Case Report: A False Negative Case of Anti-Yo Paraneoplastic Myelopathy

The development of autoimmune antibody panels has improved the diagnosis of paraneoplastic neurological disorders (PNDs) of the brain and spinal cord. Here, we present a case of a woman with a history of breast cancer who presented with a subacute sensory ataxia that progressed over 18 months. Her examination and diagnostic studies were consistent with a myelopathy. Metabolic, infectious, and autoimmune testing were non-diagnostic. However, she responded to empirical immunosuppression, prompting further workup for an autoimmune etiology. An unbiased autoantibody screen utilizing phage display immunoprecipitation sequencing (PhIP-Seq) identified antibodies to the anti-Yo antigens cerebellar degeneration related protein 2 like (CDR2L) and CDR2, which were subsequently validated by immunoblot and cell-based overexpression assays. Furthermore, CDR2L protein expression was restricted to HER2 expressing tumor cells in the patient's breast tissue. Recent evidence suggests that CDR2L is likely the primary antigen in anti-Yo paraneoplastic cerebellar degeneration, but anti-Yo myelopathy is poorly characterized. By immunostaining, we detected neuronal CDR2L protein expression in the murine and human spinal cord. This case demonstrates the diagnostic utility of unbiased assays in patients with suspected PNDs, supports prior observations that anti-Yo PND can be associated with isolated myelopathy, and implicates CDR2L as a potential antigen in the spinal cord.

Paraneoplastic neurological syndromes: clinical presentations and management

We provide an overview of the varied presentations of paraneoplastic neurological syndromes. We also review the onconeural antibodies and their particular oncological and neurological associations. Recognition of these syndromes and their oncological associations is crucial, as early diagnosis and management has been associated with better patient outcomes. Specific management strategies and prognosis vary widely depending on the underlying etiology. An understanding of the relevant clinical details, imaging findings, and other diagnostic information can help tailor treatment approaches. We provide an outline of the diagnostic evaluation and treatment of various paraneoplastic neurological disorders, presenting with central and/or peripheral nervous system involvement. We briefly discuss neurologic immune checkpoint inhibitor-related adverse events, which can occasionally present with paraneoplastic neurological syndrome phenotypes.

High-resolution epitope mapping of anti-Hu and anti-Yo autoimmunity by programmable phage display

Paraneoplastic neurological disorders are immune-mediated diseases understood to manifest as part of a misdirected anti-tumor immune response. Paraneoplastic neurological disorder-associated autoantibodies can assist with diagnosis and enhance our understanding of tumor-associated immune processes. We designed a comprehensive library of 49-amino-acid overlapping peptides spanning the entire human proteome, including all splicing isoforms and computationally predicted coding regions. Using this library, we optimized a phage immunoprecipitation and sequencing protocol with multiple rounds of enrichment to create high-resolution epitope profiles in serum and cerebrospinal fluid (CSF) samples from patients suffering from two common paraneoplastic neurological disorders, the anti-Yo (n = 36 patients) and anti-Hu (n = 44 patients) syndromes. All (100%) anti-Yo patient samples yielded enrichment of peptides from the canonical anti-Yo (CDR2 and CDR2L) antigens, while 38% of anti-Hu patients enriched peptides deriving from the nELAVL (neuronal embryonic lethal abnormal vision like) family of proteins, the anti-Hu autoantigenic target. Among the anti-Hu patient samples that were positive for nELAVL, we noted a restricted region of immunoreactivity. To achieve single amino acid resolution, we designed a novel deep mutational scanning phage library encoding all possible single-point mutants targeting the reactive nELAVL region. This analysis revealed a distinct preference for the degenerate motif, RLDxLL, shared by ELAVL2, 3 and 4. Lastly, phage immunoprecipitation sequencing identified several known autoantigens in these same patient samples, including peptides deriving from the cancer-associated antigens ZIC and SOX families of transcription factors. Overall, this optimized phage immunoprecipitation sequencing library and protocol yielded the high-resolution epitope mapping of the autoantigens targeted in anti-Yo and anti-Hu encephalitis patients to date. The results presented here further demonstrate the utility and high-resolution capability of phage immunoprecipitation sequencing for both basic science and clinical applications and for better understanding the antigenic targets and triggers of paraneoplastic neurological disorders.

