Monitoring and Safety Considerations With Anti-CD20 Therapy in IgG4-RD

In "Monitoring and Safety Considerations With Anti-CD20 Therapy in IgG4-RD," the panel explores the practical demands of keeping patients safe on B-cell depletion.

Dr. Culver then asks how he monitors patients while waiting for a possible repeat infusion at 4 to 6 months. Dr. Della Torre notes that, based on clinical trial data, relapse is rarely seen while patients remain B-cell depleted. He cautions that this benefit must be balanced against the side effects of long-term immunosuppression. When he gives a first course without planned maintenance, he uses a multidimensional approach. It combines clinical expertise, patient symptoms, and serologic biomarkers. These biomarkers are imperfect, so he tracks them according to the organs involved.

Radiology is central, but he limits radiation exposure whenever possible. He prefers ultrasound or MRI and uses PET only in selected cases. His team also uses flow cytometry to measure circulating B cells. Their work shows that activated B cells called plasmablasts tend to reappear before relapse, often by a few months. He does not retreat at the first sign of repopulation. Instead, it signals immune reconstitution and prompts closer monitoring.

The biggest safety concern with B-cell depletion, Dr. Della Torre explains, is infection. Patients generally tolerate rituximab well and appreciate not taking daily pills. However, its effect on the immune system varies. Immunosuppression in an 18-year-old differs from that in a 45- to 50-year-old. Infection risk is also higher in patients with existing comorbidities. Rituximab cannot be withdrawn if an infection, another complication, or unplanned surgery occurs. He contrasts this with subcutaneous and oral agents used in other immune diseases, which are easier to manage.

Dr. Culver adds that she counsels patients about hypersensitivity reactions and anaphylaxis, which is why premedication is used. She also discusses infection risk, vaccination, and avoiding reactivation of latent infections. Dr. Della Torre adds hypogammaglobulinemia, which he increasingly sees with long-term depletion. Some patients then need monthly intravenous immunoglobulin replacement. That means additional visits and infusions on top of rituximab, a burden that grows the longer patients remain on therapy.

In "Anti-CD19 B-Cell Depletion in IgG4-RD: Phase 3 Data and Practice," Dr. Katz and Dr. Della Torre will discuss the first registrational phase 3 trial in this disease and early experience in clinic.