Major changes included: primary and secondary endpoints defined at prespecified timepoints aligned with the duration of the pharmacological effect of LA 45 mg 6 month; other efficacy endpoints added to provide a more comprehensive evaluation of LA 45 mg 6 month at each scheduled assessment; biochemical assessments for hormonal flare/AOC phenomenon added; adverse events of special interest (AESIs) including neuropsychiatric events, seizure/convulsion, injection site reaction, and hypersensitivity reaction added to align with current LupronDepot US package insert; pubertal response to GnRHa stimulation test added at Screening for naïve subjects to align with the LH level for biochemical diagnosis of CPP used in clinical practice; timing of withdrawal criteria for inadequate suppression changed from Week 8 to Week 24 to avoid early withdrawal of subjects who may need more time to reach hormonal suppression in response to long acting formulation; added procedures for rescreening.

Major changes included: alternative study procedures related to subject safety in response to the COVID19 pandemic added throughout. The following alternative procedures were permitted per protocol: ○ If a subject could not come to the site because of an unforeseen circumstance (e.g., the COVID-19 pandemic), study visits could be conducted virtually by site staff (e.g., by phone or video) or by a qualified home healthcare nurse in a non-hospital/clinic environment (e.g., the subject's home) at the request of the investigator and with the agreement of the subject's parent or legal guardian. Patient-reported outcome entries could be administered by site staff over the phone and responses collected on paper (source) and transcribed into EDC or entered by site staff directly into an electronic collection system. AbbVie was to be notified if these changes occurred. Supplemental study case report forms were completed in the event of COVID-19 related missed/virtual visits, study drug interruptions or discontinuations, or AEs (including capture of specific signs/symptoms of infection and testing results). ○ In unforeseen circumstances (e.g., the COVID-19 pandemic), the study drug injection could be administered and GnRHa stimulation test and required gonadotropins and sex steroids blood samples collection could be performed by a home healthcare nurse at the subject's home. If permitted by local regulations, provisioning of study drug and generic LA for stimulation test for direct to-patient and direct-from‑patient transfer because of unforeseen circumstances (e.g., the COVID-19 pandemic) was available upon request. In the event of a home healthcare nurse performing the study drug injection at the subject's home, the injection site reaction assessment was to be conducted by the home healthcare nurse. AbbVie was to be notified if any of these situations occurred.

(con't) ○ If a subject could not visit the site because of unforeseen circumstances (e.g., the COVID-19 pandemic), laboratory and PK samples could be collected by a home healthcare service and sent to the central laboratory. If the central laboratory could not be used to test samples because of unforeseen circumstances (e.g., the COVID-19 pandemic), laboratory samples could be collected and tested at a local laboratory. AbbVie was to be notified if any of these situations occurred.