IgG4-related disease can strike any organ system
EXPERT ANALYSIS FROM THE WINTER RHEUMATOLOGY SYMPOSIUM
Treatment with rituxumab
Glucocorticoids remain the first-line therapy in IgG4-related disease, but it’s essential to bear in mind that their long-term efficacy in this immune-mediated fibroinflammatory disease is the exception rather than the rule, Dr. Stone said at the symposium.
Dr. Stone was a coauthor of an international expert consensus statement on the treatment of IgG4-related disease (IgG4-RD), which emphasized that point (Arthritis Rheumatol. 2015 Jul;67[7]:1688-99).
“I typically start with prednisone at 40 mg/day, and there’s a dramatic response in these patients. Then I taper them off after 2-3 months. If 2-3 months doesn’t put them into a long-term sustained remission, it’s time to go to something else,” said Dr. Stone.
So what’s the next move, then, after steroids fail? Dr. Stone was a pioneer in the strikingly successful use of B cell depletion via rituximab (Rituxan) in patients with IgG4-RD. First he and his coinvestigators demonstrated that this off-label use of rituximab led to rapid clinical and histologic improvement (Ann Rheum Dis. 2015 Jun; 74[6]:1171-7), then they showed it also causes levels of circulating plasmablasts, serum IgG4, and biomarkers of fibrosis to plunge, suggesting B cell depletion may halt the destructive process of collagen deposition that characterizes this immune-related disease (Ann Rheum Dis. 2015 Dec;74[12]:2236-43). They have also reported that patients with very elevated baseline serum IgG4 levels are at more than sixfold increased risk of relapse at a median of 244 days from their first rituximab infusion (Rheumatology [Oxford]. 2016 Jun;55[6]:1000-8).
The success with rituximab is just one example of how improved understanding of the pathophysiology of IgG4-RD has opened the door to novel treatments. Dr. Stone is the lead investigator in an ongoing phase II, open-label study in which 15 patients with active IgG4-RD will receive intravenous XmAb5871 every 2 weeks for 6 months to evaluate the effect on the IgG4-RD Responder Index. XmAb5871 is a monoclonal antibody that binds to CD19 and FCgammaRIIb in order to downregulate activated B cells and plasmablasts. It is also being developed for treatment of systemic lupus erythematosus.
Dr. Stone and his coinvestigators are working on a therapeutic approach to IgG4-RD that targets antigen presentation by activated B cells to CD4+ cytotoxic T cells at sites of disease. These CD4+ cytotoxic T cells contain signaling lymphocyte activation molecule F7 (SLAMF7) as a surface marker. Elotuzumab (Empliciti), an immunostimulatory humanized monoclonal antibody targeting SLAMF7, is already on the market for treatment of multiple myeloma, he noted.
Dr. Stone reported receiving IgG4-RD-related research funding from and serving as a consultant to Genentech and Xencor, which is developing XmAb5871.
