<unk>  appears to interact with other immune-modulating drugs to increase the risk of progressive multifocal leukoencephalopathy (PML), an often-fatal opportunistic infection caused by the JC virus. In 2005, two people taking<unk>  in combination with interferon beta-1a developed PML. One died, and the other recovered with disabling sequelae. A third fatal case initially attributed to an astrocytoma was reported in a patient being treated for Crohn's disease. Though the patient was being treated with<unk>  in combination with azathioprine, corticosteroids and infliximab, indications of PML infection appeared only after<unk>  monotherapy was re-introduced. No deaths from progressive multifocal leukoencephalopathy have been linked to<unk>  when it was not combined with other immune-modulating drugs and other rates of opportunistic infections are not increased in patients taking<unk>  possibly due to the drug's mechanism of action. Other than a prior history of PML, there is no known method to identify patients at risk of developing PML.<unk> 's label indicates that it is contraindicated for immunosuppressed individuals or those with a history of PML. Due to the uncertain risk of PML,<unk>  is only available through a restricted distribution program. By 21 January 2010 the United States Food and Drug Administration reported a total of 31 confirmed cases of PML associated with<unk> . Though the small number of cases precludes conclusion on the ability of<unk>  alone to induce PML, its black box warning states that the drug has only been linked to PML when combined with other immune-modulating drugs and<unk>  is contraindicated for use with other immunomodulators. Corticosteroids may produce immunosuppression, and the Tysabri prescribing information recommends that people taking corticosteroids for the treatment of Crohn's disease have their doses reduced before starting<unk>  treatment. The risk of developing PML was later estimated to be 1 in 1,000 (0.1%) over 18 months though the longer term risks of PML are unknown.
Natalizumab
Brolucizumab
Satralizumab
Ravulizumab
Mogamulizumab
Inebilizumab
Emicizumab
Ixekizumab