A Study of TYRA-300 in Children With Achondroplasia: BEACH301

Inclusion Criteria:

• Aged 3 to 10 years old (inclusive) at the time of consent.

• Informed consent provided by parent(s) or legal guardian(s). As study participantsare less than 18 years old, participants are willing and able to provide writtenassent (where applicable and required).

• Molecular diagnosis of achondroplasia (FGFR3 G380R).

• Radiographically confirmed open growth plates at Screening, as determined by boneage X-ray.

• Able to stand and ambulate independently.

• Able to take oral medication.

• Sentinel Safety Cohort only: aged 5 to 10 years old (inclusive).

• Cohort 1 only: aged 3 to 10 years old (inclusive) and are naive to prior growthaccelerating therapy.

• Cohort 2 only: aged 3 to 10 years old (inclusive) and have received prior growthaccelerating therapy.

Exclusion Criteria:

• Presence or history of any concurrent disease or condition that would interfere withstudy participation, safety evaluations, or any uncontrolled or untreated conditionthat could impact pediatric growth.

• Diagnosis of endocrine condition that alters calcium/phosphate homeostasis.

• Prior limb lengthening surgery or planned or expected to have limb lengtheningsurgery while enrolled in the study.

• Taking medications that are strong inhibitors or inducers of cytochrome P450 (Cyp) 3A4.

• History or current evidence of corneal or retinal disorder/keratopathy.

• Presence of guided growth hardware/8 plates. Planned or anticipated orthopedicsurgeries.