Background: Multi-modality treatment provides modest survival benefits for locally advanced non-small-cell lung cancer (NSCLC) patients. Preoperative immunotherapy has continuously been shown to be promising in treating resectable NSCLC. The current study aimed to investigate the activity and safety of the PD-1 inhibitor, toripalimab, with chemotherapy given as neoadjuvant treatment for resectable stage III NSCLC in Asian population. Methods: Eligible patients recruited were aged 18 years or older with histologically confirmed AJCC-defined stage IIIA or T3-4N2 IIIB NSCLC who deemed surgically resectable. Patients received 3 cycles of neoadjuvant treatment with intravenous toripalimab (240 mg), carboplatin (area under curve 5), and pemetrexed (500 mg/m² for adenocarcinoma) or nab-paclitaxel (260 mg/m² for others) on day 1 of each 21-day cycle. Surgical resection was performed 4-5 weeks following the first day of the last cycle of treatment. The primary endpoint was major pathological response (MPR; ≤10% viable tumor cells). Secondary endpoints included pathological complete response (pCR), R0 resection rate, disease-free survival and safety. Paired primary tumor +/- lymph node and blood samples at baseline and surgery were obtained for exploratory study. This study is registered with ClinicalTrials.gov, NCT04304248. Results: Between August 2019 and July 2020, 33 patients (median age: 61, IQR: 56-66; female: 6, 18.2%) were enrolled and received neoadjuvant treatment. 18 (54.5%) patients had squamous cell lung cancer, and 13 (39.4%) had T3-4N2 stage IIIB disease. Two patients refused surgery and one had progressive disease after treatment. 30 (91.9%) patients underwent resection (median interval between neoadjuvant treatment and surgery: 36.5 days, IQR 30-42.5) and all except one achieved R0 resection (29/30, 96.7%). 20 patients (20/30, 66.7%) had an MPR, including 15 patients (15/30, 50.0%) had a pCR in the per-protocol population. Surgical complications included three arrhythmias, one prolonged air leak, and one chylothorax. 24 patients (80.0%) had pathological downstaging following treatment, and complete lymph node clearances (ypN0) were seen in 70.0% (21/30) of patients. The most common grade 3-4 treatment-related adverse events in the intention-to-treat population were anemia (2, [6.0%]). Severe treatment-related adverse event included one (3.0%) patient with grade 3 peripheral neuropathy (Guillain-Barré syndrome) and resulted in surgery cancellation. At the time of data cutoff (Feb 7, 2021), the median duration of follow-up was 4.13 months, and there were no treatment-related deaths. Conclusions: Toripalimab plus platinum-based doublet yields a high MPR rate, manageable treatment-related toxicity, and feasible surgical resection in resectable stage III NSCLC. Ongoing analysis of biomarker will be available at the meeting. Clinical trial information: NCT04304248