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

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: Not yet recruiting
• Conditions: Flexible Hammertoe; Semi-flexible Hammertoe
• Intervention / Treatment: Biological: KN3835

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: Interventional
• Enrollment (Estimated): 470
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Clinical Operations; Phone Number: 800-462-3636; Email: clinicaltrials@endo.com

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Time Frame
Number of Participants with Adverse Events	Observational Day 1 up to Treatment/Retreatment Period Day 360

Secondary Outcome Measures

Outcome Measure	Time Frame
Change from Baseline In Foot Function Index (FFI) Total Score In Part 1 Observational Period	Baseline and up to Observational Day 360
Change from Baseline In FFI Subscales (Difficulty, Pain and Activity Limitation) Scores In Part 1 Observational Period	Baseline and up to Observational Day 360
Change from Baseline In Pain Intensity Numeric Rating Scale (NRS) Score In Part 1 Observational Period	Baseline and up to Observational Day 360
Percentage of Participants That Meet Retreatment/Treatment Criteria In Part 1 Observational Period	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	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	Up to Observational Day 360
Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 1 Observational Period	Baseline and up to Observational Day 360
Percent Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 1 Observational Period	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	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	Up to Observational Day 360
Change from Baseline In FFI Total Score In Part 2 Treatment/Retreatment Period	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	Baseline and up to Treatment/Retreatment Period Day 360
Change from Baseline In Pain Intensity NRS Score In Part 2 Treatment/Retreatment Period	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	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	Up to Treatment/Retreatment Period Day 360
Change from Baseline In Flexion Contracture As Measured By Goniometer in Part 2 Treatment/Retreatment Period	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	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	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	Up to Treatment/Retreatment Period Day 360

Collaborators and Investigators

• Sponsor: Endo USA Inc., a Keenova Therapeutics Company
• Investigators: Study Director: Medical Director, MD, Endo USA Inc., a Keenova Therapeutics Company

Study record dates

Study Major Dates

• Study Start (Estimated): October 11, 2026
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: September 23, 2026
• First Submitted That Met QC Criteria: September 23, 2026
• First Posted (Actual): September 29, 2026

Study Record Updates

• Last Update Posted (Actual): September 29, 2026
• Last Update Submitted That Met QC Criteria: September 23, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Other Study ID 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