A phase II study of sunitinib in recurrent and/or metastatic adenoid cystic carcinoma (ACC) of the salivary glands: current progress and challenges in evaluating molecularly targeted agents in ACC

Background Vascular endothelial growth factor (VEGF) and c-kit are highly expressed in adenoid cystic carcinoma (ACC) and associated with biologic aggressiveness. This study aimed to assess the antitumor activity of sunitinib, a multi-targeted inhibitor of vascular endothelial growth factor receptor, c-kit, platelet-derived growth factor receptor, ret proto-oncogene (RET) and FMS-like tyrosine kinase 3 (FLT3), in ACC of the salivary gland. Patients and methods Patients with progressive, recurrent and/or metastatic ACC were treated with sunitinib 37.5 mg daily in this single-arm, two-stage phase II trial. Response was assessed every 8 weeks. Results Fourteen patients were enrolled on to the study. Among 13 assessable patients, there were no objective responses, 11 patients had stable disease (SD), 8 patients had SD ≥6 months and 2 patients had progressive disease as best response. Median time to progression was 7.2 months. Median overall survival was 18.7 months. Toxic effects occurring in at least 50% of patients included fatigue, oral mucositis and hypophosphatemia usually of mild to moderate severity. Conclusions Although no responses were observed, sunitinib was well tolerated, with prolonged tumor stabilization of ≥6 months in 62% of assessable patients. The lack of responses is comparable with other trials of molecularly targeted agents in ACC and highlights the need for novel strategies in phase II clinical trial design.