Phase III Trial of Paclitaxel Plus Carboplatin With or Without Tirapazamine in Advanced Non–Small-Cell Lung Cancer: Southwest Oncology Group Trial S0003

Abstract

Purpose Tumor hypoxia confers chemotherapy resistance. Tirapazamine is a cytotoxin that selectively targets hypoxic cells. We conducted a phase III clinical trial to determine whether the addition of tirapazamine to paclitaxel and carboplatin offered a survival advantage when used in the treatment of patients with advanced non–small-cell lung cancer (NSCLC). Patients and Methods Of 396 patients registered, 367 eligible patients were randomly assigned to either arm 1 (n = 181), which consisted of treatment every 21 days with paclitaxel 225 mg/m2/3 h, carboplatin (area under the curve = 6), and tirapazamine 260 mg/m2 in cycle 1 (which was escalated, if tolerable, to 330 mg/m2 in cycle 2), or arm 2 (n = 186), which consisted of paclitaxel and carboplatin as in arm 1 with no tirapazamine. Results Patient characteristics were similar between the two arms. There were no statistically significant differences in response rates, progression-free survival, or overall survival. Patients on arm 1 had significantly (P < .05) more abdominal cramps, fatigue, transient hearing loss, febrile neutropenia, hypotension, myalgias, and skin rash and were removed from treatment more often as a result of toxicity than patients in arm 2 (26% v 13%, respectively; P = .003). More than 40% of patients did not have the tirapazamine dose escalated, primarily because of toxicity. The trial was closed early after an interim analysis demonstrated that the projected 37.5% improvement in survival (8 v 11 months median survival) in arm 1 was unachievable (P = .003). Conclusion The addition of tirapazamine to paclitaxel and carboplatin does not result in improved survival in advanced NSCLC compared with paclitaxel and carboplatin alone but substantially increases toxicity.