Anti-γ-Aminobutyric Acid Type β Receptor Antibody-Associated Encephalitis After 2 Cycles of Durvalumab Therapy in a Patient with Small Cell Lung Cancer: A Case Report

Figures & data

Table 1 Cerebrospinal Fluid Test Showed That the Anti-γ-Aminobutyric Acid Type _B Receptor (GABA_B) Antibody IgG Was Positive

Projects	Testing Method	Results	Reference Value
Autoimmune encephalitis: 12 items
Anti-glutamate receptor (NMDA type) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-glutamate receptor (AMPA1 type) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-glutamate receptor (AMPA2 type) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-leucine-rich glioma inactivating protein 1(LGI 1) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-γ-aminobutyric acid type β receptor (GABABR) antibody IgG	CBA	Positive (+) 1:100	Negative (-)
Anti-contact protein-associated protein2(CASPR2) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-Ig LON family protein 5 (IgLON5) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-dystroglycan-like protein 6 (DPPX) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-glycine receptor 1 (GlyR1) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-dopamine receptor 2 (DRD2) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-glycine receptor 1 (GlyR1) antibody IgG	CBA	Negative (-)	Negative (-)
Anti-glutamic acid decarboxylase 2 (GAD65) antibody IgG	CBA	Negative (-)	Negative (-)
Antimetabolic glutamate receptor 5 (mGluR5) antibody IgG	CBA	Negative (-)	Negative (-)

Abbreviations: Anti-GABA_BR, anti-γ-aminobutyric acid type β receptor; AE, Autoimmune encephalitis; CNS, central nervous system; SCLCS, small cell lung cancer; ICIs, immune checkpoint inhibitors; irAEs, immune-related adverse events; MRI, magnetic resonance imaging; CTLA-4, cytotoxic T-lymphocyte-associated antigen 4; PD-1, programmed cell death protein 1; PD-L1, programmed cell death ligand 1; NAEs, neurological adverse events; LEMS, Lambert–Eaton myasthenic syndrome; FLAIR/T2, fluid-attenuated inversion recovery-T2 weighted.

Figure 1 (A1 and A2) The baseline CT scan of the patient’s chest in August 2020. (B1 and B2) CT scan of the chest after two cycles of durvalumab in October 2020.

Figure 2 (A1 and A2) The baseline MRI scan of the patient’s head in August 2020. (B1 and B2) MRI scan of the head after the first seizure in October 2020. (C1 and C2) MRI scan of the head after the second seizure.

Figure 3 (A1 and A2) The result of the lump in the left lung pathological histopathology and immunohistochemistry by local bronchoscopy biopsy performed showed that is small-cell endocrine cancer.

Figure 4 (A1 and A2) PETCT on August 27, 2020; The increased mass of FDG metabolism in the hyperplastic block indicated by the arrow.

Figure 5 (A) The patient’s EEG after the first seizure in October 2020. (B) The patient’s EEG after the second seizure in October 2020. The pink box showed EEG becomes abnormal situation with sharp and slow waves.