Nontuberculous Mycobacterial Infections in the Setting of Immune Checkpoint Inhibitor Therapy: A Case Series

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy. While ICIs have shown efficacy across a range of malignancies, they have also been associated with immune-related adverse events (irAEs) and there is increasing concern that ICIs may predispose patients to opportunistic infections. We report six cases of clinically significant nontuberculous mycobacterial (NTM) infections occurring during or after ICI therapy. Key findings include the prevalence of underlying lung disease in patients diagnosed with NTM infection (including primary pulmonary malignancy or metastases), predominance of anti-PD-1/PD-L1 exposure in our cohort, wide range of NTM species identified, wide temporal windows between ICI therapy and NTM infection, and overall good outcomes after NTM-directed therapy with four of five patients who received NTM-directed therapy alive at one year after NTM diagnosis. We recommend that clinicians maintain a high index of suspicion for NTM infections in the differential for patients who have received ICI therapy and we recommend ongoing investigation into the potential correlation between ICI therapy and NTM infection.