [16.5%]
10.5%[14.9%]
15%[20%]
Short-term Chronic(Surgery-Week 12)
18.3%[23.4%]
16.0%[21%]
36%[42%]
3030
Adverse EventsImplantation to 20 Weeks
% of subjects reporting ≥ 1 AE, Implant through BEP2 (20 Weeks)
Treatment(N=97)
Sham(N=94) P-Value1
Serious AEs 16.5% 23.4% 0.377
Non-Serious ("Mild") AEs 92.8% 89.4% 0.917
Total AEs 92.8% 93.6%1 Comparison of percentage of subjects with AEs, Treatment vs. Sham, per Fisher's exact test2 Blinded Evaluation Period
3131
SAEs by Study Period
Study PhaseStudy Time
Period(weeks)
Treatment Group% (subjects)
[#events]
Sham Group% (subjects)
[#events]Post-operative Stabilization 0-4 12% (23/191)
[27]Stimulus Optimization 4-8 6.2% (6/97)
[10]6.4% (6/94)
[7]Blinded Evaluation 8-20 4.2% (4/96)
[4]5.4% (5/93)
[7]
Total 0-20 16.5% (16/97) 23.4% (22/94)
3232
SAEs During Post-operative Stabilization
• Implant site – 7» 5 infections» 1 sub-galeal effusion» 1 discharge
• Intracranial hemorrhages – 4» Extradural: 2» Subdural: 1» Intraparenchymal: 1
Panel Question 1a3333
SAEs by study period
34
Study PhaseStudy Time
Period(weeks)
Treatment Group
% subjects[#events]
Sham Group% subjects[#events]
Post-operative stabilization 0-4 12% (23/191)
[27]
Stimulus optimization 4-8 6.2% (6/97)
[10]6.4% (6/94)
[7]Blinded Evaluation 8-20 4.2% (4/96)
[4]5.4% (5/93)
[7]
Total 0-20 16.5% (16/97) 23.4% (22/94)
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Deaths
35
StudyDays
ImplantedDays of
StimulationSUDEP / Cause of
Death as AdjudicatedStimulation Status at
Time of Death
Feasibility 473 361 Definite SUDEP Enabled
Pivotal 594 450 Possible SUDEP Enabled
Pivotal 36 0 Possible SUDEP Disabled
Pivotal 351 323 Definite SUDEP Enabled
Pivotal 324 295 Definite SUDEP Enabled
Pivotal 230 25 Suicide Enabled
Pivotal 371 344 Lymphoma Enabled
LTT 856 459 Definite SUDEP Disabled
LTT 1139 533 Suicide Disabled
LTT 1295 1147 Status epilepticus Enabled
LTT 1276 1129 Probable SUDEP Enabled
Panel Question 1b 35
SUDEP
* (Leetsma et al., 1997); ** (Ryvlin et al., 2011); *** (Dasheiff, 1991)
36
RNS® System Trials Population SUDEP Rate(per 1,000 implant years)
As of June 4, 2010 8.5 [95% CI: 3.8 – 18.9]
As of October 24, 2012 6.6 [95% CI: 3.0 – 14.8]
Medically Refractory Populations SUDEP Rate(per 1,000 patient years)
Candidates for AED trials * 3.5
Meta-analysis of AED trials ** 6.9 [95% CI: 3.8 – 11.6]
Candidates for epilepsy surgery *** 9.3
Panel Question 1b36
Pooled Safety Population
• All implanted who are or were participating in RNS studies as of submission cut-off date (June 4, 2010)» 59 feasibility subjects completed» 98 pivotal subjects had completed
• 256 subjects over 708.1 implant years and 632.3 patient stimulation years
3737
Safety at One YearPooled Safety Population (N=256)
SAEs in 34.0%» 161 events in 87 subjects» Most common: % of population [# of events]
Complex partial seizures increased: 4.7% [13]Implant site infection 2.3% [7]EEG monitoring: 2.3% [6]Tonic clonic seizures increased: 2.0% [6]Tonic clonic seizures exacerbated: 2.0% [5]Device lead damage: 2.0% [5]
