Anti-TPO IgG/Total IgE Ratio: Biomarker for Omalizumab Response Prediction in Chronic Spontaneous Urticaria.

BACKGROUND

According to recently published data, low total IgE, elevated IgG-anti-TPO, and a high IgG-anti-TPO/total IgE ratio are good biomarkers for subtype IIb autoimmune chronic spontaneous urticaria (CSU), which is frequently refractory to antihistamines and omalizumab.

OBJECTIVES

The aim of the study was to evaluate IgG-anti-TPO/total IgE ratio's utility in omalizumab response prediction.

METHODS

Retrospective study of CSU patients treated with omalizumab at a UCARE between January 2009 and February 2022. Patients were grouped according to response in the first 16 weeks of treatment: responders UAS7 < 7 versus partial/non-responders UAS7≥7. Total IgE, IgG-anti-TPO, and IgG-anti-TPO/total IgE ratio were compared. Other inflammatory biomarkers - eosinophils, basophils, C-reactive protein, erythrocyte sedimentation rate, and d-dimer - were analyzed.

STATISTICAL ANALYSIS: SPSS® (v25.0), p < 0.05 statistically significant.

RESULTS

Total of 175 patients, 140 (80%) women, median age 49 [9-88] years, mean CSU duration pre-omalizumab 5.6 ± 8.2 [0-54] years, omalizumab duration 3.2 ± 2.5 [0-12] years. 116 (66%) had angioedema, 77 (44%) inducible chronic urticaria, 60 (34%) atopy, 24 (14%) autoimmune disease. With omalizumab 300 mg q4 weeks, 69% were responders and 31% partial/non-responders. Although not reaching significant differences, mean total IgE values were lower and mean IgG-anti-TPO values were higher in partial/non-responders versus responders (152 vs. 242 kU/L, p = 0.207, and 38.3 vs. 25.7 U/mL, p = 0.408, respectively). A higher IgG-anti-TPO/total IgE ratio was significantly associated with poorer response to omalizumab (p = 0.040). A cut-off >0.154 increased 10 times the odd of poorer response [95% CI 4.62-22], AUC 0.872, p < 0.001, with 87.7% sensitivity, although the low specificity (22.4%) does not allow the assumption of response with values <0.154. Other laboratory biomarkers did not show significant differences between partial/non-responders versus responders.

CONCLUSIONS

A high IgG-anti-TPO/total IgE ratio was a good biomarker of poor response to omalizumab in our CSU cohort, with a cut-off >0.154 increasing 10 times the odd of poorer response.