Background: The use of sunitinib at conventional doses (50 mg/d, 6-week cycles: 4 weeks of treatment, then 2 weeks of no treatment) in Asian patients with metastatic renal cell carcinoma (mRCC) is associated with high real-world toxicities.
Patients and methods: Patients with mRCC treated with sunitinib between 2005 and 2012 at 4 centers representing a near-national cohort (n = 160) in Singapore were evaluated. One hundred twenty-seven consecutive patients in 1 center were treated with a novel attenuated-dose sunitinib regimen (37.5 mg/d, 6-week cycle: 4 weeks of treatment, then 2 weeks of no treatment) with outcomes captured in a prospective registry. Efficacy and safety outcomes of these patients were compared against those who received sunitinib at conventional dosing (n = 33) at all 4 centers. Statistical modeling was adjusted for baseline prognostic criteria and therapy line where possible.
Results: Overall survival from treatment initiation (OSinitiation), overall survival from the first documented metastasis (OStotal), and progression-free survival (PFS) were similar for patients who received first-line sunitinib for conventional relative to attenuated dose regimens (OSinitiation: 18.3 vs. 16.5 months, respectively; P = .54; OStotal: 27.4 vs. 21.8 months, respectively; P = .45; PFS: 6.7 vs. 7.9 months, respectively; P = .64), similar to real-world outcomes in Western studies. A marked lower rate of severe toxicities, dose delays, and reductions were observed with the attenuated dose regimen, with 75/127 (59%), rather than 28/33 (85%) for the conventional dose arm who experienced Grade ≥ 3 toxicities (P = .0088); 31/127 (24%) rather than 19/33 (58%) who experienced dose delays (P = .0004); and 44/127 (35%) rather than 23/33 (70%) who experienced dose reduction (P = .0005) during their course of treatment.
Conclusion: An attenuated dose regimen of sunitinib yielded comparable real-world efficacy outcomes, with considerable reduction in toxicities as documented in a prospective registry.
Keywords: Dose modification; Kidney cancer; Pharmacokinetics; Real-world outcomes; Targeted therapy.
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