Background: Severe malignant airway obstruction (SMAO) is a life-threatening form of non-small cell lung carcinoma (NSCLC). Objectives: To determine the efficacy and safety of para-toluenesulfonamide (PTS) intratumoral injection in NSCLC-SMAO. Methods: Ninety patients with NSCLC-SAO received repeated courses of PTS intratumoral injection until tumor sizes had reduced by 50% or greater. Primary endpoint was objective alleviation rate, assessed by chest computed tomography (CT) and bronchoscopy, at day 7 and 30 following final dosing. Secondary endpoints included airway obstruction, spirometry, quality-of-life and survival time. Results: In full-analysis set (N=88), using RECIST criteria, PTS treatment resulted in a significant objective alleviation rate [chest CT: 59.1% (95%CI: 48.1%-69.5%), bronchoscopy: 48.9% (95%CI: 38.1%-59.8%) at day 7; chest CI: 43.2% (95%CI: 32.7%-54.2%), bronchoscopy: 29.6% (95%CI: 20.3%-40.2%) at day 30]. There was a remarkable increase in FVC (mean difference: 0.35 liters, 95%CI: 0.16-0.53 liters), FEV1 (mean difference: 0.27 liters, 95%CI: 0.07-0.48 liters), Baseline Dyspnea Index (mean difference: 64.8%, 95%CI: 53.9-74.7%) and Functional Assessment of Cancer Therapy-Lung Cancer Subscale (mean difference: 6.9, 95%CI: 3.8-9.9) at day 7 post-treatment. We noted significantly reduced prevalence of atelectasis (by 42.9%) and Eastern Cooperative Oncology Group physical performance scale (mean difference: 7.2, 95%CI: 3.9-10.5). Median survival time was 394 days in full-analysis set and 460 days in per-protocol set. Adverse events were reported in 64.0% of subjects. Seven severe adverse events (7.9%) were reported, of which three led to death (drug-related in one case). Conclusion: PTS intratumoral injection is effective and well tolerated for palliative therapy of NSCLC-SMAO. (C) 2016 Elsevier Ireland Ltd. All rights reserved.