Phase II study of first-line bortezomib and cisplatin in malignant pleural mesothelioma and prospective validation of progression free survival rate as a primary end-point for mesothelioma clinical trials (European Organisation for Research and Treatment of Cancer 08052)
O'Brien MER., Gaafar RM., Popat S., Grossi F., Price A., Talbot DC., Cufer T., Ottensmeier C., Danson S., Pallis A., Hasan B., Van Meerbeeck JP., Baas P.
This was a prospective phase II study of cisplatin and bortezomib (CB) in the first line treatment of malignant pleural mesothelioma (MPM) with validation of progression free survival rate at 18 weeks (PFSR-18)1 as primary end-point. Methods Chemotherapy-naïve patients with histologically proven MPM and performance status (PS) 0/1, were treated with cisplatin 75 mg/m 2 on day 1 and bortezomib 1.3 mg/m2 on days 1, 4, 8, 11 every 3 weeks. The primary end-point validation utilised the landmark method. Results Between 2007 and 2010 82 patients were entered. PFSR-18 was 53% (80% confidence intervals, CIs, 42-64%). The overall survival (OS) was 13.5 months (95% CI 10.5-15) with 56% (95% CI 44-66%) alive at 1 year. The median PFS was 5.1 months (95% CI 3.3-6.5) and the response rate was 28.4% (95% CI 18.9-39.5%). The most frequent grade 3-4 toxicities were hyponatremia (46%), hypokalaemia (17%), fatigue (12.2%), thrombocytopenia (11%), neutropenia (9.7%) and neurotoxicity (motor, sensory, other: 1.2%, 8.5%, 2.4%). There were two toxic deaths (32 and 74 days) due to acute pneumonitis and cardiac arrest. End-point validation showed that patients with no progression/progression at 18 weeks had median OS of 16.9/11.9 months, respectively. Hazard ratio was 0.46 (CI 0.32-0.67), logrank test and C-index were 0.007 and 0.60. Conclusion The 50% PFSR-18 for CB was contained within the 80% CI for (42-64%). Therefore the null hypothesis could not be rejected. Accordingly this combination does not warrant further investigation. PFSR-18 was confirmed as a strong predictor of survival. © 2013 Elsevier Ltd. All rights reserved.