Neuromyelitis Optica (NMO)
Neuromyelitis optica (NMO, Devic’s syndrome) is an immune-mediated chronic inflammatory disease of the central nervous system (CNS). Previously considered a clinical variant of multiple sclerosis (MS), NMO is now regarded as a distinct disease entity with specific treatment requirements.
Clinically, NMO presents with severe relapsing attacks of inflammation and demyelination of the optic nerve (optic neuritis) and the spinal cord (myelitis), often characterized with poor or no recovery from resulting disabilities. While early stages of the disease commonly spare the brain, later stages can also affect the brain, although the lesions observed are discriminable from those characteristic of MS.
The characteristic symptoms of this inflammatory disease include the loss of vision and spinal cord function manifesting as:
- Varying degrees of weakness or paralysis in the legs and/or arms
- Loss of sensation (including blindness)
- Potential loss of control over bladder and/or bowel
Currently, no curative treatment is available and treatments focus on preventing the recurrence of attacks and associated disability.
The importance of early and accurate NMO diagnosis
NMO is typically diagnosed in patients who have previously suffered from at least one episode of optic neuritis and myelitis. If not treated appropriately, 50% of patients lose their vision in at least one eye or the ability to walk over the course of five years. Neurological disability caused by NMO is based on the number of attacks rather than a progressive phase of the illness. Early accurate diagnosis would help to reduce the probability of recurrent attacks and minimize resulting patient disability.
During the initial stages NMO patients can be misdiagnosed with MS because of highly similar clinical and radiological characteristics. MS is usually treated using immunomodulation therapy, which may in some cases worsen NMO. Therefore, it is critical to diagnose NMO at the early stages with high specificity and sensitivity.
Current tools for NMO diagnosis
In addition to clinical signs diagnostic tools consist of brain and spinal cord magnetic resonance imaging (MRI) to detect inflammatory lesions. Since a few years the presence of NMO IgG-antibodies in patient’s blood is routinely used as a diagnostic marker.
The blood tests detect the presence of autoantibodies against the water channel protein Aquaporin-4 (AQP4), a highly specific marker for the disease. These AQP4 IgG-autoantibodies are found in 60-70% of NMO patients. However, this implies that 30-40% of patients are missed by this test. Moreover, early on in the disease the sensitivity of the test is limited.
With the diagnostic needs of neurologists and patients in mind, we are committed to close the diagnostic sensitivity gap for NMO. Within our diagnostics pipeline is a novel biomarker panel capable of distinguishing NMO patients with and without the presence of autoantibodies against AQP4 from healthy individuals and MS patients. We are working closely with our clinical and pharmaceutical partners to bring this NMO test to market.