First Clinical Study to Evaluate Safety, Tolerability & PK of DX243 in Healthy Volunteers and Patients With Hearing Loss (DX243-101)

Double-blind, Randomised, Placebo-controlled Phase 1/2a Study of Safety, Tolerability and PK of Single and Repeated SC Doses of DX243 in Healthy Volunteers, and 1-month Safety and Efficacy in Moderately Severe Age-related Hearing Loss

Phase 2a: Multiple Ascending Dose (MAD) in male and female patients with hearing loss:

The study will be conducted according to a randomised, placebo-controlled, double-blind design. A total of 24 patients, otherwise healthy, aged up to 75 years old, with mild to moderate hearing loss will be included. Two cohorts of 12 male or female patients (no ratio is required) will receive two different flat doses (low dose and high dose) ofDX243 or placebo for 29 days using SC administration. In each cohort of 12 patients, 4 will be randomised to placebo and 8 to DX243, so at the end of Phase 2a, 8 patients will have received placebo, 8 the low dose and 8 the high dose of DX243.

The primary objective is to evaluate the safety and tolerability of DX243 administered subcutaneously after repeated doses. The secondary objectives are to detect preliminary signal of efficacy, using speech in noise tests, tonal and vocal audiometry, as well as tinnitus and quality of life.

Study Overview

• Status: Recruiting
• Conditions: Age-related Hearing Loss
• Intervention / Treatment: Drug: DX243; Drug: Placebo

Detailed Description

This is a first-in-human, randomised, double-blind, placebo-controlled Phase 1/2a study designed to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of DX243, a novel investigational compound, in healthy volunteers and patients with mild to moderate age-related hearing loss (ARHL). The study consists of two parts: a Phase 1 segment including single and multiple ascending dose evaluations in healthy volunteers, followed by a Phase 2a extension in patients with hearing impairment. The overall design allows for dose selection and regimen optimisation based on safety and PK results obtained in earlier cohorts.

In the Phase 2a part, 24 otherwise healthy male and female patients aged up to 75 years with up to moderately severe hearing loss will be enrolled. Patients will be randomised in a double-blind manner to receive either DX243 (two dose levels) or placebo. Treatment will consist of once-weekly subcutaneous administrations over 29 days (five injections), with 2 dosing levels selected based on Phase 1 safety, PK and modelling data to achieve target plasma concentrations while minimising local tolerability issues.

The primary objective of the Phase 2a portion is to assess the safety and tolerability of repeated subcutaneous administration of DX243, including treatment-emergent adverse events, local injection site reactions, laboratory parameters, and ECG findings. Secondary and exploratory objectives include characterisation of PK parameters and evaluation of preliminary efficacy signals using a comprehensive battery of audiological tests (including speech-in-noise performance, pure tone audiometry, and auditory brainstem response), tinnitus assessments, and quality-of-life measures. Patients will be followed for up to approximately 6 months after treatment to assess longer-term safety and durability of response.

• Study Type: Interventional
• Enrollment (Estimated): 24
• Phase: Phase 2

Contacts and Locations

Study Locations

• Belgium
  • Liège
    • Liège, Liège, Belgium, 4000
      • Recruiting
      • Centre hospitalier Universitaire de Liège Sart Tilman
      • Contact: Guillaume Gersdorff, MD; Phone Number: +32 043232323; Email: Guillaume.Gersdorff@chuliege.be

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patient having self-reported recent difficulty hearing in noisy environments for at least 6 months prior to screening.
• Patient exhibiting a speech-in-noise hearing deficit in at least one ear;
• Patient having audiometrically-defined normal hearing or up to moderately severe hearing impairment

Exclusion Criteria:

• Current tympanic membrane perforation;
• Current acute or chronic otitis;
• Genetic hearing loss;
• Symmetric or asymmetric severe hearing loss;
• Any therapy known as ototoxic;
• Acute chronic otitis media or otitis externa terminated less than 7 days prior to randomisation;
• History of chronic inflammatory or suppurative ear disease or cholesteatoma;
• History of otosclerosis, suspected perilymph fistula or membrane rupture, suspected retro-cochlear lesion, barotrauma;
• Prior ear surgery of any kind;
• Fluctuating hearing loss;
• Patient with conductive hearing loss;
• History of Meniere's disease, autoimmune hearing loss, radiation-induced hearing loss, acoustic neuroma

