L33:
Omalizumab As Adjuvant Therapy in Chemotherapy Desensitization
Monday, March 5, 2018
South Hall A2 (Convention Center)
David I. Hong, MD FAAAAI
Rationale: Rapid drug desensitization is a highly effective method of inducing a temporary state of tolerance in patients with IgE-mediated chemotherapy reactions. However, a small minority of patients continue to have significant reactions including anaphylaxis despite best efforts to desensitize, even with the addition of supplemental antihistamines and/or lengthening the infusion protocol. The potential role of omalizumab in treating drug allergy has thus far been unexplored despite its known clinical role in treating allergic asthma and chronic urticaria.

Methods: Patients with a history of persistent breakthrough reactions during desensitization despite adding supplemental antihistamines and/or lengthened infusion protocols were enrolled for a 12-week open label trial of omalizumab administered every 4 weeks x 3 treatments. During this period, patients would continue their chemotherapy regimen as prescribed by their oncologist, and post-desensitization surveys were given to determine if breakthrough reactions continued or not.

Results: The study was ended early due to slow recruitment. Of the five patients enrolled, one dropped out due to cytokine storm-like reaction and another due to disease progression on their chemotherapy. Omalizumab did not completely abrogate breakthrough reactions in all patients, but all patients who completed the study saw, at a minimum, significant mitigation of breakthrough reaction symptoms.

Conclusions: Despite not meeting our enrollment goals, omalizumab did prove effective at eliminating or significantly reducing the severity of symptoms in patients who have persistent breakthrough reactions with rapid drug desensitization. We propose that omalizumab is a useful adjunct in patients who have persistent mast cell-mediated reactions resistant to desensitization.