Motor neuron disease (MND is a progressive and fatal disease. The urinary neurotrophin receptor p75 extracellular domain (p75ECD) has previously been reported as a potential disease biomarker.

This study measured urinary p75ECD using an enzyme-linked immunoassay and normalised the results against urinary creatinine. Participants were recruited via the Multicentre Biomarker Resource Strategy in ALS (AMBroSIA) programme. Study participants included 97 MND patients, 24 of whom were studied longitudinally, and 27 healthy controls. The longitudinal changes in disease severity and survival in com- parison to urinary p75ECD were examined using mixed-model analysis on SPSS.

Confirming previous findings, urinary p75ECD levels were significantly higher in patients with MND (median 6.78ng/mg) compared to controls (4.57ng/mg) at first study visit (p=0.013). There was a significant negative correlation between ALSFRS-R rating and p75ECD levels (p=<0.001), indicating that an increase in the severity of motor neuron injury correlated with an increase in p75ECD levels. There was a significant increase in p75ECD between first and second samples in the same participants, indicating an increase in the level of this biomarker longitudinally during the disease course (p=0.011).

Urinary p75ECD is a strong candidate as a biomarker which increases with disease progression, and which has potential as a pharmacodynamic biomarker.