Success limited in oral immunotherapy for adults with food allergies
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Key takeaways:
- Seven of the 30 patients in the cohort discontinued oral immunotherapy because they moved, were pregnant or lacked time or energy.
- Ten of the patients discontinued care due to adverse events.
Adults experienced limited success with oral immunotherapy for food allergies, with about half of a cohort halting treatment within 2 years, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
However, OIT still increased long-term tolerance, and adverse events were mostly mild, Tuuli Thomander, MD, doctoral program in clinical research, University of Helsinki, and colleagues wrote.
The study included 30 adults aged 18 to 64 years who were treated with OIT for milk (n = 12), peanut (n = 14) and egg (n = 4) allergy. All patients also had an oral food challenge, except for two patients in the milk group.
Also, 14 of the patients completed 2 or more years of OIT, including seven (58%) of the milk group, five (36%) of the peanut group and two (50%) of the egg group. The other 16 patients stopped OIT before reaching 2 years.
The patients in the milk group who completed 2 or more years experienced a 50-fold increase in how much milk they could tolerate. The peanut group experienced a 600-fold increase and the egg group experienced a 420-fold increase in their tolerated doses too.
Seven of the 16 patients who discontinued OIT did so due to social reasons such as moving to a different city or abroad, pregnancy or a lack of time or energy for treatment. Also, ten patients said they discontinued OIT because of adverse events, including one diagnosed with eosinophilic esophagitis and one who experienced repeated infections.
The patients who discontinued treatment in the milk group were younger (median age, 25 years) than those who continued treatment (median age, 36.5 years; P < .05).
Adverse events among the patients who continued treatment for 2 years or longer included local itching or swelling (n = 13), itching of the mouth or throat (n = 11), angioedema (n = 6), eczema (n = 9), generalized urticaria (n = 2), abdominal pain (n = 7), nausea (n = 6), vomiting (n = 2), and diarrhea (n = 1).
Also, 10 of these patients reported asthma symptoms, two said that they had to use an epinephrine injection and four visited the ED due to the OIT.
Specifically, in the group that continued treatment for 2 or more years, 29% of the patients with milk allergy reported epinephrine use, but none of the patients in the peanut or egg groups did. Also, 43% of the milk group and 20% of the peanut group visited the ED due to allergy, but none of the egg group did.
The patients who stopped treatment before 2 years had at least double the pre-fractional exhaled nitric oxide levels of the patients who continued OIT for 2 or more years.
Medians included 71.75 ppb for those who continued care and 9.05 ppb for those who did not in the milk group; 30.9 ppb for those who continued care and 15.65 ppb for those who did not in the peanut group; and 109.75 ppb for those who continued care and 23.4 ppb for those who did not in the egg group.
The median maximum tolerated OIT dose of peanut was 600 mg, or twice what is considered accidental exposure to a single peanut.
The medium maximum tolerated OIT dose of milk, including 1,500 mg of protein, was 8.3 times the accidental exposure dose of 6 mL with 180 mg of protein.
Median IgE levels were higher for the patients with peanut (421 kU/L) and egg (1,162.5 kU/L) who stopped OIT compared with those who continued with therapy (peanut, 136.5 kU/L; egg, 551 kU/L). However, the patients who halted OIT for milk had a lower median IgE level (1,104.5 kU/L) than those who continued therapy (2,439.5 kU/L).
The median value of 1,050 mg of egg-white protein or a third of an egg white achieved in this study exceeded accidental exposures to a quarter egg, or 1,500 mg of protein, as well.
With 28 of the 30 patients in the full cohort having an OFC, the researchers did not report any statistically significant differences in the OFCs of the patients who did or did not continue OIT through 2 years or longer.
Despite the limited percentage of adults who continued OIT for 2 years or longer, the researchers said, the treatment still increased tolerance with mostly mild adverse events and pre-FeNO best predicting success.
Perspective
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With so few OIT studies in adults, even this small group adds significantly to knowledge about OIT and “long-term” outcomes. It is significant also that the study focused on staple dietary foods, namely milk and egg, as well as peanut.
It has to be appreciated that almost all of the participants were very sensitive at the start, with most reacting to what we would call “trace” exposure and having very strongly positive allergy tests. Seeing 50% “make it” to 2 years with final dosing with substantial amounts of the food is, in my view, quite good given their allergy characteristics.
The study reflects the troubles experienced in the OIT pathway, such as multiple allergic reactions, including some severe ones, and development of chronic allergic gut inflammation. The study also confirmed in this group that milk can be particularly tough to treat. Even those who made it to 2 years had substantial rates of reactions, treatment with epinephrine and ED visits.
An important takeaway is that discontinuation was attributed to both substantial side effects but also the very strong burden of treatment, which carries its own impact. Undergoing OIT means following daily regimens as well as caution about factors such as illness or exercise that can enhance reactions. OIT is a huge commitment.
It would be interesting to know what happens for this group over the next several years and their own impressions of their efforts and outcomes. Although it is trite to say that we need more studies and larger numbers, we do, and the data here are helpful in adding perspective for having shared decision-making conversations with adults about the nuances of this therapy. But the small study size here limits conclusions about factors that predict the long-term outcomes.
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