Oral immunotherapy can desensitise for peanut allergies, but at what cost?
An oral immunotherapy product for peanut allergy gained FDA approval in February, but the peak body for allergists and immunologists in Australia is advising against the use of this controversial treatment.
Oral immunotherapy involves a patient eating a gradually increasing amount of peanut protein over several months, with the aim of being able to safely consume a standard serving of peanuts by the end of the treatment.
Over the past decade, some paediatricians in the US, Europe and Japan have been offering oral immunotherapy in the form of small, increasing doses of peanut flour.
The FDA has now approved an oral immunotherapy product called Palforzia, which provides a standardised dose of peanut protein in the form of powder inside a capsule that then is sprinkled over food.
This product, manufactured by Aimmune Therapeutics, costs patients around US$11,000 a year, but it remains unclear whether it has any benefits over simply weighing out inexpensive peanut flour.
While oral immunotherapy is taking off overseas, it is still undergoing clinical trials in Australia.
And Australian allergists remain extremely cautious about its use.
The Australasian Society of Clinical Immunology and Allergy (ASCIA) updated its website earlier this month to communicate its position that oral immunotherapy is still not ready for prime time.
The best advice for patients with food allergies was still complete avoidance of confirmed food allergens, ASCIA said.
Patients who were participating in clinical trials for oral immunotherapy should be advised of the increased likelihood of allergic reactions, including anaphylaxis, and be prepared for these events, ASCIA said.
Metaanalyses published in The Lancet and Scientific Reports showed that people receiving oral immunotherapy for peanut allergies had more frequent allergic reactions, including anaphylaxis, and self-injected with epinephrine more often than patients who did not receive oral immunotherapy.
ASCIA’s message for doctors was: “Watch this space”, said Dr Lara Ford, the chair of the ASCIA paediatric committee and a paediatric allergist and immunologist at The Children’s Hospital at Westmead in sydney. “This is a rapidly evolving area,” she said.
Palforzia was not yet approved by the TGA, so there was actually no material change in the options available to patients in Australia at present, she said.
Australian allergists now largely accepted that oral immunotherapy could successfully desensitise people with food allergies. But the question was whether the benefit was worth the risks and whether those risks could be mitigated by the use of co-treatments, such as probiotics or dietary fibre supplements, she said.
Those questions were the focus of clinical trials being undertaken in Australia.
“The main reason that oral immunotherapy has not hit mainstream clinical practice is because there are lot of problems with it,” Dr Ford said.
It was a resource-intensive treatment because patients needed to be under clinical supervision every time the allergen dose was increased in case they experienced a severe allergic reaction, she said.
Allergic reactions to food were not at all predictable; patients who usually had mild-to-moderate allergic reactions could have severe reactions and visa versa.
A large proportion of patients had allergic reactions while undergoing oral immunotherapy that they wouldn’t otherwise have had if they followed the current advice of strict avoidance of food allergens, Dr Ford said.
And there was very little data on how long lasting the oral immunotherapy treatment was, or what patients needed to do to maintain desensitisation. It could be that patients needed to keep taking the dose of peanut protein daily for the rest of their lives or lose the protective effect of the treatment altogether, she said.
Oral immunotherapy placed many restrictions on patients’ lifestyles. Patients couldn’t exercise immediately after taking the dose of peanut protein or take a hot shower because this was known to increase the risk of severe allergic reactions.
This made oral immunotherapy “quite onerous” and many patients “fall off the wagon and stop doing it daily”.
