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

INTRODUCTION: Anti-interferon-gamma (IFN-γ) 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-γ 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.