Friday, March 1, 2013

Milk Allergy Cure: Glass Half Empty, or Half Full?

So there's been a lot of press coverage coming out of the AAAAI meeting about how OIT is not ready for prime time. Of course, it's nowhere near the volume of THERE'S A CURE FOR PEANUT ALLERGY headlines that hit when they started the therapy several years back, and it will probably take another 10 years before acquaintances stop coming up to me with printout off the internet that seem to imply I'm just not trying hard enough to cure my kid's allergies...but I digress.

One of the best summaries I saw was from Science News (love those guys!). The article led with the bad news:
Researchers at Johns Hopkins University report that many children have seen their allergy return several years after completing a similar regimen of what allergists call oral immunotherapy. “I think they’re not as protected as we were led to believe,” says Robert Wood, an allergist at Johns Hopkins who reported follow-up data on 32 patients.
However, the next paragraph gives the stats for all milk OIT trials:
Of the 280 patients treated for at least seven months, 160 were able to consume 7,200 milligrams of milk protein, the equivalent of about one-fourth of a liter of milk, without a reaction by the end of the study. “They are eating freely all dairy foods,” Levy said. Another 66 patients who finished the treatment can handle smaller amounts of milk regularly, and 15 are still working through gradual escalations.
I think it's interesting that the coverage of these trials has mostly been negative. Perhaps it's backlash from the (unwarranted?) hype that went before. Perhaps it's because the researchers don't want this therapy to be tried in physician offices without appropriate rescue meds/equipment on hand. 

I looked at it and said "Geez! 60% odds of outgrowing! Sign us up!" 

But here's the kicker:
In the other analysis, which included patients from two previous smaller studies, Wood reported that only eight of 32 children who received treatment three to five years earlier at Johns Hopkins were still free of symptoms when ingesting milk. Five can’t touch it, and the rest have occasional to frequent reactions to milk, Wood said. 
So...over time, a treatment that looks like it's successful can suddenly unravel, sometimes with a big reaction. Some subset of kids can end up more sensitive, with a lower threshold than when they started. Plus, during the treatment, they were far more likely to have serious reactions (almost 1 in 10).

SLIT (under the tongue therapy with very low doses of protein) also had some success, although more modest:
Dr. Thompson pointed out that [a parent's choice about which therapy to pursue] depends on the goal of therapy. "If your end point is to have someone consume milk and peanuts regularly, then you might try the oral, but if you're just trying to keep them from having an unexpected severe allergic reaction, then you should probably just go with sublingual. This is often good enough for most parents. They don't care if the kid can eat peanuts, they just want to make sure that if he eats something by mistake or sits at the nonpeanut-free table, he's going to be okay," he explained.

So...you get to Choose Your Own Adventure with this one:

If you're a glass-half-empty person, you might conclude that all these therapies have risks and that it's not worth it to go through something, let down your guard, and then have your child suffer a bad reaction, perhaps followed by a lower threshold.

If you're a glass-half-full person, you might conclude that the 6-in-10 odds in the first study, and the 1-in-4 odds in the second one, are still a pretty good bet to not have to live with milk allergy. And, if it goes bad, perhaps there will be a new therapy like Xolair or FAHF-2 that can make things better.

If you're a researcher, you probably look at all this and think: whoa! Are food allergies like cancer, where each person's fingerprint is slightly different? Are there other factors that are working in conjunction with tolerance, such as pollen load, hormones, time of year (which might affect Vit D uptake), or environmental pollutants? Did some kids outgrow because of who they were genetically? Or did some kids remain tolerant because of what they did environmentally? Did the therapy re-educate the immune system and then it regressed for some reason? Or was the immune system not changed at all and the kids were desensitized, not truly tolerant?

Tucked away in the tweets from the meeting was this little gem:
Clinical phase I trials of FAHF2 showed that is probably safe. Phase II trial is underway but requires 30 pills/day!
"Probably" safe? Just a reminder that all these little adventures have no guarantees. So far, we're very happy with the FAHF-2 road-less-traveled, but only time will tell.


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