Efficacy and safety of sunitinib alternate day regimen in patients with metastatic renal cell carcinoma in Japan: Comparison with standard 4/2 schedule

Aim Sunitinib is a standard agent for metastatic renal cell carcinoma (mRCC). The standard schedule, 4 weeks‐on followed by 2 weeks‐off (4/2 schedule), often does not maintain an adequate dosage because of the severe adverse events (AEs). We compared the efficacy and safety of an alternative every other day (q.a.d.) dosing with that of the 4/2 schedule in mRCC patients. Methods Of the 55 Japanese patients, 32 and 23 were administered 4/2 (standard group) and q.a.d. schedules (50 or 37.5 mg, every other day; experimental groups), respectively. The AEs, anticancer effects, and trough plasma concentrations of sunitinib were compared between them. Results The most common AE in the standard group was thrombocytopenia (43.2%), but it was observed in only two patients in the experimental group (8.7%). Although leukopenia and hand‐foot syndrome were both detected in six patients (18.8%) in the standard group, no patients had these AEs in the experimental group. The incidence of dose interruption in the experimental group (21.7%) was significantly lower than that in the standard group was (59.4%, P = 0.005). Time to progression (TTP) and overall survival (OS) of the experimental group were better than those of the standard group (P < 0.001 and P = 0.002, respectively). Mean plasma levels in the experimental group (64.83 ng/mL) were significantly lower than those in the standard group (135.82 ng/mL, P < 0.001) were. Conclusion Sunitinib administered q.a.d. was safe and effective for mRCC patients. We speculate that the persistent optimal drug plasma concentrations contributed to these effects.