Number of subjects with TEAE, TESAE, and TEAE leading to discontinuation during this long-term extension study

Open-label extension (OLE) Safety Population defined as all subjects who took at least one dose of ATB200/AT2221 combination treatment in Study ATB200-07

Motor function was measured using the 6-minute walk distance (meters)

Motor function was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 39 subjects in the Treatment Continued Group and 18 subjects in the Treatment Switched Group.

Pulmonary function was measured by sitting % predicted forced vital capacity (FVC)

Pulmonary function was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 41 subjects in the Treatment Continued Group and 15 subjects in the Treatment Switched Group.

Strength was measured by manual muscle testing (MMT) using the Medical Research Council grading scale (0 to 5 points, with 5 indicating normal function). Change from baseline values >0 represent improvement.

Muscle strength was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 35 subjects in the Treatment Continued Group and 15 subjects in the Treatment Switched Group.

Physical Function Short Form 20a (v2.0) consisted of 20 questions. The first 14 questions were each scored on a scale from 1 to 5 as follows: 1 = unable to do; 2 = with much difficulty; 3 = with some difficulty; 4 = with a little difficulty; 5 = without any difficulty; the next 6 questions were each scored on a scale from 1 to 5 as follows: 1 = cannot do; 2 = quite a lot; 3 = somewhat; 4 = very little; 5 = not at all. The total score was calculated by summing up scores (1 to 5) across all items. Total scores range from 20 to 100. A higher score represented a better outcome.

PROMIS-Physical Function was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 42 subjects in the Treatment Continued Group and 19 subjects in the Treatment Switched Group.

Fatigue Short Form 8a consisted of 6 questions, each scored on a scale from 1 to 5 as follows: 1 = not at all; 2 = a little bit; 3 = somewhat; 4 = quite a bit; 5 = very much; and 2 questions, each scored on a scale from 1 to 5 as follows: 1 = never; 2 = rarely; 3 = sometimes; 4 = often; 5 = always. The total score was calculated by summing up scores (1 to 5) across all items resulting in a total score range from 6 (minimum) to 30 (maximum). A lower score represented lower fatigue symptoms.

PROMIS-Fatigue was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 42 subjects in the Treatment Continued Group and 19 subjects in the Treatment Switched Group.

The GSGC consisted of a 10-meter walk for evaluation of gait, a 4-stair climb, Gowers' maneuver, and arising from a chair. Results of the GSGC included the time required to complete the individual tests, individual scores for each of the tests (1 to 7 points for each of gait, 4-stair climb, and Gowers' maneuver, and 1 to 6 points for arising from a chair), and a total score. GSGC total score was the sum of the component scores from the 4 functional tests. The total score ranged from a minimum of 4 points (normal performance) to a maximum of 27 points (worst performance).

GSGC was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 33 subjects in the Treatment Continued Group and 14 subjects in the Treatment Switched Group.

The EuroQol 5 Dimensions 5 Levels (EQ-5D-5L) questionnaire comprises 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has 5 levels: Level 1=no problems, Level 2=slight problems, Level 3=moderate problems, Level 4=severe problems, and Level 5=extreme problems. In this categorical assessment, subjects were asked to indicate their health state by ticking the box next to the most appropriate statement in each of the 5 dimensions.

Outcomes for change from baseline at Week 208 include 'no change', 'worsening' relative to baseline category, or 'improvement' relative to baseline category. Changes (worsening or improvement) are shown by magnitude of change (how many Levels) in each categorical assessment.

EQ-5D-5L was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 42 subjects in the Treatment Continued Group and 19 subjects in the Treatment Switched Group.

The Subject's Global Impression of Change overall physical well-being (question 1) is scored on a 7-point rating scale ranging from "very much worse" to "very much improved."

The SGIC was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 42 subjects in the Treatment Continued Group and 19 subjects in the Treatment Switched Group.

The Physician's Global Impression of Change (PGIC) is designed to record the physician's assessment of the subject's status, taking into account the subject's signs and symptoms and other neuromuscular symptoms, and signs relative to their status at the Baseline Visit. The PGIC is based on a single item that is scored on a 7-point rating scale ranging from 1 "very much worse" to 7 "very much improved."

The PGIC was evaluated using the Full Analysis Set (consisting of subjects in the study who had both a valid baseline and at least 1 post-baseline assessment for at least 1 of the main efficacy endpoints). Baseline and Month 208 assessment available for 40 subjects in the Treatment Continued Group and 19 subjects in the Treatment Switched Group.

Percent change from baseline to Week 208 in the levels of biomarker creatine kinase (CK)

The Full Analysis Set was used in analyses of biomarkers. A total of 40 subjects in the Treatment Continued Group and 18 subjects in the Treatment Switched Group had CK values at Week 208.

Percent change from baseline to Week 208 in the levels of biomarker urine Hex4.

The Full Analysis Set was used in analyses of biomarkers. A total of 39 subjects in the Treatment Continued Group and 17 subjects in the Treatment Switched Group had urine hex4 values at Week 208.

Immunogenicity was assessed by the number (%) of subjects with positive specific anti-cipaglucosidase antibodies at baseline and at Week 208

In the Treatment Continued group, 76 subjects had immunogenicity data at baseline, and 41 subjects had data at Week 208. In the Treatment Switched group, 36 subjects had immunogenicity data at baseline and 20 subjects had data at Week 208.