A Study to Test the Safety of Pozelimab in Pediatric Participants 1 to 5 Years of Age With a Rare Disease Called CHAPLE (Complement Hyperactivation, Angiopathic Thrombosis, Protein-losing Enteropathy) Disease

Key Inclusion Criteria: 1. Clinical diagnosis of CD55-deficient CHAPLE disease as described in the protocol 2. Parent(s)/legal guardian(s) are willing and able to comply with participant's clinic visits and study-related procedures, including participant's completion of the full series of meningococcal vaccinations required per protocol. 3. Parent(s)/legal guardian(s) are willing to provide written informed consent 4. Participant has active CHAPLE disease as described in the protocol Key Exclusion Criteria: 1. History of meningococcal infection 2. No documented meningococcal quadrivalent (serotype ACWY) vaccination prior to screening and participant's parent(s)/legal guardian(s) are unwilling for participant to undergo vaccination during the study as described in the protocol 3. No documented vaccination for Haemophilus influenzae and Streptococcus pneumoniae if applicable based on local practice or guidelines prior to screening as described in the protocol 4. Prior treatment with a complement inhibitor as described in the protocol 5. Presence of a concomitant disease that leads to hypoproteinemia or secondary intestinal lymphangiectasia as described in the protocol Note: Other Protocol Defined Inclusion/ Exclusion Criteria Apply