Clinical Research Directory

Inclusion Criteria: 1. Prior to screening, the guardians and children with ACH (if applicable) must voluntarily provide signed informed consent. 2. Patients with a clear clinical diagnosis of ACH confirmed by genetic testing for an FGFR3 mutation. 3. Male or female, age at screening: Dose Escalation Part A: 6 to \< 12 years (inclusive 6 years) Dose Escalation Part B: 3 to \< 6 years (inclusive 3 years) RDE Confirmation Part: 3 to \< 12 years (inclusive 3 years). 4. Have completed at least 6 months (i.e., the "Day 181" visit) of growth assessment and observation of natural history of ACH in the observational study (ABSK061-001) before study entry. 5. Tanner Stage 1 breast development for females or Tanner Stage 1 external genitalia development for males at screening Exclusion Criteria: 1. Known allergy or hypersensitivity to any component of the study drug. 2. Bone age ≥ 14 years as assessed by the investigator based on hand and wrist X-ray. 3. Have a form of skeletal dysplasia other than ACH or known medical conditions that result in short stature or abnormal growth, including but not limited to severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN), Turner syndrome, pseudoachondroplasia, inflammatory bowel disease, chronic renal insufficiency, active celiac disease a, Vitamin D deficiency b, untreated hypothyroidism c, poorly controlled diabetes (HbA1c ≥8.0%) or diabetic complications 4. History or presence of injury or disease of the growth plate(s), other than ACH, that affects growth potential of long bones. 5. AGV ≤ 1.5 cm/year over at least 6 months (i.e., must have completed the 'Day 181' visit) in the observational study (ABSK061-001), or current evidence of growth plate closure (proximal tibia, distal femur). 6. Current epiphyseal injury (Salter-Harris fracture) or severe hip pain. 7. For ACH-related complications: current severe sleep apnea, symptomatic and/or requiring intervention for hydrocephalus, or spinal cord compression at the cranio-cervical junction, or prior ventriculoperitoneal shunt surgery. 8. Have received any dose of medications affecting stature or body proportionality, such as human growth hormone, insulin-like growth factor 1 (IGF-1), or anabolic steroids within 12 months prior to screening. 9. Prior treatment with any CNP analogues or FGFR inhibitors. Prior use of any investigational drugs or investigational medical devices that affect height or body proportion. 10. History of any prior bone-related surgery that affects long bone growth, such as orthopaedic reconstructive surgery, limb lengthening, or osteotomy (patients who have previously undergone foramen magnum decompression or intervertebral disc/laminectomy are allowed if they have fully recovered after surgery and bone healing has occurred for at least 6 months. Patients who have previously undergone eight-plate epiphysiodesis are allowed if the plate has been removed and healed for at least 4 weeks).