Due to study design limitations, this study has been discontinued and will not proceed with the 2nd cohort as contemplated in the original protocol.

This is a Phase 2 open label study to evaluate the safety, tolerability, PK, and PD of multiple dose levels of SC administered ELX-02 in patients with cystinosis with nonsense mutation in at least one allele.

Six patients will be enrolled in the trial.

The study will comprise of the following periods for each patient:

• A screening period of up to 6 weeks
• A total treatment period of 4 weeks
• A safety follow-up period of 4 weeks after the last treatment

Each patient will receive three escalating doses as follows:

• Treatment period 1: ELX-02 0.5 mg/kg SC daily for 7 days (total dose not to exceed 3.5 mg/kg for this week; the daily dose will be individualized to achieve the target weekly exposure of about 47.5 µg*h/mL)
• Treatment period 2: ELX-02 1.0 mg/kg SC daily for 7 days (total dose not to exceed 7.0 mg/kg for this week; the daily dose will be individualized to achieve the target weekly exposure of about 95 µg*h/mL)
• Treatment period 3: ELX-02 2.0 mg/kg SC daily for 14 days (total dose not to exceed 14 mg/kg for these two weeks; the daily dose will be individualized to achieve the target weekly exposure of about 190 µg*h/mL)

Patients must meet all of the following criteria to participate in this study:

1. Male or female patients who, at the time of screening, are 18 years of age or older (Cohort 1) or ≥12 years of age (Cohort 2)
2. A diagnosis of nephropathic cystinosis and biallelic CTNS mutations, including at least one nonsense mutation
3. Patients should have a mild to moderate disease estimated glomerular filtration rate ≥40 mL/min/1.73m2 using the Chronic Kidney Disease Epidemiology Collaboration CKD-EPI formula
4. Body mass index of 19.0 to 30.0 kg/m2. Patients with a lower BMI may be entered into the study at the discretion of the Investigator following consultation with the Sponsor
5. Renal transplant permitted with stable graft function (serum creatinine) for 3 months prior to Screening

Patients with any of the following characteristics/conditions will not be included in the study:

1. Participation in clinical study including administration of any investigational drug or device in the last 30 days or 5 half-lives (whichever is longer) prior to investigational product dosing in the current study
2. Concomitant use of cysteamine bitartrate from 7 days prior to baseline until 7 days following final administration ELX-02
3. An average systolic blood pressure and/or diastolic blood pressure ≥95th percentile for sex, age, and height on 3 or more occasions during the screening period
4. Patients without documented prior aminoglycoside exposure who have a mitochondrial mutation that has been shown to increase sensitivity to aminoglycosides
5. Known relevant allergy or hypersensitivity to aminoglycosides