Hand–foot syndrome (HFS) as a potential biomarker of efficacy in patients (pts) with metastatic renal cell carcinoma (mRCC) treated with sunitinib (SU).
320 Background: HFS and related skin toxicities are common side effects of tyrosine kinase inhibitors such as SU, a multitargeted inhibitor of VEGF and PDGF receptors plus other receptor tyrosine kinases. In a randomized phase III trial of treatment-naïve mRCC pts, SU showed superior progression-free survival (PFS) and objective response rate (ORR) over interferon-alfa, with a median PFS of 11 mo and median overall survival (OS) of 26.4 mo, establishing SU as a reference standard of care (Motzer et al, 2009). In this retrospective analysis, correlations between SU-associated HFS and efficacy endpoints were investigated in mRCC pts from 5 clinical trials in the first- and second-line treatment settings. Methods: Analyses included pooled data from 770 pts who received single-agent SU as 50 mg/d on a 4-week-on/2-week-off schedule (n=544; 71%) or 37.5 mg continuous once-daily dosing (n=226; 29%). Median PFS and OS were estimated by Kaplan–Meier methods and compared between pts with vs without HFS using a log-rank test. ORR was compared by Pearson's chi-square test. Tumor response was assessed by investigators and adverse events were recorded regularly. Multivariate and time-dependent covariate analyses were performed. Results: Of 770 pts, 179 (23%) developed any-grade HFS, compared with 591 (77%) who did not. Most instances of HFS (63%) initially occurred during the first 3 treatment cycles. Pts who developed HFS had significantly better ORR (55.6% vs. 32.7%), PFS (14.3 vs. 8.3 mo), and OS (38.3 vs. 18.9 mo) than pts who did not develop HFS (p<0.0001). In a multivariate analysis, SU-associated HFS remained a significant independent predictor of both PFS and OS (and of OS by time-dependent covariate analysis). Conclusions: In mRCC pts, SU-associated HFS was significantly and independently associated with improved clinical outcomes. Overall, pts who did not develop HFS still had substantial benefit from SU. However, the presence of HFS identified a subset of pts that manifested highly favorable efficacy results with SU. These findings suggest that development of HFS may serve as a predictive biomarker of SU efficacy, although prospective validation is warranted. [Table: see text]