A new study reports that patients with thymoma-associated myasthenia gravis (MG) who also have immunodeficiency are at an elevated risk of infection and require additional vigilance during follow-up.
The study, published in the Journal of Neuroimmunology, notes that efgartigimod, a new treatment for MG, can lead to hypogammaglobulinemia, which underscores this risk.
“Efgartigimod can decrease the levels of pathogenetic autoantibodies in MG serum by inhibiting the [immunoglobulin G (IgG)] recycling process and provide favorable responses in MG patients irrespective of their autoantibody profiles,” the authors wrote. “Since efgartigimod induces hypogammaglobulinemia, there may be a considerable risk of infectious diseases among MG patients treated with this agent.”
The research team evaluated 664 Japanese patients with MG at a single center between January 2000 and December 2020. Of these, 132 had thymoma, and 9 of these patients had immunodeficiency at some point, with below-normal serum IgG levels in 5 patients. Patients with thymoma-associated MG and immunodeficiency presented with concomitant autoimmune disorders, invasive thymoma, severe pneumonia, higher C4 concentrations, and decreased IgG levels. Eight patients died due to severe infection.
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The authors suspect that the 5 patients with hypogammaglobulinemia were particularly vulnerable to infection, given their shorter interval between immunodeficiency onset and death. However, they note that confounding factors such as age, underlying disease, and immunotherapy could have also affected the patients’ vulnerability to infection.
The authors conclude that patients with thymoma-associated MG and immunodeficiency represent a specific subset of MG patients with additional follow-up requirements. Due to the increased risk of bacterial, fungal, viral, and opportunistic infections, the authors recommend vigilance in patients with MG who are treated with immunosuppressive agents and the consideration of immunoglobulin replacement treatment to reduce these risks.
Ishizuchi K, Takizawa T, Ohnuki Y, et al. Immunodeficiency in patients with thymoma-associated myasthenia gravis. J Neuroimmunol. Published online August 12, 2022. doi:10.1016/j.jneuroim.2022.577950