Leukaemia in children - what do these studies have to do with the use of Cladribine (2-chlorodeoxyadenosine) in pwMS?
Well, they revealed over 20 years ago that Cladribine penetrates into the spinal fluid, and in relevant concentrations (about 1/5 - 1/4 of plasma).
Whilst this property is not unique (among drugs used for pwMS) to Cladribine, it is the only drug where its mechanism of action strongly suggests a direct effect within the central nervous system.
Penetration into the brain may be important for the mechanism by which Cladribine could potentially work not only in those recently diagnosed with MS, but also in people with advanced MS (EDSS>6): Even though at this stage there is generally less significant blood brain barrier leakage and therefore less overt entry of inflammatory cells from the blood stream into the brain, we know that inflammation plays a role throughout the disease, including its advanced stage. A drug that can attack T and B lymphocytes, and perhaps plasma cells, in the brain of pwMS directly, even without overt blood brain barrier breakdown, may be effective in preserving important functions such as upper limb strength & coordination, cognition and speech.