I understood that the major reason for finding or establishing biomarkers is the one mentioned by Soania, that they are needed to accurately assess disease progression and provide a biological marker (aha!) against which to determine if a treatment is actually slowing or stopping progression.

Learning of the earliest biomarkers in the disease, and how they appear in the progression of the disease, will help researchers more accurately target potential remedies. As things stand right now, treatment development and assessment of efficacy is largely a shot in the dark. Whether or not a drug is said to work is based on clinical observation, without parallel determination that the biological progression of the disease has actually been altered in any way.