In general, PML has a mortality rate of 30–50% in the first few months, and those who survive can be left with varying degrees of neurological disabilities.
[1] The lesions affecting the parietal and occipital lobes of the brain can lead to a phenomenon known as alien hand syndrome.
[7] PML can still occur in people on immunosuppressive therapy, such as efalizumab, belatacept, and various transplant drugs, which are meant to weaken the immune system.
[8] After a safety review, the drug was returned to the market in 2006 as a monotherapy for MS under a special prescription program.
[11] PML is diagnosed in a patient with a progressive course of the disease, finding JC virus DNA in spinal fluid together with consistent white-matter lesions on brain magnetic resonance imaging (MRI); alternatively, a brain biopsy is diagnostic[1] when the typical histopathology of demyelination, bizarre astrocytes, and enlarged oligodendroglial nuclei are present, coupled with techniques showing the presence of JC virus.
In patients on immunosuppression, this means stopping the drugs or using plasma exchange to accelerate the removal of the biologic agent that put the person at risk for PML.
[14] A rare complication of effective HAART is immune reconstitution inflammatory syndrome (IRIS), in which increased immune system activity actually increases the damage caused by the JCV infection; although IRIS can often be managed with medication, it is extremely dangerous in PML.
[18] In June 2010, the first case report appeared of a PML patient being successfully treated with the antimalarial drug mefloquine with activity against the JC virus.
[21] A number of drugs work against JC virus in cell culture, but no proven, effective therapy is known in humans.
[25] In December 2021, Cellevolve announced it is launching a clinical trial for the treatment of PML utilizing BK virus specific T-cells (VSTs).
[26] One-third to one-half of people with PML die in the first few months following diagnosis, depending on the severity of their underlying disease.