Defining Treatment Success, Switching Therapy, and Managing IgG4-RD Complications

In "Defining Treatment Success, Switching Therapy, and Managing IgG4-RD Complications," the panel explores how clinicians judge whether treatment is working and what to do when it is not.

Dr. Della Torre argues that treatment success varies by patient. It may mean immunologic improvement, radiologic resolution, resolution of clinical manifestations, or flare prevention. A combination of these goals is most realistic. He might accept low-grade disease activity in a patient whose comorbidities would worsen with immunosuppression. That would not apply to rapidly declining kidney function or neurologic disease. Recovering organ function is itself a success. Overall, success means balancing lower disease activity against treatment side effects.

Switching has been uncommon, he explains, because glucocorticoids and rituximab have been the only real options. However, he has seen rituximab become less effective with repeated infusions. Possible reasons include neutralizing antibodies or reduced depletion of B cells in tissue. These patients relapse earlier than before. He then switches to a fully humanized anti-CD20 antibody or adds an immunosuppressant such as mycophenolate. For atopic features such as asthma, rhinitis, or nasal polyps, he adds another monoclonal antibody. In pachymeningitis, he has given rituximab intrathecally rather than intravenously.

On complications, Dr. Katz says he does not manage them alone. Multidisciplinary care is essential because damage often falls outside rheumatology. He relies on oculoplastic surgeons for irreversible diplopia from orbital disease. Ear, nose, and throat specialists help with persistent chronic sinusitis after sinonasal disease, using topical therapy and sometimes surgery. He also works closely with pancreatologists, given the high burden of pancreatic insufficiency.

Dr. Katz monitors treatment complications himself. In patients receiving B-cell depletion, he tracks immunoglobulin levels for hypogammaglobulinemia. He reviews vaccines at nearly every visit and vaccinates before depletion when possible. Sometimes a more pressing comorbidity must be addressed before the disease. Dr. Culver adds bone health, noting that the risk of osteoporosis in these patients is not yet well quantified.

Up next, in "Malignancy Risk in IgG4-RD: Interpreting Conflicting Evidence," Dr. Katz and Dr. Della Torre unpack one of the most debated questions in the field.