Intravenous Cyclophosphamide Therapy for Anti-IFN-Gamma Autoantibody-Associated Mycobacterium abscessus Infection

Introduction. Anti-interferon-gamma (IFN-) autoantibodies are increasingly recognized as a cause of adult-onset immunodeficiency (AOID) worldwide. These patients are susceptible to various intracellular pathogens especially nontuberculous mycobacteria. Most of the patients have a refractory clinical course. Herein, we report the use of immunotherapy with pulse intravenous cyclophosphamide (IVCY) in patients who had progressive, refractory Mycobacterium abscessus infection. Method. We included patients, seen at Srinagarind Hospital, Thailand, infected with M. abscessus, who had received 3 courses of parenteral antibiotics within the last 12 months and who received pulse IVCY with a tapering dose of prednisolone. Results. There were 8 AOID patients who met the criteria and received pulse IVCY between January 2011 and December 2015. One patient was lost to follow-up after 5 courses of IVCY: he had died at home 3 months later. Five patients had favorable outcomes: 2 were able to discontinue NTM therapy, and 3 had stable disease and were on NTM treatment without hospitalization for parenteral antibiotics. Two patients relapsed and needed hospitalization. The IFN- Ab titers among the 7 patients were significantly decreased during treatment, and the median initial antibody titer started at 200,000 and then decreased to 5,000 after 2 years of treatment (P<0.0001). The antibody titer reduction among responsive vs. nonresponsive patient was significantly different after 6 months of treatment: the median antibody titer was 5,000 and 100,000, respectively (P=0.0467). Conclusion. IVCY therapy might be an alternative treatment for AOID patients infected with M. abscessus and refractory to antimycobacterial therapy.