A Trial of Amlenetug (Lu AF82422) in Participants With Multiple System Atrophy (MSA)

Key Inclusion Criteria: * The participant has a diagnosis of clinically established multiple system atrophy parkinsonian type (MSA-P) or multiple system atrophy cerebellar type (MSA-C), or clinically probable MSA-P or MSA-C, according to the 2022 Movement Disorders Society (MDS) criteria for the diagnosis of MSA at the Screening Visit. * The participant had onset of motor MSA symptoms (that is, parkinsonian and/or cerebellar) within 5 years prior to the Screening Visit in the judgement of the investigator. * The participant has an anticipated survival of \>3 years, in the opinion of the investigator, at the Screening Visit. * The participant has suitable peripheral venous access for investigational medicinal product (IMP) administration and blood sampling. * The participant has an UMSARS Part I score ≤16 (omitting item 11 on sexual function) at the Screening Visit. Exclusion Criteria: * The participant has previously been dosed with amlenetug. * The participant has taken any active IMP within 3 months or 5 half lives of that product, whichever is longer, prior to the first dose of IMP. * The participant has 2 or more first degree relatives with a history of MSA. * The participant, if of MSA-P subtype, has unexplained anosmia (not explained by other common causes such as allergic rhinitis or smoking, nasal structural lesions, or nasal surgery) on olfactory testing at the Screening Visit. * The participant has evidence (clinically or on magnetic resonance imaging (MRI)) and/…