Monoclonal antibodies can block a key immune-related protein that drives the spread of brain cell damage in Parkinson's disease (PD). This protein, called glycoprotein nonmetastatic melanoma B (GPNMB), might be part of a promising strategy for developing a treatment that slows disease progression at its earliest stages, according to a study published in Neuron, by researchers at the Perelman School of Medicine at the University of Pennsylvania.