184P Clinico-radiological pattern of response to nivolumab in stage IV NSCL: A real life experience over two years

Background: Immune checkpoint inhibitors are novel and effective drugs in the treatment of stage IV non-small cell lung cancer (NSCLC). These drugs are associated with a specific immune-related patterns of response, including cases of pseudoprogression (Seymour L Lancet Oncol 2017) and hyperprogression (as defined as > 50% tumor burden compared with basal CT; Kato S Clin Cancer Res 2017). Methods: Our purpose was to evaluate the pattern of response in a cohort of patients with stage IIIB-IV NSCLC treated with nivolumab in two oncologic units. Radiologic evaluation was correlated with clinical benefit from the treatment in all the series. Results: We overall selected 86 patients, treated between August 2015 and August 2017. 40 patients were excluded because of absence of a target lesion, previous radiotherapy to a target lesion, follow up inferior to three months. 46 patients (12 males, 34 females) were considered for radiological review, made by a senior and a junior radiologists specialized in thoracic imaging. Median age was 68 years (range 49–84). Stage of disease was IIIB in 12 patients, IV in 34 cases. Histology was adenocarcinoma in 23 patients (50%), squamous cell carcinoma in 23 (50%). 31 patients underwent nivolumab as second line treatment, 15 patients in third line or more. Median number of cycles was 8 (range 1–48). After a radiological review according to iRecist criteria, pseudoprogressions were observed in 4 patients (9%); discrepancy between clinical benefit and radiological response occurred usually at first or second evaluation. Median time to pseudoprogression was 6,2 months (5,3–13). One patient experienced hyperprogression, with rapidly decreasing performance status. Tabled 1CharateristicsPatients (total number: 46)Sex Male33 (71,7%) Female13 (28,3%)Pack years 05 (10,9%) ≤3010 (21,7%) >3026 (56,5%) ND5 (10,9%)Stage IIIb12 (26%) IV34 (74%)Histology Adenocarcinoma23 (50%) Squamous cell carcinoma23 (50%)Number of cycles ≤1023 (50%) 10–2010 (21,8%) 20–308 (17,4%) >306 (10,8%)Radiological results Pseudoprogression4 (9%) Hyperprogression1 (2,2%) Open table in a new tab Conclusions: Pseudoprogression in immunotherapy treatment is a rare but possible event in NSCLC treatment. Immunotherapy treatment should be carefully interrupted in patients with clinical benefit. A small percentage of patients do not benefit from immunotherapy and have a rapid progression of disease during the first courses of immunotherapy. Legal entity responsible for the study: Prof. Lorenzo Livi Funding: Has not received any funding Disclosure: All authors have declared no conflicts of interest.