Principia Biopharma Inc. announced that the first patient was dosed in an open label two-arm trial to evaluate rilzabrutinib in IgG4-related disease (RD). This multicenter Phase 2A trial is anticipated to enroll approximately 25 patients with active IgG4-RD in two arms, rilzabrutinib with glucocorticoids or glucocorticoids only. Patients who meet all the inclusion criteria after completion of the four-week screening period will be randomized in a 3:1 ratio to the rilzabrutinib with glucocorticoids arm or the glucocorticoids only arm. The main treatment period is 12 weeks, and patients may then be eligible to enter a treatment extension period of 40 weeks, followed by a four-week safety follow-up period. The primary endpoint of the trial is the proportion of patients who achieve complete remission at week 12 with no glucocorticoid use at Week 4 for the rilzabrutinib arm and week 12 for the glucocorticoids arm.