Open-Label Efficacy and Safety Study of Pozelimab in Patients With CD55-Deficient Protein-Losing Enteropathy (CHAPLE Disease)

Normalization of serum albumin was defined as serum albumin within the normal range at least 70 percent (%) of measurements between weeks 12 and 24, and no single albumin measurement of <2.5 grams per deciliter (g/dL) between weeks 12 and 24, and no requirement for albumin infusion between weeks 12 and 24. Improvement in the following 4 prespecified clinical outcomes that were evaluable for improvement at baseline, without worsening of the others: Daily bowel movement frequency, the presence and severity of facial edema (physician-reported), the presence and severity of peripheral edema (physician-reported), and the participant/caregiver assessment of frequency of problematic abdominal pain. Percentage of participants with active disease at baseline who achieved normalization of serum albumin and improvement in prespecified clinical outcomes at Week 24 were reported.

TEAEs are defined as AEs that developed or worsened during the on-treatment period. The on-treatment period is defined as the time from first dose of investigational product up to 21 weeks after the last dose of investigational product. Severity of TEAEs was graded according to the following scale: Mild: Does not interfere in a significant manner with the patient's normal functioning level, Moderate: Produces some impairment of functioning but is not hazardous to health and Severe: Produces significant impairment of functioning or incapacitation and is a definite hazard to the participants health.

Improvement in most bothersome sign/symptom determined using semi-structured concept elicitation interview, from 'core' clinical endpoints of frequency of bowel movements, peripheral edema, facial edema, abdominal pain frequency, nausea, vomiting, stool consistency.

Daily bowel movements captured by e-diary. The number of bowel movements per day was calculated each week of the study. It was based on a 1-week average and calculated as the sum of the number of bowel movements in a given week divided by the number of days with non-missing bowel movement frequency data. If more than 3 days of bowel movement data was missing in a given week, bowel movement frequency data was considered missing for that week.

The number of days per week with >=1 loose/watery bowel movement, is calculated each week of the study as the sum of the number of days with >=1 loose/watery bowel movement in a given week divided by the number of days with non-missing stool consistency data and then multiplied by 7, is presented. If more than 3 days of stool consistency data was missing in a given week, stool consistency data was considered missing for that week.

The measurement of abdominal ascites (excess abdominal fluid) was based on abdominal circumference. Abdominal circumference was measured regardless of the physician's assessment of the presence or absence of ascites.

Blood samples were collected from participants at defined time points for the assessment of albumin. Absolute value of albumin at specified timepoints was reported.

Blood samples were collected from participants at defined time points for the assessment of protein and IgG. Absolutes values of protein and IgG measured as g/L at baseline and Week 24 was reported.

Blood samples were collected from participants at defined time points for the assessment of Ig, IgM and IgA. Absolute value of Ig, IgM and IgA measured as mg/dL at baseline and Week 24 was reported.

Blood samples were collected from participants at defined time points for the assessment of vitamin B12. Absolute values of vitamin B12 at baseline and Week 24 was reported.

Blood samples were collected from participants at defined time points for the assessment of iron indices. Absolute values of unsaturated iron and unsaturated iron binding capacity measured as micromoles per liter (mcmol/L) at baseline and Week 24 was reported.

Absolute Values of Vitamin B9 - Central Lab

Blood samples were collected from participants at defined time points for the assessment of iron indices. Absolute values of ferritin was reported.

Blood samples were collected from participants at defined time points for the assessment of magnesium, total cholesterol, and triglycerides. Absolute values of magnesium, total cholesterol, and triglycerides measured as mmol/L at baseline and Week 24 was reported.

Measured by normalization of serum albumin, no worsening of facial or peripheral edema, increase in bowel movement, or increase in abdominal pain frequency, no increase in dose of permitted concomitant medication for the treatment of PLE at any time as described in the protocol

The physician assessment of facial edema is based on a 5-point Likert scale ranging from no edema (1) to very severe edema (5).

The physician assessment of peripheral edema is based on a 5-point Likert scale ranging from no edema (1) to very severe edema (5).

Frequency of limitations is assessed on a 5-point Likert response scale, ranging from never a problem (0) to almost always a problem (4). Items were reverse scored and linearly transformed to a 0 to 100 scale, where lower scores indicate more frequent problems with food and drink limitations.

Physical functioning, emotional functioning, social functioning, and school/work/studies functioning is assessed using a 5-point Likert scale, ranging from never a problem (0) to almost always a problem (4). Items were reverse-scored and linearly transformed to a 0 to 100 scale, with higher scores indicating better HRQoL. The total scale score is computed as the sum of all the items over the number of items answered on individual scales. Subscale score is calculated as the sum of the items in the scale divided by the number of items answered in the scale.

Weight-for-age z-score compares a participant's weight to children of the same age and sex from a healthy reference population. A z-score reflects an individual score as compared to a population mean and is expressed in units of standard deviation above (positive values) and below (negative values). Body weight z-score, regardless of magnitude, represents catch-up growth.

Height-for-age z-score compares a participant's height to children of the same age and sex from a healthy reference population. A z-score reflects an individual score as compared to a population mean and is expressed in units of standard deviation above (positive values) and below (negative values). Any increase in height z-score, regardless of magnitude, represents catch-up growth.