Phase I study of sunitinib in combination with gemcitabine and capecitabine for first-line treatment of metastatic or unresectable renal cell carcinoma.

Background: The combination of gemcitabine plus capecitabine and sunitinib (GCS) shows activity in metastatic renal cell carcinoma (mRCC). We tested the multitargeted "chemo-switch" regimen as first-line treatment in patients with mRCC.

Methods: We assessed the maximum tolerated dose and antitumor activity of GCS in treatment-naïve, advanced mRCC patients. Treatment consisted of intravenous gemcitabine on days 1 and 8, oral capecitabine twice daily on days 1-14, and oral sunitinib daily for six 21-day cycles, followed by sunitinib monotherapy at the investigator's discretion. Dose level 0 (DL0) was gemcitabine 1,000 mg/m(2) per day plus capecitabine 650 mg/m(2) per 12 hours plus sunitinib 37.5 mg/day; DL1 was gemcitabine 1,000 mg/m(2) per day plus capecitabine 850 mg/m(2) per 12 hours plus sunitinib 37.5 mg/day.

Results: Sixteen patients were enrolled. At DL1, two of four patients had dose-limiting toxicity (DLT; grade 3 diarrhea and grade 4 thrombocytopenia). The dose was reduced to DL0 when only 1 of 12 patients experienced DLT (grade 3 diarrhea, grade 3 mucositis, and grade 3 thrombocytopenia). Dose reductions were frequent (58% of patients), and only seven patients were able to receive the three drugs for more than three cycles. One patient achieved a complete response, three had partial responses, and the best response for four was stable disease.

Conclusion: The safety profile of the combination does not seem manageable in this patient population. No further development of the combination is recommended.