Moreover, four of the nine patients with persistent mast cell-rich synovitis after 6 months of synthetic DMARDs had synovial lymphoid aggregates of CD20-positive B cells and/or CD138-positive plasma cells; in contrast, none of the 11 synovial mast cell-negative patients did, noted Dr. Troum, a rheumatologist at the University of Southern California, Los Angeles, who is in private practice in Santa Monica, Calif.
In theory, if a baseline synovial tissue immune cell profile could be identified that’s predictive of high-level responsiveness to synthetic DMARDs or, conversely, nonresponsiveness, tissue specimens could be used to stratify patients with early RA to different initial treatment strategies. The problem with that is few rheumatologists in the United States – and indeed worldwide – are proficient at performing ultrasound-guided synovial biopsies, according to Dr. Troum.
His description of the London study prompted a question as to whether any of the biologics used in rheumatology can inhibit mast cells. Arthur Kavanaugh, MD, symposium director, said the only agent that comes to mind is imatinib (Gleevec), a tyrosine kinase inhibitor used in the treatment of aggressive systemic mastocytosis as well as for certain leukemias.
“It has a ton of toxicity, though,” said Dr. Kavanaugh, professor of medicine and director of the Center for Innovative Therapy in the division of rheumatology, allergy, and immunology at the University of California, San Diego.
Dr. Troum reported having no financial conflicts regarding his presentation.