Strategic decision

The main purpose of this study is to evaluate the efficacy of AMZ002 compared to Vigabatrin in participants with newly diagnosed infantile spasms (IS).

Inclusion Criteria:

• Participant has been diagnosed with IS within 6 weeks prior to Screening. Diagnostic criteria include both clinical spasms and an EEG pattern consistent with hypsarrhythmia or significant abnormality compatible with IS
• Participant has normal renal function as defined by an estimated glomerular filtration rate (eGFR) greater than [>] 60 milliliter/minute (mL/min)/1.73 m^2, calculated as eGFR = 0.413 × (height [Centimeter (cm)]/serum creatinine [milligrams per deciliter {mg/dL}])
• Participant's legally authorized representative (that is [i.e.], parent or guardian) must provide written informed consent obtained per Institutional Review Board (IRB) policy and requirements, consistent with the International Council for Harmonisation (ICH)
• Participant's parent/guardian is able to understand and willing to comply with study procedures and restrictions

Exclusion Criteria:

• Participant has been diagnosed with tuberous sclerosis
• Participant has acute illness considered clinically significant by the Investigator within 30 days prior to Screening
• Participant has a diagnosis of recent systemic fungal infection; history of ocular herpes simplex; history of or current peptic ulcer; uncontrolled hypertension or congestive heart failure; or any other condition that would be significantly impacted by the study drug
• Participant has a preplanned surgery or procedure(s) that would interfere with the conduct of the study
• Participant has received any prior treatment for IS
• Participant has been previously treated with adrenocorticotropic hormone (ACTH), corticosteroids, or Vigabatrin for seizures;
• Participant has been previously treated with a course of corticosteroids for an indication other than seizures within 30 days prior to Screening
• Participant has a known or suspected allergy to ACTH or Vigabatrin or any component of AMZ002 or Vigabatrin
• Participant has used any other investigational drug within 30 days or 5 half-lives prior to the first dose of AMZ002 or Vigabatrin (whichever is longer)
• Participant' s parent/guardian is unable to provide written informed consent and/or to complete the daily diary
• Participant has any other disease, condition, or therapy that, in the opinion of the Investigator, might compromise safety or compliance, preclude the participant from successfully completing the study, or interfere with the interpretation of the results