Pazopanib after sunitinib failure in patients with metastatic renal cell carcinoma.

BACKGROUND: Sunitinib is a standard agent for the treatment of metastatic renal cell carcinoma (mRCC). The objective of the study was to evaluate efficacy and safety of pazopanib in the treatment of patients whose mRCC either progressed on sunitinib or who discontinued sunitinib due to adverse effects.
MATERIAL AND METHODS: Thirty-one consecutive mRCC patients who received pazopanib after sunitinib failure were included in this retrospective single center study. Pazopanib was continued until disease progression or intolerance. Treatment response was evaluated every 8-12 weeks according to the RECIST criteria. Adverse events were recorded according to the Common Terminology Criteria for Adverse Events.
RESULTS: Six patients (19%, 95% CI 12-26%) achieved partial response with pazopanib, 18 (58%) had stable disease, and seven (23%) progressive disease as their best response. Of the 14 patients who received pazopanib as their second-line therapy, six (43%) responded as compared with no responses among 17 patients treated in a later line (p = 0.004). The median progression-free survival time was 7.4 months after starting pazopanib (range, 0.9-15.6 months). Patients who received pazopanib as second-line treatment had median progression-free survival of 11.0 months as compared with 3.8 months among those who received pazopanib in a later line (p = 0.031). Only one (3%) patient discontinued pazopanib due to an adverse event. The most commonly recorded adverse events were anemia, thrombocytopenia, diarrhea, fatigue, and elevation of serum creatinine concentration. Six (19%) patients had one or more grade 3 or 4 adverse events recorded.
CONCLUSION: Pazopanib has clinical activity in mRCC as second-line agent after sunitinib failure suggesting lack of complete cross-resistance. Pazopanib was associated with acceptable toxicity, and may be considered as an option after sunitinib failure.