•Revised to clarify the ideal order of Clinical Global Impression of Overall Change (CGI) and spasticity assessments •Revised the heading from “(2 to 4 Weeks Before Study Day 1)” to “(Up to 4 Weeks Before Study Day 1)” in order to match the schedule of events •Revised approximate volume of blood collection for haematology and chemistry from 5 to 7 mL based on the revised central laboratory requirements.

•Added language for triplegic participants, to allow dose up to 10 U/kg and not to exceed 340 U to be injected during treatment cycles 2 to 5 when only both lower limbs were treated •Changed exclusion criteria 21 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 •Added to the wording that requires a participant to remain on a stable dose of antispastic medications: to the extent possible unless judged by the investigator to be clinically inappropriate for clarification in Prohibited Medications/Treatments •Added at the study Day 1 visit for both de novo and rollover, the site accessed the IVRS/IWRS to enroll the participant in Method of assignment •The wordings were revised in Treatment Regimen and Dosing to “If a participant met the retreatment criteria, including no indication of an unacceptable safety risk, and it was considered to be clinically appropriate by the investigator, the participant should receive at least 6 U/kg in the study upper limb every 12 to 14 weeks, with the total dose not to exceed the maximum specified for each treatment cycle •Clarified title (Maximum Per-muscle, Per-limb, and Total Body Dose), added row for total maximum dose for both lower limbs, and added footnote to indicate that only 1 upper limb is to be injected •Added For purposes of dose calculation, the participants weight would be rounded to the nearest whole kilogram •Revised to “Participants should may be retreated” if they met the retreatment criteria •Added that study Day 1 is treatment 1/ day 1 for participants who received treatment on that day •Added obtaining study medication kit numbers from and entering exit status to the IVRS/IWRS •Passive range of motion was performed as part of the Modified Tardieu Scale (MTS) and therefore did not need to be identified as a separate procedure.

•For de novo participants revised to specify (Modified Ashworth Scale-Bohannon) MAS-B was to be done on the elbow and wrist of the study limb •Revised study week 42 to study week 48 in “Early Discontinuation of Patients” section •Added that participants will be withdrawn from the study if they develop a medically significant hypersensitivity reaction to the study drug such as angioedema or anaphylaxis, or if a participant becomes pregnant during the study •Added the same investigator should perform this measure at each visit, if possible in section 12.1.10 MAS for consistency across evaluation •Deleted description of how to measure R1 and R2 in section 12.1.11 MTS.

•Specified that the Columbia-Suicide Severity Rating Scale (C-SSRS) is 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 as requested by the United States Food and Drug Administration’s (US FDA's) Division of Neurology Products •Added a +14-day window to study week 48 visit •Modified Exclusion Criterion 11a regarding seizure frequency for exclusion •Modified Exclusion Criterion 12 regarding vulnerable respiratory state •Added Exclusion Criterion 27 to exclude participants with significant suicidality from treatment •Added patient-reported benefit of injection •Added a sentence on use of anti-epileptics •Amended retreatment criteria to specify that participants who experience certain adverse events will not receive further study treatments •Revised paragraph regarding retreatment for participant with adverse events of compromised respiratory function, aspiration, difficulty swallowing, or clinically significant excessive salivation •Clarified that passive range of motion can be performed during the MTS •Clarified to remove time frame for blood sample collection •Clarified regarding patient not receiving treatment or retreatment •Clarification on requirements for weight measurements and that weight must be measured in kilograms •Added “temporal, rectal” to body temperature •Revised MAS-B description to say “study specified” instead of “non-study-specified” velocity and provided detail on scoring to clarify that we do instruct the sites on a specific velocity for MAS-B assessment •Clarified “investigator” to “physician investigator."