Response to Omalizumab Therapy Based on Level of IgE: A Two Year Observational Study (REALITY Study)

Rationale: Omalizumab is indicated for patients with an IgE level between 30-700 IU/mL, but is often used in patients with levels outside recommendations.  Observational study is designed to assess response to anti-IgE therapy based on serum IgE levels, and comparison of response based  on physician’s clinical assessment vs. objective changes in asthma control.

Methods: Asthmatics patients who have received omalizumab therapy for two years were assessed retrospectively for response. Subjects were grouped by their baseline IgE level: [G1(n=80):30-700; G2(n=17):701-1500; and G3(n=26):>1500]. Response rate was identified by two categories: Positive response by Physician’s Global Assessment(PGA), and by Objective Assessment (OA) based on a 50% reduction in at least 3 of the following parameters: asthma exacerbation(AE);steroid-bursts;ER-visits;hospitalizations;increase in FEV₁>200cc; and improved ACT score≥3. All assessments were compared at three time points:16 weeks(P1), 1-year(P2), and 2-years(P3).

Results: During P1, response-rates were:[G1(54%);G2(71%) and G3(46%)] by PGA and [G1(51%);G2(77%) and G3(62%)] by OA. At one-year(P2), the response-rates were:[G1(81%);G2(94%) and G3(89%)] by PGA and [G1(64%);G2(71%) and G3(89%)] by OA. At 2-year (P2), the response-rates were:[G1(80%);G2(82%) and G3(89%)] by PGA and for OA these were:[G1(69%);G2(71%) and G3(77]. Overall response rate at 1-year and 2-year were 85% and 82 respectively by PGI and 70% and 71% by OA.

Conclusions: Overall, 70 to 80% of subjects treated with omalizumab had a good clinical response independently by both subjective and objective assessments. At both 1 and 2-years after initiation of omalizumab-therapy, the overall response-rate was higher in patients with an IgE level >700 IU/mL than patients within recommended dosing range.