Drug-induced progressive multifocal leukoencephalopathy: Rare but serious

Management: Stop the offending agent, restore immune function

Specific pharmacologic treatments for PML are lacking. Management of drug-induced PML starts with discontinuing the offending agent. Restoring immune function has been found to be the most effective approach to treat PML.³ Restoration is possible through interleukin-2 (IL-2), IL-7, and T-cell infusions. Other treatment options are theoretical and include the development of a JCV vaccine to stimulate host response, plasma exchange to remove the medication from the host, and antiviral therapy targeting JCV replication. Diclofenac, isotretinoin, and mefloquine can inhibit JCV replication.³

Based on the theory that JCV requires 5HT2A receptors for entry into cells, researchers have studied medications that block this receptor as a treatment for PML. The first-generation antipsychotic chlorpromazine did not show benefit when combined with cidofovir, a replication inhibitor.³ Antipsychotics agents such as ziprasidone and olanzapine have shown in vitro inhibition of JCV, while risperidone has mixed results, with 1 trial failing to find a difference on JCV in fetal glial cells.³ Second-generation antipsychotics may be the preferred option due to more potent antagonism of the 5HT2A receptors and fewer adverse effects compared to agents such as chlorpromazine.⁴ The antidepressant mirtazapine has shown to have promising results, with evidence indicating that earlier initiation is more beneficial.³ Overall, data involving the use of medications that act on the 5HT2A receptor are mixed. Recent data suggest that JCV might enter cells independent of 5HT2A receptors; however, more research in this area is needed.²

The best strategy for treating drug-induced PML has not yet been determined. While combination therapy is thought to be more successful than monotherapy, ultimately, it depends on the patient’s immune response. If a psychotropic medication is chosen as adjunct treatment for drug-induced PML, it is prudent to assess the patient’s entire clinical picture to determine the specific indication for therapy (ie, treating symptomatology or drug-induced PML).

CASE CONTINUED

Following diagnosis, Mr. P is provided supportive therapy, and his care team discontinues methotrexate and etanercept. Although data are mixed on the efficacy of medications that work on 5HT2A receptors, because Mr. P was recently diagnosed with MDD, he is started on mirtazapine 15 mg/d at night in an attempt to manage both MDD and PML. It is possible that his depressive symptoms developed as a result of drug-induced PML rather than major depressive disorder. Discontinuing methotrexate and etanercept stabilizes Mr. P’s PML symptoms but leads to an exacerbation of his RA symptoms. Mr. P is initiated on hydroxychloroquine 400 mg/d for RA management. At a follow-up appointment 4 weeks later, Mr. P reports his sleep, concentration, and overall depressive symptoms have improved. He requests to continue taking mirtazapine.

Related Resources

• Castle D, Robertson NP. Treatment of progressive multifocal leukoencephalopathy. J Neurol. 2019;266(10):2587-2589. doi:10.1007/s00415-019-09501-y

Drug Brand Names

Abatacept • Orencia
Adalimumab • Humira
Alemtuzumab • Campath
Azathioprine • Azasan, Imuran
Basiliximab • Simulect
Belimumab • Benlysta
Bevacizumab • Avastin
Brentuximab vedotin • Adcetris
Cetuximab • Erbitux
Chlorpromazine • Thorazine, Largactil
Cidofovir • Vistide
Cladribine • Mavenclad
Cyclophosphamide • Cytoxan
Cyclosporine • Gengraf, Neoral
Dacarbazine • DTIC-Dome
Diclofenac • Cambia, Zorvolex
Dimethyl fumarate • Tecfidera
Etanercept • Enbrel
Fingolimod • Gilenya
Fludarabine • Fludara
Hydroxychloroquine • Plaquenil
Ibritumomab tiuxetan • Zevalin
Infliximab • Avsola, Inflectra
Isotretinoin • Absorica, Claravis
Mefloquine • Lariam
Methotrexate • Rheumatrex, Trexall
Mirtazapine • Remeron
Mitoxantrone • Novantrone
Muromonab-CD3 • Orthoclone OKT3
Mycophenolate mofetil • CellCept
Natalizumab • Tysabri
Nelarabine • Arranon
Obinutuzumab • Gazyva
Olanzapine • Zyprexa
Risperidone • Risperdal
Tacrolimus • Prograf
Vincristine • Vincasar PFS
Ziprasidone • Geodon