Q&A: Sublingual immunotherapy safe, effective for children with peanut allergy
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Sublingual immunotherapy for peanut allergy was safe and effective among children aged 2 to 12 years, making it a promising alternative to oral immunotherapy, according to a study published in The Journal of Allergy and Clinical Immunology.
During this open-label, prospective study, the mean successfully completed dose increased from 48 mg to 2723 mg of peanut protein by 48 months. Also, 70% of the participants achieved clinically significant desensitization, and 36% achieved full desensitization.
The study found a 0.5% median rate of reaction per dose as well, with transient oropharyngeal itching among the most common symptoms, and no dosing symptoms that required epinephrine.
Healio spoke with Edwin H. Kim, MD, MS, associate professor of pediatrics and division chief of UNC Pediatric Allergy & Immunology at University of North Carolina School of Medicine, to find out more.
Healio: What prompted this study?
Kim: OIT has been the most studied treatment for peanut allergy. The data is clear that it can be effective at desensitizing allergic patients. However, it comes with a significant risk for allergic reactions and, practically speaking, the frequent number of doctor visits, the preparation of the product for eating and restrictions on activities around dosing make it difficult to do.
We think that sublingual immunotherapy (SLIT) can be an easier treatment for peanut allergy, and prior studies have shown that it is safer than OIT to do. With this study, we wanted to first show that peanut SLIT can be very effective at desensitizing. Second, we wanted to show with more detail than previously seen what happens when you stop treatment.
Healio: How is SLIT administered?
Kim: Peanut SLIT is provided to patients as a liquid extract in a small plastic bottle with a pump. For dosing, the nurse or parent administers the designated number of pumps of the SLIT liquid under the tongue of the patient. The patient holds the liquid there for 2 minutes and then swallows the liquid. For young kids, keeping the liquid there can be hard, so we try to get them to hold their tongue up and sing songs or otherwise distract themselves.
For reference, the maximum dose of SLIT we give is 4 mg of peanut compared with the Aimmune Palforzia peanut flour, which is 300 mg, and the recent IMPACT study, which used 2,000 mg. I bring this up because some folks have wondered if this is just another version of swallowed OIT. But most people would agree that it is hard to believe that 4 mg swallowed is enough to have any effect, let alone the results that we have seen.
After the dose, we typically watch the patient for 30 minutes to make sure there are not side effects, and then the patient goes on their way. The standard Palforzia OIT protocol has 10 or 11 office visits over a 6-month period. Our newest SLIT protocol has five monthly visits to hopefully be more manageable for families.
Healio: Are there any particularly surprising or significant findings you would like to spotlight?
Kim: We were excited to see that when we increased the treatment dose from 2 mg in our previous study to 4 mg in this study that the treatment remained similarly safe with the same rate of side effects, simple mouth itch again the most common side effect, and not having any significant side effects requiring epinephrine with SLIT.
We saw strong desensitization with patients increasing from a pretreatment threshold for peanut reaction of one-sixth of a peanut (48 mg) up to nine peanuts (2,723 mg) after treatment. A third of patients completed the entire 16-peanut challenge without any symptoms at all.
We also used a first-of-its-kind strategy for seeing what happens after treatment is completed and SLIT is stopped. Using a cutoff of about three peanuts (800 mg) to represent clinically meaningful protection from accidental ingestions, our data shows that it would take on average 22 weeks before someone falls below this threshold and becomes reactive again.
Healio: The participants ranged in age from about 2 to about 12 years. Did you see any differences between patients based on age?
Kim: For this study, we did not divide up the group by age. However, our results in this 2- to 12-year-old group were better than the SLIT study done at Johns Hopkins in adolescent patients, which was better than the CoFAR SLIT study in teenagers and young adults, pointing to a likely age effect. We recently completed a study in 1- to 4-year-old kids to look at this specific question and are finalizing the results right now.
Healio: How can doctors use these findings to improve their care?
Kim: Our data shows that peanut SLIT could be a safe option for treating peanut allergy for those patients who cannot tolerate or do not want to use OIT. The data also shows us that it might not be a cure for peanut allergy, but the treatment effect does seem to last. So, if doses are missed, patients will likely stay protected for a period of time.
Healio: SLIT appears to offer comparable effectiveness to OIT. Are there any other advantages?
Kim: A key caveat in comparing SLIT and OIT is assuming that patients are looking for a buffer of protection against accidental ingestions, as opposed to freely eating peanut or even curing the allergy. On this background, I would say that SLIT can offer essentially the same level of protection as OIT.
However, I would also say that SLIT is far safer than OIT, with extremely rare multisystem reactions and no reactions requiring treatment with epinephrine, both of which do occur with OIT. Also, no patients stopped SLIT due to side effects, whereas dropouts have been seen with OIT.
Just as important as the better safety, though, is the much simpler administration with SLIT. There are far fewer clinic visits, as described above. There is no prepping of the medication like in OIT. Instead, you just pull it from the fridge and pump it. We only observe for 30 minutes with SLIT, and we do not restrict exercise or other activities during dosing, like is required with OIT. We also do not require a full stomach or dosing with a meal. All of this provides a lot more flexibility on how and when to dose with SLIT compared with OIT.
Considering the caveat above, I will say that OIT tends to lead to higher reaction thresholds than SLIT. So, if maximum thresholds are the patient’s goal, OIT may be a better option. But for many if not most patients who do not care for the taste, texture or smell of peanut, the higher milligram threshold does not actually provide any practical real-world difference, especially considering the tradeoff with safety and administration.
Healio: What is the next step in this research?
Kim: Some key next steps will be seeing if this data can be replicated in larger multi-center studies, seeing if there might be a best age for starting treatment, and seeing if the SLIT concept can be used for other foods or multiple foods.
References:
- Fleischer DM, et al. J Allergy Clin Immunol. 2013;doi:10.1016/j.jaci.2012.11.011.
- Jones SM, et al. Lancet. 2022;doi:10.1016/S0140-6736(21)02390-4.
- Narisety SD, et al. J Allergy Clin Immunol. 2014;doi:10.1016/j.jaci.2014.11.005.
For more information:
Edwin H. Kim, MD, MS, can be reached at edwinkim@email.unc.edu.