Effects of para-toluenesulfonamide intratumoral injection on pulmonary adenoid cystic carcinoma complicating with severe central airway obstruction: a 5-year follow-up study

Pulmonary adenoid cystic carcinoma (ACC) is a rare type of non-small cell lung carcinoma that may develop life-threatening severe malignant airway obstruction (SMAO). Currently, limited therapeutic approaches exist for ACC-SMAO. We investigated the efficacy and safety of para-toluenesulfonamide (PTS) intratumoral injection for ACC-SMAO. In this phase III, multicenter, non-randomized, single-arm, open-label trial, we recruited eight hospitalized patients with ACC-SMAO between October 2009 and January 2011. Within the first year, patients received PTS injection for 2–3 sessions weekly, with 2 weeks as a single course. Pre- and post-treatment assessments, including vital sign assessment, dyspnea index, chest computed tomography (CT), were performed shortly before PTS injection and at day 30 post-treatment. We extended the observation to 5 years to determine overall survival. The primary endpoint was the CT-assessed airway objective response rate (ORR) at day 30. The key secondary endpoint was the overall survival (OS) at 5 years post-treatment. At baseline, mean airway tumor cross-sectional area was 153.3 mm² (n=8), and the mean airway obstruction rate was 86.1%. The airway ORR reached 100% (33.3% complete remission and 66.7% partial remission). PTS treatment reduced the airway tumor size from 158.2 to 22.7 mm² and the average airway obstruction rate decreased from 83.1% to 14.4% (n=6). The 5-year overall survival rate was 50.0%. Median survival duration was 4.98 years (range, 1.39–5.00 years). Four patients (50.0%) had stable disease. Compared with baseline dyspnea index, the transitional dyspnea index increased significantly at 30 days after treatment (mean difference: 5.40; 95% CI, 0.31–10.49; P<0.05). Adverse events were reported in 75% of patients (n=6), of whom 33.3% (n=2) and 66.7% (n=4) were rated as mild and moderate, respectively. No SAE was reported. In conclusion, PTS could rapidly debulk ACC-SMAO, resulting in considerable improvement of five-year survival rate.