Table 1.
Clinical characteristics, diagnostic findings, management, and outcomes of ICI-related MG in the whole cohort (n = 65) and in the MD Anderson Cancer Center patients (n = 14)a
| Variable | Total Cohort (n = 65); n (%) | MDACC (n = 14); n (%) |
|---|---|---|
| MGFA classification | ||
| I | 8 (12) | 1 (7) |
| II | 14 (22) | 5 (36) |
| III | 8 (12) | 0 |
| IV | 4 (6) | 0 |
| V | 29 (45) | 7 (50) |
| Clinical presentation | ||
| Ptosis | 49 (75) | 11 (79) |
| Dyspnea | 40 (62) | 10 (71) |
| Limb weakness | 36 (55) | 7 (50) |
| Dysphagia | 31 (48) | 7 (50) |
| Diplopia | 27 (42) | 4 (29) |
| Neck weakness | 22 (34) | 5 (36) |
| Myalgias | 13 (20) | 4 (29) |
| Dysarthria | 8 (12) | 3 (21) |
| Facial weakness | 8 (12) | 3 (21) |
| Blurry vision | 7 (11) | 4 (29) |
| Dysphonia | 7 (11) | 4 (29) |
| Generalized weakness | 6 (9) | 2 (14) |
| Nasal speech/weakness of the palatal muscles | 6 (9) | 1 (7) |
| Incontinence | 2 (3) | 1 (7) |
| Diagnostic tools | ||
| Auto antibody panel positive titers | ||
| Anti-AChR | 37/56 (66) | 5/10 (50) |
| Anti-Striated muscle | 12/18 (67) | 6/9 (67) |
| Muscle enzymes elevation | ||
| CPK | 41/49 (84) | 9/10 (90) |
| Troponin | 13/14 (93) | 6/7 (86) |
| Edrophonium test positive | 4/5 (80)b | 0 |
| Ice pack test positive | 2/4 (50)b | 0 |
| Electrodiagnostic studies (skeletal muscle EMG, RNS, NCS) | ||
| MG | 16/37 (43)c | 3/9 (33) |
| Myopathy | 6/37 (16)d | 2/9 (22) |
| MG and myopathy | 6/37 (16)d | 4/9 (44) |
| Polyneuropathy | 3/37 (8) | 0/9 |
| No pathologic findings | 6/37 (16) | 0/9 |
| Treatment of MG | ||
| Corticosteroids | 59/63e (94) | 13/13 (100) |
| Acetylcholinesterase inhibitors | 32/63e (51) | 7/13 (54) |
| IVIG | 30/63e (48) | 9/13 (69) |
| Plasmapheresis | 28/63e (44) | 8/13 (62) |
| Other IST (MMF, rituximab, infliximab or tacrolimus) | 10/63e (16) | 6/13 (46) |
| IA | 1/63e (2) | 1/13 (8) |
| ICI holding/discontinuation | 61/63e (97) | 12/13 (92) |
| MG outcome | ||
| Complete resolution | 12/62e,f (19) | 6/13 (46) |
| Improvement | 34/62e,f (55) | 5/13 (39) |
| Deterioration | 16/62e,f (26) | 2/13 (15) |
| Death | 24 (37) | 5/14 (36) |
| MG complications | 15 (23)g | 3/14 (21) |
| Cancer progression | 4 (6) | 2/14 (14) |
| Other comorbidities | 3 (5)h | 0 |
| Unspecified | 2 (3) | 0 |
aAbbreviations: MDACC MD Anderson Cancer Center, MGFA Myasthenia Gravis Foundation of America, Anti-AChR Anti-Acetylcholine receptor, CPK creatine phosphokinase, EMG electromyography, RNS repetitive nerve stimulation, NCS nerve conduction study, MG myasthenia gravis, IVIG intravenous immunoglobulin, IST immunosuppressive therapy, MMF mycophenolic acid, IA immunoadsorption, ICI immune checkpoint inhibitor. Numbers are rounded to the nearest whole number
bOne patient had a partially positive test result
cThree patients also had findings suggestive of polyneuropathy
dTwo patients also had findings suggestive of polyneuropathy
eTwo patients with pre-existing MG did not develop a flare of their disease after ICI initiation and were excluded from the analysis
fData were not reported for one patient
gTwelve patients died from respiratory failure, one patient died from hospital acquired pneumonia following hospitalization and two others died from worsening general status from severe dysphagia
hOne patient died following acute hypercapnic respiratory failure unrelated to MG according to the authors, one patient died from complications of a preexisting heart disease and one patient died from aspiration pneumonia 1 month after discharge