Co-occurring adverse events enable early prediction of progression-free survival in metastatic renal cell carcinoma patients treated with sunitinib: a hypothesis-generating study

Aims and background: Clinical practice shows significant differences in treatment outcomes and toxicity of sunitinib across patients. This retrospective study assessed early predictive markers for progression-free survival (PFS) in patients with metastatic clear cell renal cell carcinoma (RCC) treated with sunitinib in the first-line setting. Methods: We evaluated 28 patients with stage IV clear cell RCC (with good or intermediate MSKCC risk prognosis) treated at the Department of Oncology, University Hospital, Cracow between 2008 and 2013. Data included demographic profiles, adverse events during first cycle of therapy, treatment delays, and treatment outcomes. Sunitinib was administered on a standard schedule (50 mg/day, 4 weeks on, 2 weeks off). PFS values were estimated with the Kaplan-Meier method and compared using the log-rank test; we identified independent PFS predictors using multiple Cox regression models. Results: PFS was significantly longer in patients who experienced at least 1 adverse event after the first cycle of sunitinib (median 17.6 months vs. 5.6; p = 0.006). Hypertension and hand-foot syndrome were significantly correlated with longer PFS (29.3 vs. 6.0 months; p = 0.002, and not reached vs. 9.8 months; p = 0.002, respectively). We observed a similar (though not significant) tendency for neutropenia (17.5 vs. 8.4 months; p = 0.055). In multiple Cox regression, hypertension was the only individual independent predictor of PFS, but the co-occurrence of any 2 or 3 sunitinib-induced adverse events also predicted longer survival. Conclusions: Although small, our study suggests that hypertension and hand-foot syndrome predict longer PFS in patients with clear cell RCC treated with sunitinib. The co-occurrence of 2 or more side effects seems also a significant predictor of longer survival. Larger studies are warranted to confirm the correlation between co-occurring side effects and PFS.