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 atrophyparkinsonian type (MSA-P) or multiple system atrophy cerebellar type (MSA-C), orclinically 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/orcerebellar) within 5 years prior to the Screening Visit in the judgement of theinvestigator.

• The participant has an anticipated survival of >3 years, in the opinion of theinvestigator, at the Screening Visit.

• The participant has suitable peripheral venous access for investigational medicinalproduct (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 thatproduct, 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 byother 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/or history of any clinically significant disease or condition other than MSA,that is, in the investigator's opinion, likely to affect CNS functioning, e.g.,serious neurological disorder, other intracranial or systemic disease.

• The participant has a current diagnosis of movement disorders that could mimic MSA,e.g., Parkinson's disease, dementia with Lewy bodies, essential tremor, progressivesupranuclear palsy, spinocerebellar ataxia, spastic paraparesis, corticobasaldegeneration, or vascular, pharmacological, or post-encephalitic parkinsonism, perinvestigator discretion. Participants who have previously been incorrectly diagnosedwith Parkinson's disease will not be excluded.

Other protocol-defined inclusion and exclusion criteria apply.