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Safety, Tolerability and Efficacy of Intracochlear SENS-601 in Children with GJB2‑Related Hearing Loss

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on children who have a rare form of hearing loss caused by changes in the GJB2 gene, which can make it difficult for them to hear everyday sounds. The investigational medicine being tested is a liquid called SENS-601 that is placed directly into the inner ear, or cochlea, using a small device known as the SPHYNX administration system; this method is called an intracochlear injection because the medicine is delivered inside the hearing organ.

The purpose of the trial is to determine whether the treatment is safe and whether it can improve hearing. Participants will first receive a single injection in one ear, followed later by injections in both ears. Over the following months they will undergo simple hearing checks, including an auditory brainstem response test, which records how the brain reacts to sounds, and a pure-tone audiometry test, which measures the faintest sounds a person can hear, along with questionnaires about hearing ability. The study will monitor any side effects and collect information on how well the treatment works.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessments

    You will attend an initial visit after joining the study. during this visit, a series of hearing tests will be performed, including auditory brainstem response and pure‑tone audiometry. you will also complete questionnaires about your hearing experience and provide blood samples that will be used to measure immune and inflammatory markers.

  2. Step 2

    First intracochlear injection (unilateral)

    A single dose of sens-601 will be injected into one ear using the sphynx administration system. the injection is given directly into the cochlea (the inner part of the ear). the exact amount of the dose is defined by the study protocol and is administered as a one‑time injection for each ear.

  3. Step 3

    Immediate post‑procedure monitoring

    Right after the injection, you will be observed for a short period. staff will check vital signs, look for any immediate side effects, and repeat basic hearing measurements to ensure the procedure was safe.

  4. Step 4

    Safety follow‑up visits (part 1)

    Over the next weeks, you will return for scheduled visits. at each visit, the study team will ask about any new symptoms, record any adverse events, and perform additional hearing tests. these visits are designed to assess the safety and tolerability of the injection and the device used for delivery.

  5. Step 5

    Second intracochlear injection (bilateral)

    After the safety period is completed, a second injection will be performed, this time in the opposite ear, so that both ears receive sens-601. the same sphynx administration system will be used, and the procedure follows the same steps as the first injection.

  6. Step 6

    Post‑procedure monitoring (part 2)

    Following the bilateral injection, you will again be monitored for a short period to check for immediate reactions and to repeat basic hearing measurements.

  7. Step 7

    Long‑term follow‑up assessments

    Throughout the remainder of the study, you will attend regular visits. each visit will include detailed hearing evaluations such as auditory brainstem response and pure‑tone audiometry, repeated questionnaires, and blood tests to measure immune response and other biomarkers. the purpose of these visits is to evaluate the effectiveness of the treatment and to continue monitoring safety.

  8. Step 8

    Final study visit

    At the conclusion of the study, a final assessment will be performed. all data collected during the trial, including hearing test results, questionnaire responses, and laboratory findings, will be reviewed to determine the overall outcome of the treatment.

Who can join the trial?

7 criteria

  • Be a boy or girl who is at least 6 months old and not older than 6 years (if born early, use the age they would be if born at full term) at the time of the treatment.
  • Have a diagnosis of congenital bilateral severe sensorineural hearing loss – meaning the hearing loss is present from birth, affects both ears, and is caused by damage to the inner ear or hearing nerve.
  • Have a parent or legal guardian (called a legally authorized representative) sign a written consent form and be able to follow all study requirements.
  • Carry specific disease‑causing changes in both copies of the GJB2 gene (called biallelic pathogenic or likely pathogenic variations), confirmed by a laboratory test called DNA sequencing.
  • Show a normal inner ear structure, specifically a normal cochlea (the spiral part of the inner ear that helps hear) and normal internal auditory canals (small pathways that carry sound nerves).
  • Be part of or receive care from a health care system (for example, have health insurance or be treated at a hospital).
  • Have the study doctor confirm that all criteria are met after a review by a team of specialists (multidisciplinary evaluation).

Who cannot join the trial?

