FCER1A and Autoimmunity: At 200 mg twice daily, fenebrutinib improved disease activity in patients with and without markers of type IIb autoimmunity at baseline (BHRA+, IgG-anti-FcεRI+ and low serum IgE (<43 IU ml−1)36), indicated by similar UAS7 improvements for each subgroup compared to placebo (Fig. 3a and Extended Data Fig. 5).