38Panel Question 1b
38
Intracranial HemorrhagesPooled Safety Population (N=256)
39
Adverse Event
All Adverse Events(Serious and Non-
Serious)
SeriousAdverse Events
Preferred Term
% Subjects with events(# subjects)
# Events% Subjects with SAEs
(# subjects)# SAEs
Summary of all intracranial hemorrhage and hematoma events 5.1% (13) 13 4.3% (11) 11
Cerebral haemorrhage 2.0% (5) 5 1.6% (4) 4
Extradural haematoma 1.2% (3) 3 0.8% (2) 2
Subdural haematoma (dts*) 1.2% (3) 3 1.2% (3) 3
Subdural haematoma 0.4% (1) 1 0.4% (1) 1
Traumatic intracranial haemorrhage (dts*) 0.4% (1) 1 0.4% (1) 1
* dts = due to seizuresData as of June 4, 2010. Panel Question 1b 39
InfectionsPooled Safety Population (N=256)
40
Adverse Event All Adverse Events(Serious and Mild)
SeriousAdverse Events
Preferred Term
% Subjects with events
(# subjects)# Events
% Subjects with SAEs (#
subjects)# SAEs
Summary of all implant or incision site infections 8.6% (22) 26 5.9% (15) 17
Implant site infection 5.5% (14) 16 4.7% (12) 14
Incision site infection 2.7% (7) 8 0.4% (1) 1
Implant site infection (dts*) 0.8% (2) 2 0.8% (2) 2
* dts = due to seizuresData as of June 4, 2010. Panel Question 1b 40
Other SAEs of Special InterestPooled Safety Population (N=256)
41
SAE Group
Serious Adverse Events% Subjects with
SAEs(# subjects)
# SAEs
Changes in seizures 14.8% (38) 64Seizure-related injury 8.2% (21) 28 Psychiatric 7.4% (19) 30Status epilepticus 3.5% (9) 17
Panel Question 1b41
Changes in SeizuresPooled Safety Population (N=256)
42
New Increased Exacerbated% subjects[# events]
% subjects[# events]
% subjects[# events]
Simple partial motor - 1.6% [9] 0.4% [1]
Complex partial 0.4% [1] 6.3% [18] 1.2% [3]
Generalized tonic clonic 0.4% [1] 5.9% [19] 3.5% [9]
Panel Question 1b42
Seizure Related InjuriesPooled Safety Population (N=256)
• Non-serious:46.1%» Serious 8.2%
• Contusion: 16%» 0.4% serious
• Skin laceration: 16.0%» 2.0% serious
• Head injury: 9.0%» 0.8% serious
43Panel Question 1b 43
Psychiatric Adverse EventsPooled Safety Population (N=256)
• 15 SAEs in 10 subjects related to suicidality• 2 completed suicides• 4 events of an acute psychosis in 2 subjects
44Panel Question 1b
44
Status EpilepticusPooled Safety Population (N=256)
• 18 events; 3.9% of subjects» 17 in 9 subjects serious
• One subject with 9 episodes
4545
Safety Conclusions• Peri-procedural complication rate
» Met pre-specified upper bound» No worse than the risks of other implantations
in brain• No apparent risk of neurostimulation• Long term safety
» Compatible with poorly controlled epilepsy» Concern for intracranial hemorrhage due to
seizure/injury and seizure related injuries
Panel Questions 1a-c, 44646
FDA Effectiveness Presentation
Ann Costello Ph.D., D.M.D.FDA/CDRH/DNPMD
47
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
Prespecified Primary Effectiveness Endpoint
• Demonstrate superiority of the Treatment group over the Sham group in reducing the frequency of total disabling seizures during the BEP.
