Disproportionality signal of progressive multifocal leukoencephalopathy: monoclonal antibodies versus other immunosuppressants

In 2010, our analysis of spontaneous and published reports of Progressive Multifocal Leukoencephalopathy (PML) coming from different sources (FDA Adverse Event Reporting System–AERS, WHO VigiBase and MEDLINE) suggested a possible strong relationship between PML and Monoclonal Antibodies (MAbs), especially when used in autoimmune diseases. Recently, Schmedt and colleagues, by using the public version of FDA AERS, have performed the first disproportionality analysis for the possible association between PML and immunosuppressive drugs, and found disproportionality signals for several immunosuppressants, especially MAbs (e.g. natalizumab, efalizumab and rituximab). This study prompted us to refine our analysis by applying a similar disproportionality method, in order to confirm or reject our previous speculation. Therefore, we performed a step-by-step disproportionality analysis for PML in the FDA AERS database by checking disproportionality for: (i) immunosuppressants vs. other drugs; (ii) among immunosuppressants, MAbs vs. Non-MAbs and (iii) each MAb, separately.