RT Journal Article SR Electronic T1 Comparison Between 18F-FDG PET–Based and CT-Based Criteria in Non–Small Cell Lung Cancer Patients Treated with Nivolumab JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 990 OP 998 DO 10.2967/jnumed.119.233056 VO 61 IS 7 A1 Giovanni Rossi A1 Matteo Bauckneht A1 Carlo Genova A1 Erika Rijavec A1 Federica Biello A1 Simone Mennella A1 Maria Giovanna Dal Bello A1 Giuseppe Cittadini A1 Paolo Bruzzi A1 Roberta Piva A1 Valentina Ceriani A1 Gianmario Sambuceti A1 Egesta Lopci A1 Silvia Morbelli A1 Francesco Grossi YR 2020 UL http://jnm.snmjournals.org/content/61/7/990.abstract AB Because of the peculiar mechanism of action of immune checkpoint inhibitors (ICIs), evaluation of the radiologic response to them in solid tumors presents many challenges. We aimed to compare evaluation of the first response to nivolumab by means of CT-based criteria with respect to 18F-FDG PET response criteria in non–small cell lung cancer (NSCLC) patients. Methods: Seventy-two patients with advanced NSCLC were recruited in a single-institution ancillary trial within the expanded-access program (NCT02475382) for nivolumab. Patients underwent CT and 18F-FDG PET at baseline and after 4 cycles (the first evaluation). In cases of progressive disease, an additional evaluation was performed after 2 further cycles to confirm progression. We evaluated the treatment response on CT using RECIST 1.1 and the immune-related response criteria (irRC) and on 18F-FDG PET using PERCIST and immunotherapy-modified PERCIST. The concordance between CT- and PET-based criteria and the capability of each method to predict overall survival were evaluated. Results: Forty-eight of 72 patients were evaluable for a first response assessment with both PET- and CT-based criteria. We observed low concordance between CT- and PET-based criteria (κ-value of 0.346 and 0.355 between PERCIST and imPERCIST and RECIST, respectively. κ-value of 0.128 and 0.198 between PERCIST and imPERCIST and irRC, respectively). Regarding overall survival, irRC could more reliably distinguish responders from nonresponders. However, thanks to the prognostic value of partial metabolic response assessed by both PERCIST and immunotherapy-modified PERCIST, PET-based response maintained prognostic significance in patients classified as having progressive disease on the basis of irRC. Conclusion: Even though the present study did not support the routine use of 18F-FDG PET in the general population of NSCLC patients treated with ICIs, the findings suggest that metabolic response assessment has added prognostic value, potentially improving therapeutic decision making.