A phase II study of the efficacy and safety of sunitinib in treatment-naïve and pretreated Japanese patients (pts) with metastatic renal cell carcinoma (mRCC)

Abstract

16108 Background: Sunitinib malate (SU) is an oral multitargeted receptor tyrosine kinase inhibitor that is approved multinationally for the treatment of advanced RCC. A multicenter phase II trial of SU in Japanese pts with mRCC has recently been completed; here we report efficacy and safety data from this trial. Methods: mRCC pts with prior nephrectomy received sunitinib 50 mg/day p.o. on a 4-week on, 2-week off schedule in 6-week cycles. Primary efficacy endpoint was objective response rate (ORR) as determined by RECIST. Secondary endpoints included progression-free survival (PFS) and time to tumor response (TTR). Responses were determined every 6 weeks (wks) by computed tomography/magnetic resonance imaging. Toxicity assessments were undertaken every 2 wks (NCI-CTCAE version 3). Results: In total, 51 Japanese pts received SU, comprising 25 treatment-naïve pts (1st-line group) and 26 pts who had received prior cytokine-based therapy (pretreated group), for a median of 4 and 5 cycles, respectively. In the intention-to-treat population, ORR was 48.0% in the 1st-line group, 46.2% in the pretreated group and 47.1% in the overall population (independent review). Median PFS was 46.0, 33.6 and 46.0 wks in the 1st-line, pretreated and overall populations, respectively. Median TTR was 10.0 wks in the overall population, and 7.1 wks and 10.7 wks in the two arms. The most commonly observed grade 3–4 Aes were fatigue (20%), hand-foot syndrome (14%), and hypertension (12%). The most common grade 3–4 laboratory abnormalities were reduced platelet (55%) and neutrophil (51%) levels, and increased lipase levels (39%). In total, 37 pts required dose reductions and 10 pts discontinued SU due to Aes. Conclusions: These data show significant efficacy and tolerability with SU in Japanese mRCC pts. Although Aes were generally manageable and reversible, there was a trend towards higher efficacy and a higher incidence of some Aes in Japanese pts compared with previously reported international phase II/III trials with mostly Western pts; this potential difference remains to be clarified. It is strongly suggested that SU is effective and tolerable for the treatment of Japanese pts in the 1st- and 2nd-line settings. No significant financial relationships to disclose.