Phase I trial of neoadjuvant dasatinib in patients with resectable malignant pleural mesothelioma

Abstract

7580 Background: The optimal multi-modality treatment for resectable malignant pleural mesothelioma (MPM) remains unknown. We designed a biomarker-based neoadjuvant trial from our preclinical studies showing that dasatinib, a multi-targeted Src kinase inhibitor, has activity against MPM and target specificity to Src Tyr419. Methods: Untreated MPM patients underwent extended surgical staging (ESS) with multiple biopsies to account for tumor heterogeneity, lymph node status and to rule out sarcomatoid features. If deemed a surgical candidate for either pleurectomy/decortication (P/D) or extrapleural pneumonectomy (EPP), patients received 4 weeks of oral dasatinib (70 mg BID) followed by P/D or EPP. If either a radiographic or molecular response (de-phosphorylation of Src Tyr419 in tumor) is achieved, an additional 2 years of dasatinib maintenance after adjuvant radiotherapy and systemic chemotherapy is given. The primary endpoint of this trial was biomarker modulation of Src Tyr419. Secondary endpoints included response, survival, safety/toxicity, and biomarker modulation in tumor/serum/platelets/pleural effusion. The total planned sample size is 24 to detect a 50% reduction in positive p-Src Tyr419 expression with 80% power, one-sided 10% type I error rate, and 10% inevaluable rate. Results: To date, ten patients have registered on the trial (4/08 - 12/08); six have successfully completed the ESS, neoadjuvant dasatinib, and P/D (n=3) or EPP (n=3). Two patients are still receiving neoadjuvant dasatinib; and 2 patients were deemed to not be surgical candidates due to a rapid decline in PS and one was found to have bilateral mesothelioma. The main side effects to dasatinib were grade 1–2: anemia, nausea, vomiting, anorexia, electrolyte abnormalities, fatigue, and anxiety. Grade 3 toxicities included hyperkalemia (1), infection - pneumonia (1), and hypoxia (1). There were no grade 4–5 toxicities. Post-surgical grade 3 toxicity included anemia, electrolyte abnormalities, arrhythmia, HTN, and pleural effusion; one grade 4 episode of hyperglycemia was seen. Conclusions: This study demonstrates that biomarker-based neoadjuvant MPM trials with novel agents are feasible. Updated clinical and translational correlative results will be presented. No significant financial relationships to disclose.