A Study to Assess Efficacy and Safety of Efgartigimod in Adults With Sjogren's Disease-associated Sensorimotor Polyneuropathy or Sensory Polyneuropathy (SERENITY)

Prior treatment

• Active fibromyalgia which is not adequately controlled in the judgment of the investigator, or participant is receiving fibromyalgia treatment that has not been stable treatment for at least 12 weeks before screening.
• Comorbidities (eg, asthma, chronic obstructive pulmonary disease) which have required 3 or more courses of systemic (oral, IV, or IM) glucocorticoids within the previous 12 months.

Other illness

• Besides the indication under study, known medical conditions that would interfere with an accurate assessment of clinical symptoms of SjD-associated SMPN or SPN or gangliopathy, confound the study results, or puts the participant at undue risk.
• Associated (also known as secondary) SjD, defined as overlap with another autoimmune rheumatic or systemic inflammatory condition (eg, rheumatoid arthritis, systemic lupus erythematosus, scleroderma, or idiopathic inflammatory myopathy).
• Any severe SjD manifestation or other health condition not adequately controlled at screening or baseline that may put the participant at undue risk based on the investigator's opinion.

Age

• History of malignancy unless considered cured by adequate treatment with no evidence of recurrence for ≥ 3 years; before first IMP administration.

Other

• An alternative etiology for SMPN/SPN/sensory ganglionopathy or insufficient evidence of the diagnosis.

• Is at least 18 years of age and the local legal age of consent for clinical studies when signing the ICF
• Meets the following SjD criteria: Fulfilled American College of Rheumatology and the European Alliance of Associations for Rheumatology classification 2016 SjD criteria before screening; Moderate-to-severe disease defined as a ESSDAI ≥ 5 or clinESSDAI ≥ 6 with PNS domain score of ≥ 5 (ie, a score of at least low activity) at screening; Anti-Ro/SS-A positive at a central laboratory at screening
• Meets the following SjD-associated polyneuropathy criteria: Diagnosis of SjD-associated SMPN, SPN or sensory ganglionopathy, with neuropathy duration ≤ 5 years at screening and signs of active neuropathic disease development within the last 12 months; patients with co-existing SjD-associated small fiber neuropathy are eligible; No alternative diagnosis of neuropathy etiology; Total mTCNS ≥ 6 at screening; mTCNS sensory test score \<level 3 at screening (does not apply to sensory ganglionopathy cohort where any severity is acceptable)