SUMMARY  

• The company cannot recommend any practices, procedures, or usage of IMAAVY that deviate from the approved labeling.
• An 8-week open-label subcutaneous (SC) substudy of the VIVACITY-MG3 clinical trial is being conducted to provide additional data on the efficacy, safety, tolerability, pharmacokinetics (PK) and immunogenicity of SC IMAAVY compared to intravenous (IV) IMAAVY for the treatment of adult patients with generalized myasthenia gravis (gMG).¹ 
• The primary endpoint in the United States (US) is the percent change in anti- acetylcholine receptor (AChR) autoantibody titer from pre-first IMAAVY dose day 1 to week 8 (day 57).¹ 
• The primary endpoint for the Rest of the World (RoW) is the percent change in total immunoglobulin G (IgG) levels from pre-first IMAAVY dose day 1 to week 8 (day 57).¹ 

CLINICAL DATA

VIVACITY-MG3 SC Substudy

VIVACITY-MG3 is a 24-week, phase 3, randomized, multicenter, double-blind (DB), PBO-controlled clinical trial (NCT04951622) that evaluated the efficacy and safety of IMAAVY in adult patients with gMG.²  Patients who completed the DB phase were eligible to enter an open-label extension (OLE), where all patients received IMAAVY 15 mg/kg IV every 2 weeks (Q2W) in addition to standard of care (SOC) therapy.^1,3   

In an ongoing 8-week open-label substudy, the efficacy, PK, pharmacodynamics (PD), safety, and tolerability of SC IMAAVY will be compared to IV IMAAVY.³ 

Study Design/Methods

• The study design is presented in the Figure: VIVACITY-MG3 OLE SC Substudy Design

• The SC substudy consists of 2 cohorts, where patients received IMAAVY 518 mg SC weekly:
  • SC Cohort 1: Will include approximately 80 patients from the open-label extension (OLE) phase of the VIVACITY-MG3 (anti-AChR positive and anti-AChR negative, including seronegative) trial who meet entry criteria listed below and consent to switching to SC IMAAVY.¹ 
    • Inclusion Criteria:^1,3  
    • Reasonable abdominal skin area for SC administration.
    • Willing to maintain stable dose of corticosteroids and/or immunosuppressants during the initial 8 weeks of the substudy
    • Exclusion Criteria:^1,3 
    • Recently tapered concomitant corticosteroid (less than 4 weeks prior to SC day 1) or immunosuppressant therapy (less than 3 months prior to SC day 1)
    • Actively deteriorating at SC day 1 visit
  • SC Cohort 2: Will include approximately 20-80 patients with gMG who have not previously received treatment with IMAAVY.¹ 
    • Additional criteria to be determined at a later date.¹ 
• Patients who were randomized to the IV IMAAVY group in the double-blind phase of the VIVACITY-MG3 study will serve as the IV comparator group for the PD endpoints in this substudy.¹ 
• Patients who complete the substudy may roll over into a long-term extension (LTE) phase (up to 108 weeks) and continue to receive IMAAVY SC weekly administered either in clinic or at home by a home-healthcare provider.¹ 
• The currently available IV formulation will be administered SC in the abdomen once a week in clinic by a healthcare professional during the 8-week study period.¹ 
• Patients experiencing a clinical deterioration while on SC IMAAVY or who are unable/unwilling to roll over into the LTE of the substudy may transition back to IV IMAAVY 15 mg/kg Q2W.¹ 

Endpoints

• The primary endpoint in the US is the percent change in anti-AChR autoantibody titer from pre-first IMAAVY dose day 1 to week 8 (day 57).¹ 
• The primary endpoint for the RoW is the percent change in total IgG levels from pre-first IMAAVY dose day 1 to week 8 (day 57).¹ 
• The secondary endpoints evaluated at pre-first IMAAVY dose day 1 to week 8 (day 57) are as follows:
  • US: Percent change in total IgG levels.¹ 
  • RoW: Percent change in anti-AChR autoantibody titer.¹ 
  • ALL: Efficacy (change from baseline in clinician and patient-reported oucome measures), safety, and tolerability.¹ 

Literature Search

• A literature search of MEDLINE^®, EMBASE^®, BIOSIS Previews^®, and DERWENT^®
• (and/or other resources, including internal/external databases) was conducted on
• 26 September 2025.