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: DX243 low flat dose; Flat dose administered sub-cutaneously for 1 month	Drug: DX243; DX243 10 mg/mL
Experimental: DX243 high flat dose; Flat dose administered sub-cutaneously for 1 month	Drug: DX243; DX243 10 mg/mL
Placebo Comparator: Placebo; Placebo administered sub-cutaneously for 1 month	Drug: Placebo; Placebo solution, matching the external appearance of DX243.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety and tolerability: incidence, nature, severity and causality of treatment emergent adverse events (TEAE) and (Serious) Adverse events (S)(AEs)		Through study completion, an average 7 months
Tolerability at the injection sites using a 1-5 scale Common Terminology Criteria for Adverse Events (CTCAE) for pain, erythema, swelling, induration, nodule and ulceration with 1 : normal and 5: worst possible symptom/sign		For 14 days or up to normalisation after each administration whichever comes first
Number of participants with at least one clinically significant abnormal laboratory result	Prespecified hematology, coagulation, and clinical chemistry laboratory tests will be measured in standard local laboratory units throughout the study. Each analyte will be assessed individually against the applicable reference range and for clinical significance. For this outcome measure, a patient will be counted once if he/she has at least one post-baseline abnormal clinically relevant laboratory value.	For 7 months
Number of Participants With Abnormal ECG Findings	Twelve-lead triplicate ECGs will be obtained at each scheduled assessment throughout the study. PR interval, QRS duration, QT interval, and QTcF interval will be measured on each of the three ECG tracings. Overall ECG interpretation (normal/abnormal) and clinical significance of any abnormality will be determined by the investigator or qualified reader based on review of the triplicate ECG assessment. For this outcome measure, a participant will be counted once if at least one post-baseline ECG assessment is abnormal.	For 7 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Pure Tone Audiometry		For 7 months
Change in speech audiometry		For 7 months
Hearing Handicap Inventory for the Elderly- Screening (HHIE-S) questionnaire score	0 to 8 = 13% probability of hearing impairment (no handicap/no referal) 10 to 24= 50% probability of hearing impairment (mild-moderate handicap/refer) 26 to 40=84% probability of hearing impairment (severe handicap/refer)	For 7 months
Severity of tinnitus	Tinnitus assessment (acouphenometry) and Tinnitus Functional Index (TFI)	For 7 months
Distorsion Product OtoAcoustic Emission (DPOAE)		For 7 months
Quality of Life (QoL) assessed using 15iSSQ scale	The 15-item Speech, Spatial, and Qualities of Hearing Scale is a 15-item questionnaire that evaluates hearing-related quality of life. It measures self-reported abilities in three specific hearing domains: Speech, Spatial, and Qualities of hearing. Higher scores indicate better hearing performance and fewer limitations in daily life.	For 7 months

Collaborators and Investigators

• Sponsor: Dendrogenix

Study record dates

Study Major Dates

• Study Start (Actual): May 13, 2026
• Primary Completion (Estimated): October 1, 2027
• Study Completion (Estimated): October 1, 2027

Study Registration Dates

• First Submitted: April 30, 2026
• First Submitted That Met QC Criteria: June 4, 2026
• First Posted (Actual): June 10, 2026

Study Record Updates

• Last Update Posted (Actual): June 10, 2026
• Last Update Submitted That Met QC Criteria: June 4, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Age-related hearing loss; DX243
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Otorhinolaryngologic Diseases; Sensation Disorders; Ear Diseases; Hearing Loss; Hearing Disorders; Hearing Loss, Sensorineural; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Presbycusis
• Other Study ID Numbers: DX243-101; 2023-505778-14-00 (Ctis)

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: No
• Studies a U.S. FDA-regulated device product: No