The first reported case of a patient with PML treated with OCR and without prior DMT was a 78-year-old male who had received OCR for 2 years Lymphocyte test revealed grade 2 lymphopenia (780/μL), with a CD4+ count of 294/μL (normal range: 325–1,251/μL) and CD8+ count of 85/μL (90–775/μL). Here, CD4 is linked to progressive multifocal leukoencephalopathy.