Preliminary evaluation of serial interferon-gamma releasing assay testing in NSCLC patients treated with immune checkpoint inhibitors

<b>Background:</b> Recently, cancer immunotherapy using immune checkpoint inhibitors (ICIs) has received remarkable attention. While patients can benefit from these drugs, immune-related adverse events and infections such as tuberculosis are potential sequelae. In this study, we aimed to evaluate the association between the interferon-gamma releasing assay (IGRA) conversion rate and the incidence of active tuberculosis during immunotherapy. <b>Methods:</b> We prospectively assessed IGRA in NSCLC patients who were receiving ICIs, at diagnosis and 6 and 12 months after treatment. We evaluated patients with positive IGRA results for active tuberculosis with CT scans.(clinical trial number:UMIN36533) <b>Results:</b> Fifty-nine patients completed serial IGRA testing. At baseline, eight (13.6%) patients had a positive IGRA, 50 (84.7%) had a negative IGRA, and one (1.7%) had an indeterminate IGRA. Two (3.4%) patients showed a negative conversion of IGRA. During immunotherapy, only one patient showed a positive conversion of IGRA. One patient with a positive conversion of IGRA and one with a sustained negative IGRA developed active pulmonary tuberculosis during immunotherapy. <b>Conclusions:</b> This preliminary study revealed that 1.7% (1/59) patients had positive conversions of IGRA and that it correlated with the development of active tuberculosis. However, the clinical utility of IGRA screening remains undetermined in light of a case with a negative conversion, and further study is warranted. Nevertheless, physicians should pay attention to the potential development of tuberculosis during immunotherapy with ICIs.