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Table 2 Clinical characteristics, diagnostic findings, management, and outcomes of ICI-related MG in patients with pre-existing MG (n = 13) and those with new onset disease (n = 52)a

From: Immune checkpoint inhibitor related myasthenia gravis: single center experience and systematic review of the literature

VariableNew Onset (n = 52); n (%)Pre-existing MG (n = 13); n (%)p value
Median time from ICI initiation to onset of MG symptoms (weeks)  0.27
44.7 
MGFA classification0.161
 I7 (14)1 (8) 
 II14 (27)0 
 III6 (12)2 (15) 
 IV2 (4)2 (15) 
 V23 (44)6 (46) 
Clinical presentation
 Ptosis43 (83)6 (46)0.01
 Dyspnea32 (62)8 (62)1
 Limb weakness30 (58)6 (46)0.54
 Dysphagia24 (46)7 (54)0.76
 Diplopia22 (42)5 (39)0.8
 Neck weakness20 (39)2 (15)0.19
 Myalgias13 (25)00.06
 Blurry vision7 (14)00.33
 Dysarthria6 (12)2 (15)0.65
 Generalized weakness6 (12)00.34
 Dysphonia6 (12)1 (8)1
 Facial weakness5 (10)3 (23)0.19
 Nasal speech/weakness of the palatal muscles5 (10)1 (8)1
 Incontinence2 (4)01
Diagnostic tools
 Auto antibody panel positive titers
  Anti-AChR32/50 (64)5/6 (83)0.65
  Anti-Striated muscle12/18 (67)0/0N/A
 Muscle enzymes elevation
  CPK37/44 (84)4/5 (80)1
  Troponin12/13 (92)1/1 (100)1
 Edrophonium test positive5/5 (100)0N/A
 Ice pack test positive2/4 (50)0N/A
 Electrodiagnostic studies (skeletal muscle EMG, RNS, NCS)
  MG14/34b (41)2/3 (67)0.56
  Myopathy6/34c (18)0/30.58
  MG and myopathy6/34c (18)0/30.33
  Polyneuropathy2/34 (6)1/3 (33)0.23
  No pathologic findings6/34 (18)0/30.58
Treatment of MG
  Corticosteroids48 (92)11/11d (100)1
  Acetylcholinesterase inhibitors25 (48)7/11d (64)0.35
  IVIG25 (48)5/11d (46)0.87
  Plasmapheresis22 (42)6/11d (55)0.52
  Other IST (MMF, rituximab, infliximab or tacrolimus)7 (13)3/11d (27)0.36
  IA3 (6)0/11d1
  ICI holding/discontinuation51 (98)10/11d (91)0.32
MG outcome
  Complete resolution8/51 (16)4/11d (36)e0.2
  Improvement30/51e (59)4/11d (36)0.2
  Deterioration13/51e (26)3/11d (27)1
Death21 (40)3 (23)0.34
  MG complications13 (25)2 (15)0.72
  Cancer progression4 (8)00.58
  Other comorbidities2 (4)1 (8)0.5
  Unspecified2 (4)01
  1. aAbbreviations: MG myasthenia gravis, ICI immune checkpoint inhibitor, MGFA Myasthenia Gravis Foundation of America, Anti-AChR Anti-Acetylcholine receptor, CPK creatine phosphokinase, EMG electromyography, RNS repetitive nerve stimulation, NCS nerve conduction study, IVIG intravenous immunoglobulin, IST immunosuppressive therapy, MMF mycophenolic acid, IA immunoadsorption. Numbers are rounded to the nearest whole number
  2. bThree patients also had findings suggestive of polyneuropathy
  3. cTwo patients also had findings suggestive of polyneuropathy
  4. dTwo patients with pre-existing MG did not develop a flare of their disease after ICI initiation and were excluded from the analysis
  5. eData were not reported for one patient