Long-Term Outcome of Peanut Oral Immunotherapy Facilitated Initially by Omalizumab.

BACKGROUND: We successfully used omalizumab to facilitate peanut oral immunotherapy (OIT) in children with reactivity to ≤50mg peanut protein and with high peanut IgE (median, 229 kU/L). OBJECTIVE: We report on long-term OIT outcomes in these patients, including dosing changes, adverse events, peanut immunoglobulin changes, and quality of life (QoL). METHODS: Patients were followed for up to 72 months (67 months of maintenance). Outcomes were collected on peanut dose amount, form, and frequency, as well as adverse events, (QoL), and laboratory studies. RESULTS: Of 13 patients initially enrolled, 7 patients (54%) continued on peanut OIT through month 72; 6 (46%) discontinued therapy because of adverse reactions. Maintenance peanut protein dose varied between 500 and 3500mg. Most patients consumed different peanut-containing products. All patients experienced at least 1 adverse event, and 1 patient developed eosinophilic esophagitis. Peanut-IgE, Arah1-IgE and Arah2-IgE, peanut-SPT, peanut-IgE:IgE ratio, and Arah2-IgE:Arah2-IgG4 ratio decreased on OIT. Peanut-IgG4, Arah1-IgG4, and Arah2-IgG4 initially increased on OIT and then decreased, though not falling to baseline levels. In patients who stopped OIT, there was a trend for reversal of these biomarker changes. Higher peanut-IgE and Arah2-IgE at study month 12 were associated with discontinuation. Patient and parent QoL improved from baseline, even in patients who discontinued OIT. CONCLUSIONS: Although adjunctive omalizumab allowed for faster and successful desensitization in patients with high peanut-IgE, almost half of patients discontinued OIT within 72 months because of reactions. Patients who stopped therapy had higher month 12 peanut-IgE and Arah2-IgE. It is possible that these patients might benefit from longer omalizumab administration.

Omalizumab facilitates rapid oral desensitization for peanut allergy.

BACKGROUND: Peanut oral immunotherapy is a promising approach to peanut allergy, but reactions are frequent, and some patients cannot be desensitized. The anti-IgE medication omalizumab (Xolair; Genentech, South San Francisco, Calif) might allow more rapid peanut updosing and decrease reactions. OBJECTIVE: We sought to evaluate whether omalizumab facilitated rapid peanut desensitization in highly allergic patients. METHODS: Thirty-seven subjects were randomized to omalizumab (n = 29) or placebo (n = 8). After 12 weeks of treatment, subjects underwent a rapid 1-day desensitization of up to 250 mg of peanut protein, followed by weekly increases up to 2000 mg. Omalizumab was then discontinued, and subjects continued on 2000 mg of peanut protein. Subjects underwent an open challenge to 4000 mg of peanut protein 12 weeks after stopping study drug. If tolerated, subjects continued on 4000 mg of peanut protein daily. RESULTS: The median peanut dose tolerated on the initial desensitization day was 250 mg for omalizumab-treated subjects versus 22.5 mg for placebo-treated subject. Subsequently, 23 (79%) of 29 subjects randomized to omalizumab tolerated 2000 mg of peanut protein 6 weeks after stopping omalizumab versus 1 (12%) of 8 receiving placebo (P < .01). Twenty-three subjects receiving omalizumab versus 1 subject receiving placebo passed the 4000-mg food challenge. Overall reaction rates were not significantly lower in omalizumab-treated versus placebo-treated subjects (odds ratio, 0.57; P = .15), although omalizumab-treated subjects were exposed to much higher peanut doses. CONCLUSION: Omalizumab allows subjects with peanut allergy to be rapidly desensitized over as little as 8 weeks of peanut oral immunotherapy. In the majority of subjects, this desensitization is sustained after omalizumab is discontinued. Additional studies will help clarify which patients would benefit most from this approach.