• Modeled seizure count data using generalized estimating equations (GEE) model
48
Adaptive Randomization• Used to balance variables that might influence the
clinical response
• Variables (listed in order of priority) » Investigational site» Seizure onset zone location » Number of seizure foci» Previous resection
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Mean, Median and Range of Seizures during Baseline and Blinded Evaluation Period (BEP)
Treatment Sham
N MeanMedian
(Min - Max) N MeanMedian
(Min - Max)
BaselinePeriod 97 33.5 8.7
(3.0 – 294.7) 94 34.9 11.6(3.0 – 338.0)
BEP 96 22.4 5.8(0 – 247.0) 93 29.9 7.6
(0 – 799.0)
Difference 11.5 2.7 5.0 4.6
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Range of Seizures per Month
51
Range of Seizures per Month
52
Observed Mean Seizure Counts
Panel Question 2
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
53
Baseline Post-op Blinded Evaluation Period
Observed Mean Seizure Counts
Panel Question 2
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
54
Baseline Post-op Blinded Evaluation Period
Observed Mean Seizure Counts
Panel Question 2
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
55
Baseline Post-op Blinded Evaluation Period
StimulationON
Observed Mean Seizure Counts
Panel Question 2
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
56
Baseline Post-op Blinded Evaluation Period
StimulationON
Observed Mean & Median Seizure Counts
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
Mean
Median
57
Baseline Post-op Blinded Evaluation Period
Observed Mean & Median Seizure Counts
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
Mean
Median
58
Baseline Post-op Blinded Evaluation Period
SurgicalEffect
Observed Mean & Median Seizure Counts
Months0-1 1-2 2-3 0-1 1-2 2-3 3-4 4-5
Mean
Median
59
Baseline Post-op Blinded Evaluation Period
SurgicalEffect
Primary Effectiveness AnalysisPrespecified Generalized Estimating Equations
(GEE) Model• Daily seizure counts• Poisson distribution• Compare 84 days of the baseline period to 84 days
of the BEP • Two standard error estimation methods: empirical
and model-based• Model-based p <0.0001• Empirical p = 0.15
Panel Question 260
Discussion of Effectiveness EndpointNeuroPace and FDA
• Discussion followed unblinding of the data and analysis of the prespecified primary effectiveness endpoint
• Agreements» Difference in p-values indicated poor fit of the model to the
data» Alternative analysis model needed » Both the pre-specified and alternative analysis models
could be provided in PMA61
NeuroPace’s Post-hoc Effectiveness Analysis
• Daily → Monthly seizure counts• Poisson → Negative binomial distribution • Add the clinical covariates
» Seizure onset» Number of seizure foci» Prior resective surgery
62
NeuroPace’s Post-hoc GEE Model
Percent Change from Pre-Implant Period [95% confidence interval]
Treatment -37.9%[-46.7%, -27.7%]
Sham -17.3%[-29.9%, -2.3%]
Difference -20.6%
63
Model-based p-value = 0.0056Empirical p-value = 0.012
Uncertainties with Post-hoc Primary Effectiveness Analysis
• Prespecified effectiveness endpoint: » Model-based: p<0.0001 » Empirical: p=0.15
• Post-hoc effectiveness endpoint:» Model-based: p=0.056» Empirical: p=0.012
• Some alternative post-hoc GEE models do not achieve statistical significance.
• None of the prespecified secondary endpoints achieve statistical significance
• No observed data analyses achieve statistical significance64Panel Question 2
Prespecified Secondary Effectiveness Endpoints
• Responder analysis (50% reduction from baseline)
• Change in mean seizure frequency• Proportion of seizure-free days• Self-reported seizure severity according to the
Liverpool Seizure Severity Scale inventory
65
Secondary Effectiveness Endpoint Results
The study was powered on the expectation of a 20 % difference inresponder rates between the treatment and sham groups.
No interim analysis was performed.
Effectiveness Endpoint Treatment Sham P-value
50% Responder Rate 29% 27% 0.727
% Change in Mean Seizure Frequency -24% -17% 0.238
% Change in Days with Seizures -18.9% -18.3%Not
Reported
Liverpool Seizure Severity Score -4.7 -5.8 0.574
Panel Questions 2 & 3a(i)66
Post-hoc AnalysisMonthly Responder Rates
BEPTreatment
% Responders(n/N*)
Sham% Responders
(n/N*)Difference P-value
Expected 40% 20% 20%
Entire BEP 29% (28/96) 27% (25/93) 2% 0.727
Month 2-3 34% (33/96) 39% (36/93) - 5% 0.536
Month 3-4 39% (37/95) 31% (28/90) 8% 0.264
Month 4-5 34% (32/95) 30% (27/91) 4% 0.557* N represents the number of subjects for which any seizure data are
available for that time period.
