Benefit-Risk Assessment of Sunitinib in Gastrointestinal Stromal Tumours and Renal Cancer

Sunitinib is a novel, oral, multi-targeted tyrosine kinase inhibitor with antiproliferative effects against cancer cells and antiangiogenic properties. Sunitinib was recently approved for the first-line treatment of patients with advanced renal cell carcinoma (RCC) and for the treatment of patients with gastrointestinal stromal tumours (GIST) after disease progression or intolerance to imatinib therapy. The main purpose of this benefit-risk assessment is to review data on sunitinib efficacy along with its toxicity in patients with GIST and RCC. Sunitinib demonstrates a high level of efficacy with acceptable tolerability using either the 50 mg daily oral dosing for 4 weeks every 6 weeks or a continuous daily administration schedule at a lower dose. Hypertension and asthenia appear to be the most common adverse effects with sunitinib. Diarrhoea, anorexia, disgeusia, stomatitis and skin toxicity are other clinically relevant toxicities. Fatigue may, at least in part, be related to the development of hypothyroidism during sunitinib therapy. Skin toxicity consists of bullous lesion in the soles and palms that may require treatment discontinuation for a few days and/or dose reduction. Thyroid hormone levels should be monitored during treatment with sunitinib, with the occurrence of clinical signs of hypothyroidism needing treatment with levothyroxine sodium. Hypertension usually requires standard antihypertensive therapy and treatment discontinuation is less frequently necessary. Mild neutropenia and thrombocytopenia usually require no intervention. A decrease in left ventricular ejection fraction is a rare but potentially life-threatening complication. Although usually well tolerated, sunitinib needs to be administered cautiously with medical follow-up in patients with cancer to prevent, avoid and treat adverse effects in order to improve patient compliance. Its established antitumor activity requires attempting to maintain the highest tolerable dose in individual patients. Current oral formulations allow physicians to modulate dosages (between 25 and 50 mg/day) and/or schedules (4 weeks on, 2 weeks off or continuous administration) to optimize the benefit-risk profile of sunitinib in individual patients.