Exploration of Anti-Yo and Anti-Hu paraneoplastic neurological disorders by PhIP-Seq reveals a highly restricted pattern of antibody epitopes

Paraneoplastic neurological disorders (PNDs) are immune-mediated diseases of the nervous system understood to manifest as part of a misdirected anti-tumor immune response. Identifying PND-associated autoantibodies and their cognate antigens can assist with proper diagnosis and treatment while also enhancing our understanding of tumor-associated immune processes, triggers for autoimmune disease, and the functional significance of onconeuronal proteins. Here, we employed an enhanced version of phage display immunoprecipitation and sequencing (PhIP-Seq) leveraging a library of over 731,000 unique phage clones tiling across the entire human proteome to detect autoantibodies and create high-resolution epitope profiles in serum and CSF samples from patients suffering from two common PNDs, the anti-Yo (n = 36 patients) and anti-Hu syndromes (n = 44 patients). All patient samples positive for anti-Yo antibody by a validated clinical assay yielded polyspecific enrichment of phage presenting peptides from the canonical anti-Yo (CDR2 and CDR2L) antigens, while 38% of anti-Hu patients (17/44) had a serum and/or CSF sample that significantly enriched peptides deriving from the ELAVL family of proteins, the anti-Hu autoantigenic target. The anti-Hu antibodies showed a remarkably convergent antigenic signature across 15/17 patients corresponding to residues surrounding and including the degenerate motif, RLDxLL, shared by ELAVL2, 3 and 4. Lastly, PhIP-Seq identified several known and novel autoantigens in these same patient samples, representing potential biomarkers that could aid in the diagnosis and prognosis of PND and cancer.

Management of Immune-Mediated Paraneoplastic Neurological Disorders

Paraneoplastic neurological disorders are rare and clinically heterogeneous diseases. They can affect both the central and peripheral nervous system as well as the neuromuscular junction and muscle. Neurological deficits develop in 2/3 of cases prior to cancer diagnosis. The diagnostic approach includes screening for antineuronal antibodies and a search for the underlying tumor. A prompt tumor therapy in combination with immunotherapy is the cornerstone in the management of these diseases. Due to lack of clinical trials, treatment recommendations are based on case series and expert opinions. High-dose corticosteroids, intravenous immunoglobulins and apheresis therapies are often used in the acute stage of the disease. These therapies should be started as early as possible, e. g., during tumor screening, in order to prevent irreversible damage. Long-term treatment is mostly immunosuppressive and depends on the specific paraneoplastic syndrome. Outcomes vary depending upon the prognosis of the underlying cancer and the nature of the antineuronal antibodies. Disorders with antibodies directed against antigens on the neuronal cell surface are highly sensitive to B cell-directed therapies and mostly associated with a favorable outcome. A thorough review of published data on actual treatment recommendation is provided along with discussion of currently not validated, but potentially effective new therapies.

Paraneoplastic Neurological Disorders

Paraneoplastic neurological disorders (PNDs) are estimated to affect approximately 0.01% of all patients with cancer. The majority of PNDs are thought to be the byproduct of immune-mediated processes directed against tumor-related antigens, processes which are sometimes effective against a systemic cancer. The inciting cancer is often asymptomatic or occult, with patients presenting to the neurologist with a variety of neurological symptoms and signs depending on the area(s) of the central, peripheral, and autonomic nervous system involved. The diagnosis of a PND is reserved for patients with histologically proven cancer; however, clinical presentation and diagnostic test results may make the diagnosis of a PND highly probable in the absence of the diagnosis of a cancer.