67
Observed Median Percent Changein Seizures
Effectiveness Endpoint Treatment Sham Difference
% Median Change in Seizures - 28% - 19% - 9%
Panel Question 3a(i)68
Percent of Subjects with Increase or Decrease in Seizure Counts during BEP
Seizures
TreatmentN=96
% Subjects(#subjects)
ShamN=93
% Subjects(#subjects)
Difference
No change or increase 24% (23) 30% (28) - 6%
> 0 to < 50% reduction 47% (45) 43% (40) 4%
≥ 50% reduction 29% (28) 27% (25) 2%
> 90% reduction 5% (5) 4% (4) 1%
69
Prespecifed Additional Study Measures
• Subset analyses of clinical covariates » Seizure onset zone » Number of seizure foci» Prior resective surgery
• Quality of Life in Epilepsy (QOLIE)-89
70
Seizure Onset ZoneResponder Rates
Treatment Sham Difference(Treatment – Sham)
Mesial Temporal Onset (N=95)
Responders 33% (16/48) 26% (12/47) 7%
Other Onset (N=96)
Responders 24% (12/49) 28% (13/47) - 4%
Panel Question 3a(ii)71
Seizure FociResponder Rates
Treatment Sham Difference(Treatment – Sham)
One Seizure Focus (N=85)Responders 31 % (15/49) 28% (10/36) 3%
Two Foci (N=106)
Responders 27% (13/48) 26% (15/58) 1%
72Panel Question 3a(ii)
Prior SurgeryResponder Rates
Treatment Sham Difference(Treatment – Sham)
No Prior Resection (N= 129)Responders 32% (20/63) 26% (17/66) 6%
Prior Resection (N= 62)Responders 24% (8/34) 29% (8/28) -5%
73Panel Question 3a(ii)
QOLIE-89Proportion of subjects with > 5 point improvement
Treatment Sham P-value
QOLIE-89 Overall Score 36.6% (34/93) 39.1% (34/87) 0.760
1 Year 2 Years
QOLIE-89 Overall Score 38% (63/166) 44% (68/154)
Panel Question 3a(i)74
Seizure SubtypesResponder Rates
Seizure TypeTreatment
(N=96)Sham(N=93)
Difference(Treatment – Sham)
SimplePartial- motor 55% (11/20) 29% (6/21) 26%
Complex Partial 31% (26/83) 38% (31/81) - 7%
Generalized Tonic-clonic 46% (19/41) 33% (14/42) 13%
Total Disabling 29% (28/96) 27% (25/93) 2%
75Panel Question 3a(ii)
Sham Group Observed Mean Seizure Counts (Baseline through month 9)
Baseline 0-1 4-53-42-31-2 8-97-86-75-6
76
Months Post-opPost-op Blinded Evaluation
PeriodOpen Label Months 5 - 9
Panel Question 3b
Sham Group Observed Mean Seizure Counts (Baseline through month 9)
Baseline 0-1 4-53-42-31-2 8-97-86-75-6
77
Months Post-opPost-op Blinded Evaluation
PeriodOpen Label Months 5 - 9
Panel Question 3b
Sham Group Observed Mean Seizure Counts (Baseline through month 9)
Baseline 0-1 4-53-42-31-2 8-97-86-75-6
78
Months Post-opPost-op Blinded Evaluation
PeriodOpen Label Months 5 - 9
Panel Question 3b
Baseline 0-1 4-53-42-31-2 8-97-86-75-6
79
StimulationON
Months Post-opPost-op Blinded Evaluation
PeriodOpen Label Months 5 - 9
Panel Question 3b
Sham Group Observed Mean Seizure Counts (Baseline through month 9)
Observed Mean Seizure Counts in Sham Comparison of Months 6 to 9 to Baseline and BEP
Time Period
Mean Seizure Frequency
Months 6-9 to Baseline(N = 91)
Month 6-9 to BEP(N = 91)
Change - 7.8 - 2.5
p-value 0.04 0.39
80
Sham subjects receive stimulation for the first time at month 5.
