Lupus Science & Medicine
Table 1 Patient baseline demographics and disease characteristics Pooled placebo (n=5)
Mezagitamab 45mg (n=6)
Mezagitamab 90mg (n=6)
Mezagitamab 135mg (n=5)
Age, years (SD) Sex, female, n (%)
36.4 (6.6)
51.0 (22.0)
46.7 (6.5)
49.6 (13.5)
5 (100)
6 (100)
5 (83.3)
4 (80)
Baseline weight, kg, mean (SD)
87.3 (17.7)
75.0 (18.4)
85.6 (28.4)
64.6 (8.16)
Ethnicity, n (%)
Hispanic or Latino
1 (20) 4 (80)
2 (33.3) 4 (66.7)
0
1 (20) 4 (80)
Non-Hispanic and Latino
6 (100)
Race, n (%)*
American Indian
0 0
0 0
0 0
1 (20) 1 (20) 2 (40) 1 (20)
Asian
Black or African American
2 (40) 3 (60)
4 (66.7) 2 (33.3)
1 (16.7) 4 (66.7) 1 (16.7)
White
Multiracial
0
0
0
SLEDAI-2K at baseline, mean (SD) CLASI at baseline, mean (SD)
8.4 (1.67) 4.8 (4.76)
9.7 (4.27) 7.2 (5.81)
9.7 (3.67) 5.2 (4.62)
8.8 (1.79)
11.8 (11.37)
SLE background treatment Antimalarials, n (%)
4 (80.0) 3 (60.0) 1 (20.0) 3 (60.0) (8.3) 3 (60.0)
5 (83.3) 3 (50.0) 2 (33.3) 2 (33.3) (10) 2 (33.3)
6 (100) 4 (66.7) 2 (33.3) 2 (33.3) (7) 1 (16.7) 1 (16.7) 1 (16.7)
4 (80.0) 3 (60.0) 1 (20.0) 3 (60.0) (4.7) 3 (60.0)
Hydroxychloroquine
Hydroxychloroquine sulphate
Corticosteroids, n (%)(mean dose (mg))
Prednisone
Methylprednisolone Mycophenolate, n (%)
0
0
0
1 (20.0) 1 (20.0)
2 (33)
3 (60.0) 2 (40.0)
Mycophenolate mofetil Mycophenolate sodium
1 (16.7)
0
0 0
0
1 (16.7)
0
Mycophenolic acid Methotrexate, n (%)
1 (16.7) 2 (33.3)
0 0
1 (20.0)
1 (20.0)
0
*Subject may have more than one race. Those subjects selecting multiple races are counted only under ‘multiracial’. CLASI, Cutaneous Lupus Erythematosus Disease Area and Severity Index; SLE, systemic lupus erythematosus; SLEDAI-2K, SLE Disease Activity Index 2000.
including the COVID-19 pandemic and protocol pre- specified dose holds for safety. Overall, mezagitamab was well tolerated, with no safety concerns identified during the study. There were no substantial imbalances in treatment emergent AEs (TEAEs) across treatment groups (table 2). One patient in each treatment group experienced at least one drug- related TEAE, as determined by the investigator; these included urinary tract infection, nausea, fever and rash. All TEAEs observed in the study had a maximum intensity of grade 1 or grade 2 based on Common Terminology Criteria for Adverse Events. There were two treatment- emergent serious AEs with mezagatimab: palpitations (1 patient in 45 mg group) and dyspnoea (1 patient in 135 mg group; led to study drug withdrawal); neither were considered related to mezagitamab. No cytokine release syndrome events or injection site reaction TEAEs
were reported. There was one report of hypersensi- tivity reaction in the mezagitamab 135 mg group, which consisted of fever with onset on the first administration of study drug and resolved within 1 day. No remarkable findings for laboratory tests, ECGs, vital signs or physical examinations were reported that were related to mezagi- tamab treatment. There were no trends for increased safety-related dose holds or lower treatment compliance among mezagitamab-treated groups, as only one TEAE (dyspnoea) led to drug discontinuation in the 135 mg group (described above). Efficacy An exploratory objective of this study was to assess the effects of mezagitamab on disease activity using SLE disease activity instruments. At baseline, the mean SLEDAI-2K total scores were similar in the placebo (8.4),
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McDonnell SRP, et al . Lupus Science & Medicine 2024; 11 :e001112. doi:10.1136/lupus-2023-001112
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