Study to Assess the Long-term Safety of KN3835 in the Treatment and Retreatment of Flexible/Semi-Flexible Hammertoe (HMT)

September 23, 2026 updated by: Endo USA Inc., a Keenova Therapeutics Company

A Phase 3, Multi-center Extension Study to Evaluate the Long-term Safety, Efficacy, and Maintenance of Response of KN3835 in the Treatment and Retreatment of Flexible/Semi-flexible Hammertoe

The primary purpose of this study is to assess the long-term safety of treatment and retreatment with KN3835 for flexible/semi-flexible HMT.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This extension study is for eligible participants who completed parent study KN3835-313 HMT. The study comprises 2 parts:

  • Part I: a double-blind Observation Period from Observational Day 1 to Observational Day 360, and
  • Part 2: an optional open-label Treatment/Retreatment Period from Observational Day 180 (Treatment/Retreatment Day 1) to Treatment/Retreatment Day 360 (End of Study).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
470

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 75 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Were enrolled in and completed Study KN3835-313 (participants who completed the study are those that completed the Day 57/End of Study Visit, were assessed for safety, and received at least 1 dose of study intervention).
  • Has no significant medical history or examination findings related to the foot to be treated, which in the investigator's opinion, would make the participant unsuitable for study intervention administration or study required evaluations.
  • If female, be of non-childbearing potential or, if of childbearing potential, be non-pregnant, non-lactating and agree to use effective contraception when with a male partner for the duration of the study and for 28 days after treatment.
  • Be willing and able to comply with all protocol required visits and assessments.

Key Exclusion Criteria:

  • Has any significant medical condition, or a serious or severe event in the parent study or any ongoing event from the parent study, which in the investigator's opinion, would make the participant unsuitable for enrollment in the study.
  • Has received or plans to receive surgical or nonsurgical treatments on the foot or toe that was treated for the duration of study participation.

Note: Other inclusion/exclusion criteria may apply.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Observation then KN3835

After observation during Part 1 of the study, participants will have the option to receive treatment or retreatment with KN3835 in Part 2.
Biological: KN3835

Participants will receive KN3835 in Part 2 of the Study

Other Names:
  • EN3835
No Intervention: Observation Only

Participants will be observed through Part 1. After completion of Part 1, participants will have the option to be observed only during Part 2 of the study.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Number of Participants with Adverse Events
Time Frame: Observational Day 1 up to Treatment/Retreatment Period Day 360
Observational Day 1 up to Treatment/Retreatment Period Day 360

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Change from Baseline In Foot Function Index (FFI) Total Score In Part 1 Observational Period
Time Frame: Baseline and up to Observational Day 360
Baseline and up to Observational Day 360
Change from Baseline In FFI Subscales (Difficulty, Pain and Activity Limitation) Scores In Part 1 Observational Period
Time Frame: Baseline and up to Observational Day 360
Baseline and up to Observational Day 360
Change from Baseline In Pain Intensity Numeric Rating Scale (NRS) Score In Part 1 Observational Period
Time Frame: Baseline and up to Observational Day 360
Baseline and up to Observational Day 360
Percentage of Participants That Meet Retreatment/Treatment Criteria In Part 1 Observational Period
Time Frame: Observational Day 180
Observational Day 180
Percentage of Participants Reporting To Be "Quite Satisfied" and "Very Satisfied" On The Subject Satisfaction With Treatment Scale In Part 1 Observational Period
Time Frame: Up to Observational Day 360
Up to Observational Day 360
Percentage Participants with Investigator Reported "Minimal Improvement", "Much Improvement", or "Very Much Improvement" on the Clinician Global Impression of Change Scale (CGIC) Scale Score in Part 1 Observational Period
Time Frame: Up to Observational Day 360
Up to Observational Day 360
Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 1 Observational Period
Time Frame: Baseline and up to Observational Day 360
Baseline and up to Observational Day 360
Percent Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 1 Observational Period
Time Frame: Baseline and up to Observational Day 360
Baseline and up to Observational Day 360
Change from Baseline In The Patient Global Impression of Severity (PGIS) HMT Overall Scale Score in Part 1 Observational Period
Time Frame: Baseline and up to Observational Day 360
Baseline and up to Observational Day 360
Percentage Of Participants reporting "Minimal Improvement", "Much Improvement", or "Very Much Improvement" on the Patient Global Impression of Change Scale (PGIC) HMT Overall Scale Score in Part 1 Observational Period
Time Frame: Up to Observational Day 360
Up to Observational Day 360
Change from Baseline In FFI Total Score In Part 2 Treatment/Retreatment Period
Time Frame: Baseline and up to Treatment/Retreatment Period Day 360
Baseline and up to Treatment/Retreatment Period Day 360
Change from Baseline In FFI Subscales (Difficulty, Pain and Activity Limitation) Scores In Part 2 Treatment/Retreatment Period
Time Frame: Baseline and up to Treatment/Retreatment Period Day 360
Baseline and up to Treatment/Retreatment Period Day 360
Change from Baseline In Pain Intensity NRS Score In Part 2 Treatment/Retreatment Period
Time Frame: Baseline and up to Treatment/Retreatment Period Day 360
Baseline and up to Treatment/Retreatment Period Day 360
Percentage of Participants Reporting To Be "Satisfied" and "Very Satisfied" On The Subject Satisfaction With Treatment Scale In Part 2 Treatment/Retreatment Period
Time Frame: Up to Treatment/Retreatment Period Day 360
Up to Treatment/Retreatment Period Day 360
Percentage Of Participants with Investigator Reported "Minimal Improvement", "Much Improvement", or "Very Much Improvement" on the CGIC HMT Overall Scale Score in Part 2 Treatment/Retreatment Period
Time Frame: Up to Treatment/Retreatment Period Day 360
Up to Treatment/Retreatment Period Day 360
Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 2 Treatment/Retreatment Period
Time Frame: Baseline and up to Treatment/Retreatment Period Day 360
Baseline and up to Treatment/Retreatment Period Day 360
Percent Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 2 Treatment/Retreatment Period
Time Frame: Baseline and up to Treatment/Retreatment Period Day 360
Baseline and up to Treatment/Retreatment Period Day 360
Change from Baseline In The PGIS HMT Overall Scale Score in Part 2 Treatment/Retreatment Period
Time Frame: Baseline and up to Treatment/Retreatment Period Day 360
Baseline and up to Treatment/Retreatment Period Day 360
Percentage Of Participants reporting "Minimal Improvement", "Much Improvement", or "Very Much Improvement" on the PGIC HMT Overall Scale Score in Part 2 Treatment/Retreatment Period
Time Frame: Up to Treatment/Retreatment Period Day 360
Up to Treatment/Retreatment Period Day 360

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Endo USA Inc., a Keenova Therapeutics Company

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Medical Director, MD, Endo USA Inc., a Keenova Therapeutics Company

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 11, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 23, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 23, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 29, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 29, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • KN3835-314 HMT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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