Open Label DataObserved Mean Seizure Frequency Over Time with 95% Confidence Intervals
81
Baseline BEP 5-8 8-11 11-14
20-2317-2014-17 23-26
Open Label Panel Question 3b
Open Label DataObserved Mean Seizure Frequency Over Time with 95% Confidence Intervals
82
Baseline BEP 5-8 8-11 11-14
20-2317-2014-17 23-26
Stimulation ON
Open Label Panel Question 3b
Open Label DataObserved Mean Seizure Frequency Over Time with 95% Confidence Intervals
83
Baseline BEP 5-8 8-11 11-14
20-2317-2014-17 23-26
Stimulation ON
Stimulation ON
Open Label Panel Question 3b
Open Label DataObserved Mean Seizure Frequency Over Time with 95% Confidence Intervals
84
Baseline BEP 5-8 8-11 11-14
20-2317-2014-17 23-26
Stimulation ON
Stimulation ON
Open Label Panel Question 3b
Concerns with Open Label Data
• Subjects know they are receiving stimulation which may cause them to overestimate the benefit
• Regression to the mean• Changes to AEDs• Missing data/drop outs
85Panel Question 3b
AED Changes in Open Label Period (N=183)
AED Change % Subjects (N)Decrease 7.7% (14)Increase 21.9% (40)Increase and Decrease 16.4% (30)No change 54.1% (99)
Panel Question 3b86
All subjects continue to take AEDs.
Subject Discontinuations (43/256)• 8 Infection or Hemorrhage• 9 Deaths • 3 Lost to Follow-up• 23 Elective
» 14 Pursue other treatments» 4 Reduction in seizures not sufficient » 3 Not wish to undergo IPG replacement » 1 withdrawn because of psychiatric issues » 1 reason for withdrawal not specified.
87
FDA Statistical Presentation
Scott W. Miller, Ph.D.FDA/CDRH/OSB/DBS
88
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
Outline• Overview of trial• GEE model
» What is it measuring?» Improvement metrics
• 3 sources of uncertainty:1. Alternative GEE models2. Differential response by baseline seizure
count3. Influential Sham subjects
• Statistical conclusions89
Overview of Clinical Trial• 2 arm, randomized (1:1) concurrent sham-control
double-blind clinical trial• Sample size based on secondary outcome
» 50% responder rate in seizure count from baseline• Primary effectiveness endpoint
» Seizure counts over 3 months of baseline and 3 months of blinded evaluation
• Primary effectiveness analysis» Generalized Estimating Equations (GEE) for
longitudinal count dataAnalyzes mean seizure counts over time on the same subjects
90
Overall Mean Number of Seizures
Phase MonthTreatment
(N=97)Sham(N=94)
Seizures per Month
Baseline (BL)
-3 34.5 28.7-2 34.3 34.5-1 31.7 41.5
Blinded Evaluation
Period (BEP)
2-3 22.9 27.13-4 22.8 28.9
4-5 21.4 35.4
91
92
GEE Model – What is it measuring?
92
9393
GEE Model – What is it measuring?
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GEE Model – Difference in Slope
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Time
Group*Time
GEE Model: Standard ErrorsTwo standard error estimation methods:• Model-based
» Assumes variance of model correctly specified• Empirical / robust
» Calibrates model-based estimate with variance observed in the data
» Robust to mis-specification of variance of model» Potentially less efficient in some settings
• Two methods can give different results» Different results sometimes indicate poor model fit
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Study Results
• The GEE model estimates the mean seizure counts in the BEP relative to baseline
• Ratio of seizure frequency: BEP to baseline (BL)*» Treatment: 62.1% of BL level (37.9% reduction from BL)» Sham: 82.7% of BL level (17.3% reduction from BL)
• Relative rate ratio (RR) of Treatment to Sham: » 62.1/82.7 = 75%
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* Numbers from Table 41 of FDA Executive Summary
3 Sources of Uncertainty
1. Alternative GEE models
2. Differential response by baseline seizure count
3. Influential Sham subjects
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1. Multiple Plausible GEE Models:
Panel Question 2Model-based estimateEmpirical estimate
2. Differential response by baseline seizure count:
• Does response to treatment vary by baseline seizure count?
