•Revised the pronator teres dose from 2 U/kg to 1.5 U/kg and the number of sites from 2 to 1 •Revised approximate volume of blood collection for hematology and chemistry laboratory assessments from 5 millilitres (mL) to 7 mL (participants weighing < 15 kg) and from 12 to 14 mL (participants weighing ≥ 15 kg) to meet revised central laboratory requirements.

•Added language for diplegic participants, allowing injection of a dose up to 10 U/kg and not to exceed 340 U during Treatment Cycles 2 to 5 when both lower limbs were treated •Changed designation of visit for Exclusion Criterion 23 regarding history of fracture in the study upper limb within 12 months from “prior to the screening visit” to “prior to the Day 1 visit,” for consistency with other criteria •For Treatment Cycle 1 for de novo participants, clarified that 8 U/kg was to be injected either in the single study lower limb or divided between both study lower limbs only for diplegic participants; for Treatment Cycles 2 through 5 for all participants, clarified the description of dose limitations • Clarified that participants who met the retreatment criteria “may be reinjected” rather than “should be reinjected” •Clarified language regarding retreatment visits, including determination of whether the dose was clinically appropriate or dose reduction relative to the last injection received was required •Added for Modified Tardieu Scale (MTS) that it should be done with knee extended • For de novo participants, revised to specify Modified Ashworth Scale – Bohannon (MAS-B) was to be done in the ankle of the study limb(s) only (deleted the knee) •Added MAS-B for knee flexors and any other muscles in the treatment plan •Deleted Edinburgh Visual Gait (EVG) score at subsequent Treatment/Retreatment Visit •At Early Discontinuation, corrected “Study Week 42” to “Study Week 48” •Revised language to allow therapists to perform MAS-B.

•Specified that Columbia-Suicide Severity Rating Scale (C-SSRS) was to be performed as a safety measure for participants ≥ 6 years of age at Day 1, and provided description of scale, data handling, and reference information. Request from US Food and Drug Administration (FDA) •Added a +14-day window to Study Week 48 visit •Modified Exclusion Criterion 13a regarding seizure frequency for exclusion •Modified Exclusion Criterion 14 regarding vulnerable respiratory state •Added Exclusion Criterion 29 to exclude participants with significant suicidality from treatment •Added collection of patient-reported benefit of injection •Clarified that anti-epileptics were permissible during the study •Amended retreatment criteria to specify that participants who experienced certain adverse events, including compromised respiratory function, aspiration, difficulty swallowing, or clinically significant excessive salivation, would not receive further study treatments •Removed requirement of true equinus foot deformity •Updated serious adverse event (SAE) language •Clarified that physician investigator, not investigator, was to conduct Clinical Global Impression of Overall Change (CGI) by Physician.