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A treatment for food allergy: Are we there yet?
An update on the latest research into immunotherapy for food allergies.
As the rates of food allergy continue to increase, the search for a cure or effective long-term treatment continues around the globe. Speakers at the ASCIA conference in Canberra in September indicated that we are getting closer but there are still questions to be answered.
Various forms of immunotherapy are being trialled, which aim to desensitise the immune system to the food allergen concerned. This is done by introducing tiny, then ever-increasing, amounts of the allergen over time, then maintaining a particular dose for a longer period.
There are many approaches being tested, including different food allergens, the form and route it is introduced in, use of adjuvants (e.g., probiotics or medicines), dosing rates and the time periods for each phase. While the overall picture is certainly not clear at this stage, knowledge is increasing in respect to the potential for a viable treatment for food allergy.
One of the issues is being able to define the intended outcome for a treatment and having a way to measure whether this has been achieved. There are three potential outcomes from immunotherapy: desensitisation, sustained unresponsiveness, and (described as the Holy Grail) tolerance.
Desensitisation is defined as a reduction in sensitivity to the food concerned, meaning less likelihood of reacting to a small amount. This is seen as a temporary state that exists while you maintain the treatment. It’s intended to offer some protection from a severe reaction to accidental exposure to the food. It doesn’t mean you can simply eat the food and be safe, but may be sufficient to reduce anxiety and improve quality of life.
Sustained unresponsiveness means no reaction to the food in a challenge after stopping taking the daily maintenance dose. Critical issues for researchers include determining how long the state of unresponsiveness will last once the treatment finishes – and whether it requires continuing to eat the food regularly to maintain this. Some trials have found that after a period of sustained unresponsiveness, a number of participants stopped eating the food because reactions reoccurred.
Tolerance means being able to eat any amount at any time as with any other food. It’s not clear that any immunotherapy trial has been able to achieve this to date. However, some evidence is emerging of potential markers of tolerance being changes within the immune system itself.
What is also emerging in research is the need to develop treatment that can be safely managed at home or in a community setting. Oral immunotherapy seems to be effective in achieving a level of desensitisation, but there are safety issues including reactions experienced during treatment. This means it has to be conducted in clinic settings under supervision of health professionals. As a treatment for the many thousands of those with food allergy, this would be unrealistic to provide.
In our favour is the passion and commitment of the researchers, determined to find a treatment, and the many individuals, including children and their families, willing to participate in clinical trials for the benefit of others, not just themselves. We will get there!
Allergy New Zealand allergy advisor Penny Jorgensen