Gina Clowes: Hi Dr. Green. Thank you for talking with us

Dr. Todd Green

today about a potential new treatment for food allergy:

GC: I'm happy to. First, I'd like set this up with a little overview of immunotherapy in laymoms terms.

Many of the treatments for allergy today are forms of immunotherapy- where physicians give tiny amounts of the allergen in increasing doses to help the body become desensitized (less reactive) and eventually tolerant of the allergen.   

Subcutaneous immunotherapy (SCIT), commonly known as "allergy shots" is the best known form of immunotherapy. We don't use this for foods but for seasonal, venom and environmental allergies.   

Oral Immunotherapy (OIT) is giving tiny amounts of the allergen (the actual food) over time. Sometimes this is combined with a drug (like Xolair) that dampens down the allergic response to hopefully make the process safer.   

Epicutaneous immunotherapy (EPIT) is immunotherapy administered through the skin. In this case, through a skin patch that has small amounts of the allergen (peanut- in the study we're discussing today).     

GC: So, how does desensitizing through the skin work differently than orally or sublingually ?

TG: First, it seems to be safer. One reason is that with this exposure the allergen doesn't go into the blood stream through the intact skin. We haven't been able to measure peanut protein in the blood after this type of exposure.  

GC: How does the patch work?

TG: There are specialized cells in the skin that take up the peanut and travel to lymph nodes, where they interact with other cells of the immune system to shift the body's response away from an allergic one.

The basic idea is that we all get exposed to the same "foreign" materials, whether these be foods or pollens or cat dander. The immune system has different ways to respond to these exposures, and one type of response is an allergic one. With immunotherapy, we are using low dose exposures to "redirect" the body's immune reaction from an allergic to a nonallergic one.

This is the idea behind all forms of immunotherapy. The patch attempts to do the same thing that injection or oral forms of immunotherapy do, and our hope is that it does so in a safer but still effective fashion.

GC: So, the allergen in the patch acts on cells that regulate allergic reactions without entering the bloodstream. Because it is not absorbed by the bloodstream, the risk of an allergic reaction is reduced.  

TG: It's for safety and efficacy. Both.

GC: I see. They've already completed studies on safety though. What did they find? What kind of reactions did they see, if any?

TG: It seems to be very safe. It is common for kids to get irritation, redness or itching at the site. These are typically mild though.

GC: Do the participants experience anaphylactic reactions?

TG: We're not seeing these types of severe reactions with this like we do occasionally see with oral immunotherapy.

GC: Have you seen any eosinophilic disease, EoE etc?

TG: We have not seen that, though the studies to date have been of fairly short duration. We're hopeful that we will not see EoE, however, since this method of exposure involves skin exposure to peanut, not direct exposure to the GI tract.

GC: Can kids with eczema participate?

TG: Yes, but they need to have enough clear skin so we can apply the patch. They also have to go off of antihistamines for the initial skin testing and food challenge. They can use medications once the study is underway.  

GC: What symptoms do participants experience? Does this treatment exacerbate asthma or eczema symptoms?

TG: We have not seen an increase in asthma or eczema in the early studies.

The main symptoms are limited to the skin: swelling, redness and itching at the site.

We have the families record the intensity of these symptoms on a scale of 0 to 3 every day, with 3 being the most intense. At this point the large majority of symptoms have been graded 0 or 1.

GC: Could this treatment make a child with multiple food allergies more susceptible to other food allergy reactions?

TG: Not that we know of, and we don't think that is likely, but that is not being tested specifically.

GC: Where does the patch go on the body?

TG: In younger children, it goes on their backs. Those who are 12 years of age or older will put the patch on their inner arms.

GC: One patch per day?

TG: Yes, they put one patch on each day. They can put it on at any time of day. They will rotate through six different sites though.

So for the younger kids, they'll go on the back, in two rows, in between the scapula. There are three sites on the first row and three on the second row.

For the older kids and adults, they have one row of three on each arm.

They wear a patch on site #1 for 24 hours. The next day, they switch to site #2 and so on.

When they have irritation after removing a patch, they can use hydrocortisone cream there. In five days, that site should be ready for the next treatment.

GC: We've heard reports of increased reactions during oral immunotherapy when kids are sick. Does this happen with the patch?

TG: We haven't seen that. But we are still learning about this potential therapy.

GC: Are you skin and blood testing throughout the process?

TG: Yes, there are regular visits throughout the study and we will be tracking skin and blood test results.

GC: I'm surprised to hear you are skin testing. I thought that the skin would often hang on to reactivity so it would be hard to measure any real progress.

TG: You're right that is often the case. We are following the skin tests in order to help us learn about how this type of exposure affects the immune system. Skin and blood tests both offer ways to follow the body's immune response. We won't challenge these participants again until they have worn the patch for 12 months, and that will be the ultimate test of the clinical effect, but the skin and blood tests along the way will also help us learn.

GC: Can you get the patches wet?

