Thoracic Imaging of Non-Small Cell Lung Cancer Treated With Anti-programmed Death Receptor-1 Therapy.

Purpose: Treatment with anti-programmed death receptor-1 (PD-1) therapeutics can lead to unconventional responses and side effect profiles due to their potentiating effects on the immune system. Here we evaluate the radiologic manifestations of anti-PD-1 therapy in the chest in patients with non-small cell lung cancer (NSCLC) receiving anti-PD-1 therapy.

Materials And Methods: A retrospective review of real-world clinical practice was conducted of all the patients with NSCLC receiving anti-PD-1 therapy at our institution between 2013 and 2016. All patients without adequate clinical or radiologic follow-up data in the electronic medical records were excluded. Imaging examinations for all patients deemed by their thoracic oncologists to have radiologic pseudoprogression or therapy-associated pneumonitis were reviewed by experienced thoracic radiologists.

Results: A total of 166 patients with NSCLC had available clinical and imaging data for retrospective review. Of these patients, 4 (2%) were considered to have radiologic pseudoprogression, 3 of which manifested as increased tumor size and 1 of which manifested with new lesions. A total of 5 patients (3%) were clinically deemed to have pneumonitis attributable to anti-PD-1 therapy, 4 of which had radiologic manifestations on computed tomography.

Conclusion: Radiologic pseudoprogression and drug-induced pneumonitis are uncommon but important manifestations of anti-PD-1 therapy on thoracic imaging.