• Statistical test of interaction» Inference on interaction terms known to have lower
power than main effects» Interactions typically need to be visualized to see
what the issue is• Grouped baseline into 4 categories by 3 cutoffs:
» 0-1 seizure per day at baseline, 1-2, 2-3, >3» Goal is descriptive, not formal statistical claim
9999
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2. Differential response by baseline seizure count:
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2. Differential response by baseline seizure count:
S: N=69T: N=71
Panel Question 2101
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2. Differential response by baseline seizure count:
S: N=69T: N=71
S: N=12T: N=8
Panel Question 2102
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2. Differential response by baseline seizure count:
S: N=69T: N=71
S: N=12T: N=8
S: N=6T: N=6
Panel Question 2103
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2. Differential response by baseline seizure count:
S: N=69T: N=71
S:N=12T: N=8
S:N=6T: N=6
S: N=7
T: N=12
Panel Question 2104
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Overall Response Varies by Baseline Seizure Count
N=19
N=12
N=20
N=140
Panel Question 2Model-based estimateEmpirical estimate
3. Influential subjects:• GEE
» Observation out of range of others» Subject with a different response pattern than
others• Response patterns in baseline seizures
subgroup graphs» Return to baseline in Sham in >84 subgroup» Possibility that these subjects may be influential
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107Panel Question 2
2 Sham Subjects Respond Differently
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How influential are these 2 subjects?Overall
Panel Question 2
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How influential are these 2 subjects?By Baseline Seizure Frequency
Panel Question 2
Summary Results
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N=191
N=172
N=189
Model-based estimateEmpirical estimate
Statistical ConclusionsStatistical Uncertainty:• Pre-specified primary analysis model
» Not statistically significant by empirical estimate» Not a good fit to data
• Post hoc analysis model» Appropriate but not only possible model» Selected after being un-blinded
111Panel Question 2
Statistical Conclusions (2)Statistical Uncertainty:• Overall treatment effect
» Consistent but statistical significance dependent upon particular GEE assumptions
» Magnitude may be driven by subjects with very high baseline seizure frequency (>84)
» Magnitude sensitive to 2 influential Sham subjects
112Panel Question 2
• Secondary and additional effectiveness outcomes» Median seizure count» Responder rate» Median percent change
• Long-term data» Open-label» No concurrent control arm» Confounded with changes to AEDs» Potential for drop-out due to non-response
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Statistical Conclusions
Panel Question 3113
Post-Approval Study (PAS) Considerations
Federico Soldani, M.D., S.M., Ph.D. Division of Epidemiology
Office of Surveillance and Biometrics114
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
Reminder• The discussion of a PAS prior to FDA determination of
device approvability should not be interpreted to mean FDA is suggesting that the device is safe and effective.
• The plan to conduct a PAS does not decrease the threshold of evidence required by FDA for device approval.
• The premarket data submitted to the Agency and discussed today must stand on their own in demonstrating a reasonable assurance of safety and effectiveness and an appropriate benefit/risk balance.
