Peanut oral immunotherapy plus omalizumab for 24 weeks safely induces
tolerance at 48 weeks in allergic adults (The OPAL Study)
Abstract
Background Peanut oral immunotherapy (POIT) with or without
omalizumab can improve tolerance in peanut-allergic children. Data
regarding adults are limited. We evaluated the safety and efficacy of
omalizumab plus POIT over 48 weeks in adults. Methods Adults
allergic to ≤300mg peanut protein following double-blind,
placebo-controlled peanut challenges (DBPCPCs) received omalizumab 300mg
q4 weeks x 6 doses. Daily POIT commenced at Week 12 (25mg), increasing
to a maximum 300mg at Week 24, followed by 300mg daily. Participants
underwent DBPCPCs up to 1000mg at Weeks 24 and 48. Primary outcome
(tolerance of ≥300mg peanut protein) was analysed by intention-to-treat.
Changes from baseline and from Week 24 were analysed using paired
t-tests. Results Of 25 patients treated (median age 24 years,
mean eliciting dose 30mg, mean skin prick [SPT] diameter 10.6mm),
all tolerated ≥300mg peanut protein at Week 24, and 22 (88%) at Week 48
(p=0.08; 2 withdrew due to anxiety, 1 lost to follow up), Food Allergy
Quality of Life score improved (mean change -29.6 [scale 0-174],
p<0.05), and SPT diameter decreased (mean 3.5mm,
p<0.0001). Basophil activation by total peanut protein, Ara H2
and Ara H6 decreased significantly at Week 24 (mean -1.2% to -48.0%,
all p<0.05) but not at Week 48. Of 169 allergic reactions to
POIT, 61 (36.1%) were treated with antihistamine and three (1.8%) with
adrenaline. Adverse event (AE) rate for a moderate-severe, POIT-related
AE was 0.002/dose [Number needed to harm (NNT
H)=500]. Conclusion POIT plus omalizumab for
24 weeks safely induced tolerance of 300mg peanut protein over 48 weeks
in peanut-allergic adults.