A Study to Assess the Efficacy, Safety, and Pharmacokinetics of Debio 4326 in Pediatric Participants With Central Precocious Puberty (LIBELULA™ Clinical Trial)

Inclusion Criteria:

1. Diagnosis of central precocious puberty.

2. Onset of development of sex characteristics (i.e., breast development in girls ortesticular enlargement in boys according to the Tanner method) before the age of 8years in girls and 9 years in boys.

3. Initially, only participants aged (a) 5 to 8 years inclusive (i.e., <9 years) areeligible. The Sponsor will determine based on the recommendation of the DMCfollowing the interim analysis whether participants aged (b) 2 to 4 years inclusive (i.e., <5 years) and/or (c) 9 to 10 years inclusive (i.e., <11 years) may berecruited.

4. Participant to receive at least 1 year of gonadotropin-releasing hormone agonist (GnRHa) therapy from study treatment start.

5. (a) Pre-treated participants: Start of initial GnRHa therapy no later than 18 monthsafter onset of the first signs of CPP.

(b) Treatment-naive participants: Start of Debio 4326 treatment no later than 18months after onset of the first signs of CPP.

6. (a) Pre-treated participants: Difference between bone age (Greulich and Pyle method)and chronological age of ≥1 year based on historical values at the initiation of theGnRHa therapy.

(b) Treatment-naive participants: Difference between bone age (Greulich and Pylemethod) and chronological age of ≥1 year.

7. (a) Pre-treated participants: Pubertal-type LH response (LH ≥6 IU/L) following aGnRH/GnRHa stimulation test, or random non-stimulated serum LH >0.5 IU/L (ifconsidered local standard of care), based on historical values prior to theinitiation of GnRHa therapy.

(b) Treatment-naive participants: Pubertal-type LH response (≥6 IU/L) 30 minutesfollowing a GnRHa [leuprolide acetate 20 micrograms per kilogram (μg/kg)subcutaneous injection (SC)] stimulation test before treatment initiation.

8. (a) Pre-treated participants: Clinical evidence of puberty, defined as TannerStaging ≥2 for breast development for girls and testicular volume ≥4 milliliter (mL) (cubic centimeter [cc]) for boys, prior to the initiation of GnRHa therapy.

(b) Treatment-naive participants: Clinical evidence of puberty, defined as TannerStaging ≥2 for breast development for girls and testicular volume ≥4 mL (cc) forboys.

Exclusion Criteria:

1. Gonadotropin-independent (peripheral) precocious puberty: gonadotropin-independentgonadal or adrenal sex steroid secretion.

2. (a) Pre-treated participants: Non-progressing, isolated premature thelarche prior tothe initial GnRHa therapy.

(b) Treatment-naive participants: Non-progressing, isolated premature thelarche.

3. Presence of an unstable intracranial tumor or an intracranial tumor potentiallyrequiring neurosurgery or cerebral irradiation. Participants with hamartomas notrequiring surgery are eligible.

4. Any other condition or chronic illness possibly interfering with growth (e.g., renalfailure, diabetes, moderate to severe scoliosis, previously treated intracranialtumor).

5. Other than GnRHa therapy in pre-treated participants, any ongoing treatment with apotential effect on serum levels of gonadotropins or sex steroids, or possiblyinterfering with growth, opioids, central nervous system [CNS] stimulants).

6. Prior or current therapy with medroxyprogesterone acetate, growth hormone, orInsulin-like growth factor-1 (IGF-1).

7. Diagnosis of short stature, i.e., more than 2.25 standard deviations (SD) below themean height-for-age.

8. Known history of seizures, epilepsy, and/or central nervous system disorders thatmay have been associated with seizures or convulsions.

9. Prior (within 2 months of study treatment start) or current use of medications thathave been associated with seizures or convulsions.

10. Use of anticoagulants (heparin or coumarin derivatives).

Note: Other inclusion/exclusion criteria mentioned in the protocol may apply.