|Rye grass is the major cause of hayfever in|
southeastern Australia. Image WA DPRD
Trials conducted by Monash University scientists have shown that a tablet dissolved under the tongue – sublingually – may help safeguard seasonal allergic rhinitis (spring hayfever) sufferers against the deadly effects of thunderstorm asthma.
The allergen immunotherapy Oralair was tested over three years by researchers in the Department of Allergy, Immunology and Respiratory Medicine at the Central Clinical School/Alfred Health led by Professor Robyn O’Hehir.
Results showed that none of the patients with seasonal hayfever taking Oralair displayed symptoms of allergic rhinitis or asthma during the catastrophic thunderstorm asthma event in 2016, which affected thousands and claimed 10 lives.
The study, published in the leading international respiratory journal American Journal of Respiratory and Critical Care Medicine, has attracted considerable national media attention, appearing on dozens of TV stations around Australia, Channel TEN’S The Project, radio stations including 3AW and the ABC, as well as newspapers including The Herald Sun.
The treatment desensitises against rye grass pollen allergy, the major cause of hayfever in southeastern Australia, which can trigger sudden and severe asthma. Seventeen ryegrass pollen allergic patients took Oralair for the four months to spring from 2014 to 2016. Of the other 17 ryegrass pollen allergic patients in the study who chose to take only symptomatic medicines (anti-allergy nose sprays and antihistamines) rather than the treatment, seven or 41 per cent suffered an asthma attack that forced them to go to the hospital emergency department or their GP and to need steroid treatment.
Professor O’Hehir said the researchers had been thrilled to find that the treatment, while designed to control rhinitis, was able to offer additional protection against thunderstorm asthma.
“Oralair retrains the immune system to behave like that of a non-allergic individual by inducing the production of regulatory T cells, and also a different isotype of antibodies, ryegrass pollen-specific IgG4 that block IgE-facilitated allergen presentation and therefore protect against allergy symptoms,” she said.
“I was confident that a shorter pre-seasonal course would be sufficient for efficacy, better for patient adherence and cost and avoid administering extra pollen during spring when environmental pollen exposures can be extreme.”
The study suggested Oralair could be used pre-seasonally for three years by hayfever sufferers. It is available by prescription but is not currently listed on the Pharmaceutical Benefits Scheme (PBS); the cost is $350 for four months’ supply. Hayfever treatment has typically been pharmacotherapy such as anti-histamines and nasal sprays.
An estimated 4.6 million Australians suffer from hayfever putting all who have it in south-eastern Australia at risk of thunderstorm asthma. Professor O’Hehir said “every patient with spring hayfever should be aware of the risk of thunderstorm asthma particularly in November and ensure they have access to an asthma reliever if needed.”
She said she hoped to conduct a larger trial with 400 patients with a view to inclusion of grass pollen sublingual immunotherapy in the Global Initiative for Asthma (GINA) Guidelines to prevent spring hayfever and the associated risk of spring asthma.
This trial was supported by the Num Pon Soon Charitable Trust.
The printed publication of the study currently online will appear open access in the American Journal of Respiratory and Critical Care Medicine on July 1.
The CCS blog last week reported on a large multidisciplinary study in Lancet Planetary Health that investigated the 2016 epidemic thunderstorm asthma event – the biggest, most catastrophic event of its kind globally. The study involved 11 Monash University-affiliated co-authors.