15 criteria

  • Have a history of chronic (long‑lasting) acute (sudden) or major disease.
  • Have documented other causes of congenital bilateral hearing loss linked to mutations in genes other than GJB2. (Congenital means present at birth; bilateral means both ears.)
  • Require vaccination with a live attenuated vaccine from screening up to 3 months after receiving SENS‑601. (A live attenuated vaccine uses a weakened form of a germ.)
  • Are participating in any other interventional clinical study. (A study that tests a new treatment.)
  • Have any other condition that the Investigator believes could affect safety, ability to follow the study, or the study results.
  • Are expected to be non‑compliant with the study protocol, according to the Investigator. (Non‑compliant means not following the study rules.)
  • Have a history of allergic or severe reactions to any ingredient (excipients) in SENS‑601, the SPHYNX system, or other medicines used in the study.
  • Plan to use or have used other investigational drugs within 5 half‑lives of SENS‑601, or have been in a study with an investigational drug in the past 12 weeks, whichever is longer. (Investigational drugs are not yet approved; half‑life is the time it takes for half of a drug to leave the body.)
  • Have previously received a gene therapy in a clinical study. (Gene therapy involves delivering new genetic material into cells.)
  • Have hearing loss caused by developmental disorders such as cochlear aplasia or hypoplasia or other diseases or risk factors. (These terms mean the inner ear is missing or under‑developed.)
  • Have a prior or current cochlear implant in the ear that will receive SENS‑601. (A cochlear implant is a device placed in the ear to help hearing.)
  • Have hearing loss due to any other cause that would reduce the function of hair cells in the ear. (Hair cells are tiny cells that help turn sound into signals for the brain.)
  • Have other causes of hearing loss such as loss in only one ear (unilateral), chronic conductive hearing loss, malformation syndrome, or syndromic hearing loss. (Conductive loss means sound is blocked before reaching the inner ear; syndromic means hearing loss is part of a broader genetic condition.)
  • Have a contraindication (a reason it is unsafe) to corticosteroid therapy and/or immunosuppressive or immunomodulatory therapy. (These medicines affect the immune system.)
  • Have a contraindication to the planned surgery, to anesthesia, or a history of long‑term use of medicines that can damage the ear (ototoxic). (Ototoxic medicines can harm hearing.)
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Investigated drugs

SENS-601 is an investigational medicine that is being tested to help children who have hearing loss caused by specific genetic changes. In the study, the medicine is a clear liquid that is injected directly into the inner ear (the cochlea) through a very small needle. The goal is to see if putting the medicine into the cochlea is safe and if it can improve the child’s ability to hear.

The SPHYNX administration system is a special device used in the trial to deliver SENS-601 into the cochlea. It is designed to place the medicine precisely and gently, minimizing any damage to the delicate structures of the inner ear. The study will evaluate how well the system works, how safe it is for patients, and whether it helps the medication provide a clinical benefit.

What is already known about the treatment

SENS-601 - It is a sterile solution that is injected directly into the inner ear (intracochlear injection) using the SPHYNX delivery system. SENS-601 is an experimental gene‑replacement therapy currently in Phase 1/2 clinical trials and is not yet approved for general medical use. It is being studied to treat hearing loss caused by biallelic pathogenic variants of the GJB2 gene. The treatment works by delivering a functional copy of the GJB2 gene to cochlear cells so they can produce the missing connexin‑26 protein, which is essential for normal hearing, and it is classified as a gene‑therapy administered by intracochlear injection.

Investigated diseases

GJB2-related hearing loss - This hereditary condition is caused by two faulty copies of the GJB2 gene, which affect the protein connexin 26 in the inner ear. The loss of connexin 26 disrupts the movement of ions that are needed for sound signaling, leading to sensorineural hearing loss. It usually appears at birth or in early childhood and can become gradually worse over time. The disorder is limited to hearing and does not involve other body systems.
Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase I/IITrial ID2026-525698-38-00Protocol codeSENS-601-101Estimated enrolment18 patientsSponsorSensorion

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