Increasing the T-cell immune response to Mycobacterium tuberculosis with an anti-programmed cell death 1 (anti-PD-1) antibody may ultimately have detrimental effects. We present the case of a patient with advanced non-small cell lung cancer who developed active tuberculosis (TB) after initial treatment with pembrolizumab, an anti-PD-1 antibody. Pembrolizumab was resumed after completing anti-TB treatment, and no relapse of TB was observed clinically or radiologically. Checkpoint inhibitor-related pneumonitis (CIP) is first suspected when a pulmonary shadow presents during treatment with an anti-PD-1 antibody. It is sometimes difficult to diagnose CIP using computed tomographic images alone. Careful testing, including bacterial examinations and bronchoscopic biopsy, should be performed.
Keywords: Mycobacterium tuberculosis; immune checkpoint inhibitor; non-small cell lung cancer; pembrolizumab.