Sure I can explain what it's all about
and let's start with a brief history lesson.
The first medication of this type of biologic was known as TYSABRI (natalizumab) which blocked both MADCAM1 and MADCAM2. It was discovered that by blocking MADCAM2, it had a rare side effect of PML that affect the brain and a black-box label was added to the medication.
Subsequently, a new Entyvio (vedolizumab) was specifically developed to only block MADCAM1 and thus not have any chance of the PML side effect. MADCAM1 was shown to be gut-specific, and only affects the gut as intended. There has been no instances of PML with entyvio either during clinical trials and while the medication has been available on the market. As entyvio is within the same class of medications as Tysabri (both MADCAM-inhibitors), the FDA mandates that the PML black box warning appears on both medications labels.
So entyvio patients aren't typically tested for the JCV virus, there's no incidences of PML with it, and in theory there should be zero chance of ever getting a PML on entyvio. As entyvio was developed to avoid the possibility of it. Takeda Pharmaceuticals developed both medications, and entyvio is an improved, safer medication.
Edit: Added Details
Generally you are not going to see TYSABRI prescribed at all for UC. Rather, it's pretty much limited to MS patients, who as a generalization have a broader acceptance of risk due to the severe debilitating nature of MS.
Moderator Ulcerative Colitis
John, UC Proctosigmoiditis in Remission
Rx: Remicade @5mgs/kg/6wks; daily 75mgs 6MP, and rowasaYou might have UC... if you take the dog for a walk and you both end up pooping within the bushes.
Post Edited (iPoop) : 4/17/2019 12:16:17 PM (GMT-6)