PML, Progressive Multifocal Leukoencephalopathy, a rare and sometimes fatal brain infection who’s symptoms are similar to Multiple Sclerosis, has always been synonymous with Tysabri (Natalizumab) but last Tuesday a case of PML was reported by a patient taking Novartis’ Gienya (Fingolimod). Gilenya is an oral DMD (Disease Modifying Drug) that was approved by the FDA in 2010 with the most common side effects being no more severe than headache, influenza, diarrhea, back pain, abnormal liver tests, and cough but now will we see PML be added to the list?
Tysabri, the once a month, intravenous (IV) DMD, that is most commonly known to be the “DMD that causes PML”, was approved in 2004 and temporarily taken off the market in 2005 because of 3 cases of PML that had come up. 1 year is much quicker than the 3 years it took to see PML in Gilenya so most likely PML will remain to be much more rare in Gilenya than it is in Tysabri but a risk is a risk and if Gilenya really does turn out to be the cause of this case of PML what will that mean for the FDA’s approval of Gilenya? Will this warrant a warning label change? Perhaps the risk associated with PML and Gilenya just takes longer to present than it does in Tysabri? That makes me wonder, will we be seeing more cases of Gilenya related PML start popping up?
“By the time there was a similar level of patient experience with
Tysabri there had been 298 cases reported. Thus, even if the risk proves
to be real it is likely to be of a very different order of magnitude,” -Deutsche bank analyst Tim Race