Sunday, June 1, 2008

New grass pollen immunotherapy shots

I was asked to comment on a news release dated today by Allergy Therapeutics ( concerning their trials with a new type of immunotherapy (IT) for grass pollen. First, a public disclaimer, I had no part in the study nor do I own any Allergy Therapeutics stock. Second, I am glad to read that the study was completed and that the full results will be publicly presented. The release highlights statistically significant results that also sound promising. That the results will be presented by Dr. Frew, a renowned researcher, is good, too. Recognize that this is a news release and that of the 3 pages, 4 brief paragraphs actually discuss the study. More details are essential to fully analyze the study before embracing the results. I am sure Dr. Frew will discuss details such as how long was the study, what was the length of followup, and what is the duration of the significant effect at the followup time points? This is certainly a step in the right direction. Clinically, allergy patients may have to deal with multiple allergens, such as tree pollen (spring), grass (summer), weeds (fall), molds, dust mites, and animal danders. If they have clinically significant allergies from more than grass, this therapy would not help reduce the patient's symptoms completely. Theoretically, the same type of therapy for each of these allergens would be necessary.

Here are some questions I was asked.
1) So is this a significant advance over existing grass pollen therapies? Short answer: may be. Long answer: it's good that is better than placebo, otherwise we wouldn't be having this discussion. There are no comparative trials of classic IT to 4-shots that I am aware of. Here's a meta-analysis for classic IT. The size of the effect varies in the literature and so which study is cited. The meta-analysis does not even give a number of a range. In the first year alone, I would say that classic IT's effect is superior, about 40-50% reduction. So based on the data they have provided, it's not superior so far to me. On the other hand, I think it is a gross overstatement to say that everyone feels 100% better on IT than without it. It does not work for everyone and we don't know why.
2) Why is this an advance? Because there should be higher compliance, lower costs, less time and discomfort from getting 4 shots compared traditional IT which involves on average 52 shots at 1x/week for the first year, then 26 shots/year for years 2-4 for most people. With time, more research, more money, and good luck, the technology will advance to improve the effect. The critical factor will be money, which makes the wheel go round. They aren't the first or last company chasing the holy grail for allergy IT. Note the size effect is small, but the convenience is very high, hence for financial and patient preference reasons, it should be successful. People will try anything repeatedly under their own direction rather than get the much more effective traditional IT. "Theoretically", if this is more effective, this could revolutionize IT around the world. There is the very significant hurdle for any company, which could be prohibitive, of developing IT that will take care of ALL of the allergies each patient has.
3) Are there any other forms of IT available? Oral IT is approved already in Europe, but not the U.S.
4) How does regular IT work? Normally, people have a high immunologic tolerance, so when they breathe in pollen etc., their immune system ignores it. If you have allergies, your immune tolerance is lower than average, so you do not tolerate contact with pollen, your immune system reacts, produces chemicals and activates immune cells to attack this problem. An IT extract is a sterile, dilute solution of whatever they're allergic to, dust, mold, pollen, animal dander. The extract is given in small and increasing amounts to build-up to a maximum dose. This dose is then given routinely every 1-2 weeks for 3-5 years total. It takes that long for the immune system to improve to its personal best, hopefully normal levels, and more importantly stay there for the long term, even after IT shots are stopped.
5) Any final thoughts? I think their results are worth noting, so long as due diligence is given to the fact that this is compared to placebo, not a proven effective treatment, and that are significant hurdles for many patients. Long term data of course on safety and duration of efficacy is completely lacking and this should be noted too. Even if approved, given its limitations, it could be 3-4 years minimum until it is available for routine use.

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