‘Real-world’ sunitinib findings support trial results

Results of postmarketing follow-up in Japanese patients confirm the efficacy and safety profile of sunitinib in advanced renal cell carcinoma (RCC).

The findings, which are based on obligatory postmarketing monitoring in Japan, included 1689 patients with unresectable or metastatic RCC who were treated with sunitinib between June 2008 and November 2009.

The researchers, led by Sang-Yoon Lee (Pfizer Japan, Tokyo), found that the efficacy and safety profile in their study was broadly similar to previous reports in Asian or Japanese patients.

They note that it is difficult to compare overall survival (OS) as the follow-up did not reach median OS; however, the 24-week OS of 84% compares with previously published 1-year OS rates of around 68%.

Median progression-free survival (PFS) was 22.7 weeks and the median duration of treatment was 22.1 weeks. The researchers found that median PFS was significantly longer among patients with a higher relative dose intensity (RDI) during the first 6 weeks of treatment, at 23.1 weeks for those with an RDI of at least 70% and 18.6 weeks for those with a lower RDI.

The findings also show that several adverse event biomarkers were associated with improved survival. The 24-week OS rate was significantly higher among patients with hand–foot syndrome (94 vs 77%), hypertension (87 vs 76%), hypothyroidism (87 vs 82%), leukopenia (91 vs 78%), and thrombocytopenia (87 vs 76%) compared with those without; this was also consistent with earlier studies.

The researchers also note that, for patients in whom the lungs were the sole site of metastases, PFS and OS were similar to patients with no metastases (89 vs 88%), a finding echoed in a recently published analysis of clinical trial results.

The results also indicate that certain adverse events, such as myelosuppression and hand–foot syndrome may be more common in Asian patients than in others, in agreement with previous research. In this study, the rate of grade 3 or worse reduced platelet count was 34% compared with just 9% in the Western Phase III study. Hand–foot syndrome, of any grade, was reported in 37% patients.

Writing in the Japanese Journal of Clinical Oncology, Lee and colleagues say that they hope their findings could lead to new biomarkers that will improve the use of sunitinib in RCC.

“[I]n addition to confirming the clinical benefit with sunitinib in this population, this study has provided important hypothesis-generating and supporting information on predictive markers for efficacy and prognosis, which may help individualize and optimize use of sunitinib in this RCC patient population”, they conclude.

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