A short history lesson on the meds Natalizumab and vedolizumab/entyvio. The first medicine of this class, Natalizumab, had low odds of causing PML of 7 in 10,000 (or 0.07 percent). Inversely, 99.92 percent of patients did NOT get PML. Natalizumab blocks both MADCAM 1 and 2 within our bodies. Further research found that blocking MADCAM 2 was the reason for the low PML odds as MADCAM2 affects the brain. MADCAM1 is gut specific immune suppression.
Entyvio/vedolizumab was specifically designed to not cause PML as it blocks only MADCAM 1. It's no surprise there have been zero PML cases with entyvio, as it was engineered to not cause PML. The clinical trials and reporting since release to market back this up, it hasn't happened. As these two meds vedolizumab and Natalizumab are of the same class of MADCAM blocking meds, the FDA rules state they both must have the black box warning about PML.
Natalizumab is still in use for MS, but not used at all for UC.
This has given me great comfort. I was sitting at the infusion centre waiting my 2hrs after my infusion and decided to start googling. I almost passed out when I came across the article on PML. By the time I’d driven out to where I live, stopping at my Drs surgery I was in a full blown panic attack, certain I was suffering PML because I missed the arm rest trying to get out of the car in a panic and fell on my face. My Dr convinced I’d suffered an allergic reaction because he hadn’t seen me without a mask since the start of covid and I had moon face from the prednisone so he insisted on an antihistamine injection. I tried to tell him that’s just how my face looks now but grateful he wasn’t taking any chances. Thankfully the nurse helped me control my breathing down enough so it became pretty obvious it was anxiety by the time the ambulance came. I have been contemplating stopping entyvio because I didn’t want to live in fear of this. Honestly it made me question surgery all over again so I Thankyou for your reply