One of my favorite stories is the tale of a GMO virus deployed to treat Hemophilia B:

Gene therapy for Hemophilia B ... Hemophilia B is a disease in males caused by point mutations/deletions/etc in the clotting Factor IX gene. If you dont make Factor IX, you wont clot properly, and will have all of the health issues we associate with hemophilia. ... The scientists in this paper took six Hemophilia B patients, and treated them with an Adeno-Associated Virus-8 (two at low, medium, and high doses of virus) that contained a functional copy of the Factor IX gene. Four of them of them bumped up their Factor IX production enough to go off pharmaceutical Factor IX treatment all together (even with one of the dudes being a marathon runner!), and the two others went from needing treatments several times a week, to only needing a treatment once every couple weeks or so.

Okay, I wrote that post late 2011.

They published an update late last year:

When you are treating a genetic disease with gene therapy, the point is to treat them once and be done with it. Broken gene-->Fix the gene--> DONE! And its reeeeeally important that everything works well the first try, because second/third/fourth tries with GMO viruses complicate things.

See, your body doesnt 'know' the GMO viruses are there to help. So your immune system sees the GMO virus and generates antibodies to kill those viruses the next time they see it. The more times you have to administer a GMO virus, the more antibodies a person will make, the less likely second/third/fourth doses will do a damn thing.

So what happened in these patients up to four years after they were treated? How good was that one dose?

They followed the six from the previous study, plus another four (who got the 'high' dose of virus), who all got one dose of Adenovirus-Associated Virus-8, genetically modified to deliver a functional copy of Factor IX.

The treatment was safe-- There were no terrible side effects. Some had annoyed livers right at treatment, but prednisone fixed that. No long-term problems.

And boy, did this GMO virus help long-term!

The patients were nowhere near 'normal' levels of Factor IX, BUT, the viruses got enough functional Factor IX floating around to:

The annual amount of factor IX concentrate that was administered to all 10 patients dropped from a median of 2613 IU per kilogram (interquartile range, 1671 to 4513) in the year before vector infusion to 206 IU per kilogram (interquartile range, 79 to 948) in the year after vector infusion (P=0.002), a relative reduction of approximately 92%. In the high-dose group, the amount of factor IX concentrate that was used dropped from a median of 2613 IU per kilogram (interquartile range, 1627 to 3487) to 92 IU per kilogram (interquartile range, 38 to 395), a relative reduction of 96% (P=0.03). Despite this decline in factor use, the annual number of bleeding episodes for the entire cohort of 10 patients decreased from a median of 15.5 bleeding episodes (interquartile range, 10.3 to 19.3) 1 year before vector infusion to 1.5 episodes (interquartile range, 1.0 to 4.0) in the year after vector infusion, a relative reduction of 90% (P=0.009). When only patients in the high-dose group were considered, the annual number of bleeding episodes decreased from a median of 16.5 episodes (interquartile range, 12.5 to 27.0) to 1.0 episode (interquartile range, 0.8 to 2.5), a relative reduction of 94% (P=0.03). ... The overall reduction in the amount of factor IX concentrate that was administered over the duration of the study was more than 3 million units, resulting in a financial savings of more than $2.5 million based on 2014 prices.

The amount of therapeutic Factor IX these patients needed (on average) dropped from 2613 IU/kg to 206. The people who got the 'high' dose of virus dropped that down to 92 IU/kg. They went from 15-16 'bleeding episodes' a year, to one.

ONE.

And not only were these individuals lives improved, not being shackled to a hospital for IV treatments of Factor IX, not having regular 'bleeding episodes', their ability to live without these treatments saved $2.5 million.

'GREAT JOB!' to the scientists and physicians involved with this, and I hope they get this therapy to more folks ASAP!