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General Principles for Post-Approval Studies
• Objective is to evaluate device performance and potential device-related problems in a broader population over an extended period of time after premarket establishment of reasonable evidence of device safety and effectiveness
• Post-approval studies should not be used to evaluate unresolved issues from the premarket phase that are important to the initial establishment of device safety and effectiveness
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Need for Post-Approval Studies • Gather postmarket information
» Long-term performance including effects of re-treatments & device changes
» Real-world device performance (patients and clinicians)
» Effectiveness of training programs» Sub-group performance» Outcomes of concern (safety and
effectiveness)• Account for panel recommendations
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Post-Approval Study Components
• Fundamental study question or hypothesis• Safety endpoints and methods of assessment• Acute and chronic effectiveness endpoints
and methods of assessment• Duration of follow-up
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Important Postmarket Issues• The need to collect safety and effectiveness
data on recipients of the RNS System who are being treated by physicians newly trained on implantation and management of the RNS System
• The need to gather additional patient years of data to contribute to the estimate of the rate of sudden unexplained death in epilepsy (SUDEP)
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PAS1: Long Term Treatment (LTT) Study Study Objectives
To assess the ongoing safety and continue to evaluate the long-term effectiveness of the RNS System for its proposed intended use as an adjunctive therapy in reducing the frequency of seizures in individuals 18 years of age or older with partial onset seizures from no more than two foci that are refractory to two or more antiepileptic medications
Study Design Prospective, Non-Randomized, Multi-Center, 7-year follow-up
Sample Size 230 patients who completed the Feasibility and Pivotal Trials
Primary Endpoint
Total serious adverse event rate (device related and not device related)
Secondary Endpoints
Average percentage change in mean frequency of total disabling seizures relative to the Pre-Implant Period 120
PAS2: Proposed New Enrollment Study Title New Enrollment Study with 1-year follow-up
Study Objectives
Collect one year of safety data on recipients of the RNS System who are being treated by physicians newly trained on implantation and management of the RNS System Gather additional patient years of data to contribute to the estimate of the rate of sudden unexplained death in epilepsy (SUDEP)
Study Design Prospective, Non-Randomized, Multi-Center, 1-year follow-up
Study Hypothesis
For the primary endpoint: the total serious adverse event rate (device related and not device related) at 1 year is not worse than the total SAE rate observed in the first year of the RNS System Pivotal trial, which was 39% (74/191)
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PAS2: Proposed New Enrollment StudySample Size 200 patients will be enrolled at 20 centers
Study Population
Patients 18 to 70 years of age with:• Disabling seizures (simple partial motor, complex partial and/or generalized tonic clonic seizures)• Failed treatment with a minimum of two antiepileptic medications (used in appropriate doses) with adequate monitoring of compliance and the effects of treatment, as determined by the physician investigator• Diagnostic testing as part of standard care that has identifiedno more than two epileptogenic regions
Primary Endpoint
Total serious adverse event rate (device related and not device related) at 1 year for patients treated by physicians newly trained in implantation and use of the RNS System
Secondary Endpoints
SUDEP rate
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Assessment of Proposed Postmarket Plan and Issues for Panel Discussion /1
FDA has concerns about the New Enrollment Study as presented by the company and is seeking the panel’s input on the following points:
1. The sponsor has not proposed a newly enrolled comparison group (e.g., best medical therapy). A comparison group may indeed be critical to evaluate safety and effectiveness. (Panel Question 5a)
2. Apart from SUDEP rate, no other specific safety endpoint is proposed. Other safety endpoints in addition to SUDEP (e.g., intracranial hemorrhage and injuries) could be worth measuring in the new enrollment PAS (Panel Question 5b)
3. 1-year follow up is proposed. A longer duration of follow up (perhaps up to 10 years) may be necessary to estimate the long term safety and effectiveness of this permanently implanted device (Panel Question 5c)
4. Effectiveness data are not planned to be collected during the new enrollment study. Given that the device is a permanent implant, it would be important to monitor effectiveness in the postmarket setting (Panel Question 5d)
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FDA Summation
Lawrence Rodichok, M.D.CDRH/ODE/DNPMD
NeuroPace RNS® System for Epilepsy (P100026)Neurological Devices Panel
February 22, 2013
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FDA Summation – Safety• Procedure associated with significant risks
» No worse than implantation of intracranial or DBS electrodes
» In excess of risks with continued medical therapy• Overall risk
» Comparable to risks with poorly controlled epilepsy» Possible increased risk of intracranial hemorrhage
and injury» Data for full population complete to one year
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FDA Summation – Effectiveness• Significant uncertainty for the primary
endpoint analysis• Pre-specified secondary endpoints
» Not statistically significant» Do not indicate a clinically meaningful benefit
• Largest change in seizure frequency occurred prior to stimulation
• Open label uncontrolled data for effectiveness difficult to interpret
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Benefit to Risk Comparison
• Risks of procedure• Risks of chronic implant in epilepsy
population• Benefit uncertain• Alternatives are available
» Pharmacologic – benefit known, lower risk» VNS – benefit known, lower risk» Mesial temporal resection – benefit > risk
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Thank You!
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