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News
Two phase 2 trials suggest that oral BTK inhibitors — rilzabrutinib and zanubrutinib — may offer meaningful, steroid-sparing benefits for patients with IgG4-related disease. In the rilzabrutinib trial, ~70% of patients remained flare-free and off glucocorticoids for up to 52 weeks. A smaller zanubrutinib study showed significant gland shrinkage and reduced disease activity over 24 weeks, with both treatments generally well tolerated.
Two new phase 2 trials published in the Annals of the Rheumatic Diseases are building a compelling case for Bruton tyrosine kinase (BTK) inhibitors as a steroid-sparing strategy in IgG4-related disease (IgG4-RD) — a rare immune-mediated condition that can affect virtually any organ.
In the larger of the two studies, rilzabrutinib (400 mg twice daily) kept roughly 70% of 27 patients flare-free and off glucocorticoids or immunosuppressants through 52 weeks — including those who had previously failed rituximab. A smaller 10-patient trial of zanubrutinib (80 mg twice daily) focused on head and neck disease and found lacrimal gland volume shrank by nearly 47% and submandibular gland volume by 30% at 24 weeks, alongside meaningful drops in disease activity scores and serum IgG4 levels. Both drugs were generally well tolerated, though adverse events led to discontinuation in some patients.
By the Numbers
Why it matters: IgG4-RD has long relied on glucocorticoids and rituximab, both of which carry significant side effects or limitations. These trials suggest oral BTK inhibitors could offer a more targeted, steroid-free path forward — though larger, controlled studies are needed to confirm these early findings.
