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| General |
| Study Status |
Completed |
Application Number /
Requirement Number |
P190027 / PAS001 |
| Date Original Protocol Accepted |
04/10/2020
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| Date Current Protocol Accepted |
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| Study Name |
TOBA II BTK Continued Follow-up Study
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| Device Name |
Tack Endovascular System (4F, 1.5-4.5mm)
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| Clinical Trial Number(s) |
NCT02942966
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| General Study Protocol Parameters |
| Study Design |
Prospective Cohort Study
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| Data Source |
New Data Collection
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| Comparison Group |
Objective Performance Criterion
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| Analysis Type |
Descriptive
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| Study Population |
Transit.Adolescent B(as adults): 18 yrs < 22 yrs,
Adult: At least 22 yrs
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| Detailed Study Protocol Parameters |
| Study Objectives |
TOBA II BTK Continued Follow-Up Study. This study should be conducted per protocol CA 0137, Rev C (dated September 14, 2017). This study is a prospective, multi-center follow up of the TOBA II BTK pivotal study (G160144) that treated 233 subjects from 41 investigational sites. It will evaluate the long-term safety and effectiveness of the Tack Endovascular System® (4F, 1.5-4.5mm). All 205 remaining subjects, active at the end of the 6-month evaluation, will continue to be followed annually through 36 months.
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| Study Population |
Continued follow-up of the IDE cohort
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| Sample Size |
205 remaining IDE subjects, active at the end of the 6-month evaluation
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| Key Study Endpoints |
Follow-up at the 1, 2- and 3-year timepoints will include the following:
Rutherford Classification
Wound, Ischemia, and foot Infection (WIfI) grade
wound assessment
target limb resting ABI
EQ-5D-3L
Walking Impairment Questionnaire (WIQ)
major adverse event (MAE) occurrence
adverse event occurrence
review of concomitant medications (antiplatelets/anticoagulants).
Follow-up at the 1-year timepoint will also include duplex ultrasound (DUS) and X-ray assessment of implanted Tacks.
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| Follow-up Visits and Length of Follow-up |
3 years post-procedure
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| Interim or Final Data Summary |
| Interim Results |
Freedom from amputation of the target limb (above the knee), clinically driven TVR, clinically driven TLR and survival at 24 months (750 days) was 94.4%, 73.1%, 73.6% and 78.0% respectively.
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| Actual Number of Patients Enrolled |
A total of 233 subjects were enrolled in the study; 205 subjects were available at 6 months for the continued follow-up study
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| Actual Number of Sites Enrolled |
41 sites across the US and outside the US
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| Patient Follow-up Rate |
83.6% (143/171) at 24months and 91.6% (120/131) at 36 months
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| Final Safety Findings |
Primary Safety and Effectiveness
The TOBA II BTK study met both its primary safety and effectiveness endpoints. The primary safety endpoint of major adverse limb events (MALE) plus perioperative death (POD) at 30
days) was 1.3% [95% confidence interval (CI): 0.3%, 3.8%] in the ITT group and 0.9% [95% CI: 0.1%, 3.4%] in the PP group, compared to the 12% performance goal (PG).
The primary effectiveness endpoint of freedom from major adverse limb events (MALE) at 6 months +
perioperative death (POD) at 30 days) was 95.7% (95% CI: 91.9%,97.8%) in the intent to treat (ITT)
group and 95.9% [95% CI:92.0%,98.0%] in the per protocol population compared to 74% PG.
Secondary Endpoints
Tacked Segment Patency and Assisted Tacked Segment Patency at 12 months in ITT patients was 76.9% [95% CI :71.8%, 81.9%] each.
Secondary Tacked Segment Patency and Target Segment PSVR patency at 12 months in ITT patients was 87.6% [95% CI: 83.4%,91.7%) and 63.7% [95% CI: 57.8%,69.6%] respectively.
Tack embolization, migration or fracture at 12 months in ITT patients was 0.0% (0/146) [95% CI: 0.0%,2.5%] for each event.
The Kaplan Meier (KM) freedom from amputation of the target limb in ITT patients was at 36 months 95% [95% CI: 91.8%, 98.3%].
The KM freedom from survival at 36 months in ITT patients was 66.0% [95% CI: 58.7%, 73.3%]. A total of 64 patients died in the study. Sixty-three (63) of the 64 deaths were adjudicated by the Clinical Events Committee (CEC) to be unrelated to the study procedure and one (1) was adjudicated to be unknown. All 64 deaths were adjudicated by the CEC to be unrelated to the device.
Freedom from clinically driven target vessel revascularization in ITT patients at 36 months was 67.4% with 95% confidence interval (59.6%, 75.1%).
The KM freedom from clinically driven target lesion revascularization in ITT patients at 36 months was 69.6% [ 95% CI: 62.6%, 76.7%].
Freedom from major adverse limb events (MALE) plus perioperative death (POD) in ITT patients at 36 months was 91.6% [95 % CI: 87.6%, 95.6%].
Significant improvement in measured Rutherford class occurred in ITT patients from baseline to 12, 24, and 36 months (p<0.0001).
Significant positive changes in measured ABI and TBI in the target limb occurred in ITT patients from baseline to 12, 24, and 36 months (p<0.0001).
Significant improvement in wound grade occurred in ITT patients from baseline to 12, 24 and 36 months (P<0.0001).
Significant improvement occurred in foot infection grade in ITT patients from baseline to 12 months (0.0119), 24 months (<0.0001 and 36 months (P=0.0002).
Significant positive changes occurred in EQ-VAS score in ITT patients from baseline to 12 months (p=0.0004), 24 months (p=0.0035) and 36 months (p=0.0178) and Walking Impairment Questionnaire (overall) occurred from baseline to 12, 24, and 36 months (p < 0.0001).
No unanticipated device effect occurred in the study.
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| Study Strengths & Weaknesses |
The study met both safety and effectiveness endpoints. However, this was not a randomized trial. The continued follow-study results were not evaluated with formal hypothesis testing.
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| Recommendations for Labeling Changes |
Labeling change is recommended to reflect the long-term results of the continued post approval study. The labeling change should include a new section in the label showing a summary of the post- approval study results (final endpoint results, follow-up rate etc.), strengths and limitations of the PAS.
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