Treatment of acquired autoimmune myasthenia gravis: Where are we today?

Abstract

Acquired autoimmune myasthenia gravis (MG) is a prototype of autoimmune disease in which autoantibodies directed against various antigens of the neuromuscular junction, leading to impaired neuromuscular transmission with clinical presentation of fluctuating weakness and excessive fatigue of transverse striated skeletal muscles. In 85% of patients with MG there are antibodies to the nicotine acetylcholine receptor of the postsynaptic muscle membrane (nAChR), in 5-8% of patients there are antibodies to muscle-specific tyrosine kinase (MuSK), in 1-2% of antibodies to low-density lipoprotein receptor-related protein 4 (LRP4), while in the remaining 10% none of the mentioned autoantibodies can be detected, and these patients are classified in the group of so-called "seronegative" MG. It is well known that this antigenic specificity affects both the clinical presentation and the therapeutic response, course and prognosis of the disease, which is why the early serological confirmation of the diagnosis is important. In this way, determining the exact profile of autoantibodies can provide a significantly more efficient, personalized therapeutic approach for each patient, and thus improve the prognosis and quality of life of these patients. In general, when a patient is diagnosed with MG, the goal is to alleviate the symptoms of the disease as soon as possible, as well as to induce remission or minimal manifestations of the disease in the following period. MG therapy can be roughly divided into symptomatic therapy, which includes drugs that alleviate the symptoms of weakness and fatigue, causal therapy, which immunomodulates the pathogenetic process that affects the course of MG and temporary therapeutic procedures to achieve rapid improvement in patients to avoid or treatment of the most severe clinical manifestations, the so-called "crisis" of MG. Symptomatic MG therapy involves the use of acetylcholinesterase inhibitors, represented by pyridostigmine bromide. It works by relieving the symptoms of MG in a short period of time, 4-8 hours. Causal therapy acts on the pathogenetic process on the basis of MG and it includes corticosteroids as first-line drugs and immunosuppressive drugs: azathioprine, cyclosporine A, mycophenolate mofetil, etc, while temporary therapeutic procedures include therapeutic plasma changes and intravenous immunoglobulins. All the above mentioned MG therapies are is effective in most patients with this disease, but it should be emphasized that, on the one hand, to achieve its full effect usually takes several months, and on the other hand, that such prolonged therapy is often followed by the occurrence of various side effects that require its reduction or complete cessation. With advances in immunology, molecular biology, and rapid drug development, new agents are being developed today that have much more selective immune targets, save the rest of the immune system, have lower toxicity, and a much faster onset of action MG. Some of these drugs are already being used successfully today, but we can freely say that the door to highly selective immunotherapy in MG has just been opened and that this is certainly the therapy of the future.