TG: Yes. Participants can take it off when they shower or bathe, or they can get it wet.

We've had questions about swimming, too. Participants can swim with it or can take it off when swimming. If they've had it on most of the day, and it comes off in the water, they don't have to replace it until their usual time of replacement. We want them to wear only one patch in 24 hours.

GC: What are the ingredients in the patch? Is it only peanut?

TG: There is mannitol, ethanol and sodium chloride along with peanut.

GC: Is there latex in the patch?

TG: No.

GC : What is in the placebo version?

TG: Just the other ingredients I mentioned. And it looks the same.

GC: Does the placebo patch work?

TG: We won't know really until the end of the study. But we do see a placebo effect in most studies. We don't suspect that the placebo will work as well, however, or in as many people-but that is why we do the study.

GC: That fascinates me. I can't wait to hear more on that one.    So this study is for 12 months and they use one patch per day. Any special procedures for this?

TG: They start out leaving the patch on for 3 hours per day the first week. The second week they leave it on for 6 hours a day. Then 12 hours for the third week and 24 hours per day for the fourth week and beyond.

GC: Is anyone completely tolerant to peanut after using the patch?

TG: That would be great. The highest single dose during the initial challenge is 300 mg (about one peanut). At the end of the challenge, as long as the subject is not having a reaction, the highest single dose is 2000 mg (about 4400 total mg for the whole challenge). These participants will still be wearing the patch, however, at the end of the challenge.  

With immunotherapy we distinguish between the concepts of desensitization, which lasts only as long as the exposure (in this case, the patch) continues, and tolerance, which is a long-lasting effect that does not depend on continued exposure. This study will determine whether participants are desensitized. Future studies may investigate tolerance.

Also, this is a one-year study, but those who participate may be eligible to continue in a 2-year follow-up study. Those who received placebo during the first year will have the opportunity to cross over into the treatment group.

GC: Is the goal to have this as a stand-alone treatment or for this to be used in conjunction with oral immunotherapy?

TG: It's being looked at as a stand-alone but in theory this could be looked at in combination with other therapies as well

GC: Do you have to have a certain skin or blood test result to be eligible?

TG: Yes. You have to have a skin test result of at least 8 mm wheal or a blood test at greater than .7 kU/l.

GC: Do we know anything about how kids or adults handle this type of treatment emotionally? Is it less anxiety provoking because we're not eating it, or the same or more, because you "know" that peanut is on your skin 24 hours a day?

TG: No. We don't know at this point. That will be interesting to study. We do know that fortunately these exposures seem to be very well tolerated.

GC: The patches are different dosages. Why?

Do the higher dosages mean increased tolerance-that you can eat more peanut?

TG: We're trying to figure out the optimal doses. That's one of the things that we'd like to know.

GC: Would you share a little of how the study unfolds?

TG: There are two main goals for the study. One is to get our participants to eat 1000 mg of peanuts (about 3 peanuts).

To get into the study, we're challenging them with 444 mg. total. It's a six step challenge. We start very slow. The final step is 300 mg.

After 12 months of wearing the patch, they will be challenged, again starting at a very low dose (1 mg) with up to 1000 mg and then 2000 mg of peanut. We're hoping that we can get them all to 1000 mg of peanut protein or at least a 10 fold increase from their baseline---from what they tolerated at the beginning.

The food challenges are obviously one of the riskiest and most anxiety-provoking parts of this study. In order to qualify for the study, participants need to objectively react to a fairly small amount of peanut protein. There is the potential for a bad reaction. That said, the majority of reactions in the study thus far have been fairly mild and easily treated.

We are very aware of the risks these challenges pose, and are extremely cautious and careful. These are done in the hospital, under very close monitoring by a physician and nurses, and with medications immediately available.   

We are hopeful that this study may lead us to a new treatment for food allergy beyond avoidance, and we are grateful to those who are willing to participate.

GC: That sounds promising. So are there other food allergies can be treated with a patch?

TG: Yes, there was at least one study using a milk patch. They only watched them for 3 months but the group did trend toward being able to tolerate more milk. They went from drinking 2 ml of milk to about 24 ml of milk.

GC: Why did you become interested in this form of immunotherapy?

TG: The main thing is that it seems to be a very safe therapy.

Most kids who are allergic react the first time they eat the food. So we think that the sensitization may occur though the skin initially. So if you can become allergic through the skin, we're hopeful that we can desensitize you through the skin.

GC: That sounds wonderful! Thank you talking with me today about this promising new treatment! I hope you enroll many new patients in the days and weeks to come.

For more information or to enroll in this study at Children's Hospital of Pittsburgh please call 1-877-296-9026.

Todd Green, MD, is Assistant Professor of Pediatrics at Children's Hospital of Pittsburgh of UPMC. He completed his fellowship in allergy/immunology at Duke University, under Dr. Wesley Burks, where he worked on the early oral immunotherapy trials for milk, egg, and peanut; he continues to have a clinical and research interest in treating patients with food allergies.