Background: Patients with stage IIIA (N2 or T4N0) are potentially curable but median overall survival is only around 15 months and complete pathologic response with conventional chemotherapy (CT) is no more than 9%. Methods: A Phase II, single-arm, open-label multicenter study of resectable stage IIIA N2-NSCLC adult patients with CT plus IO as a neoadjuvant treatment: three cycles of Nivolumab (NV) 360mg IV Q3W + paclitaxel 200mg/m2 + carboplatin AUC 6 IV Q3W followed by adjuvant NV treatment for 1 year. After complete neoadjuvant therapy, tumor assessment is performed prior to surgery. Surgery is performed in the 3rd or 4th week after day 21 of the third cycle of neoadjuvant treatment. The study aims to recruit 46 pts. The primary endpoint is Progression-Free Survival (PFS) at 24 months. Efficacy is explored using objective pathologic response criteria. We present final data on all patients included in this study that underwent surgical assessment. Results: At the time of submission, 46 pts had been included and 41 had undergone surgery. CT-IO was well-tolerated and surgery was not delayed in any patient. None of the pts withdrew from the study preoperatively due to progression or toxicity. 41 surgeries had been performed and all tumors were deemed resectable, with R0 resection in all cases. 34 pts (83%) achieved major pathologic response (MPR) (CI 95% 71-95%), and 24 (71%) of them had a complete pathologic response (CPR) (CI 95% 54-87%). Downstaging was seen in 90% (CI 95% 81-100%) of cases. By RECIST, 29 pts (71%) (CI 95% 56-85%) had partial response and 3 (7%) (CI 95% 0-16%) complete response. Conclusions: This is the first multicentric study to CT-IO in the neoadjuvant setting in stage IIIA. Neoadjuvant CT-IO with nivolumab in resectable IIIA NSCLC yields a high complete pathologic response rate that has never been seen previously and unsuspected by RECIST criteria. Preliminary correlative analyses in blood samples are included in a separate abstract. EudraCT Number: 2016-003732-20. Clinical trial information: NCT 03081689.