Introduction

C-reactive protein (CRP) is a potential biomarker for renal cell carcinoma (RCC) (Saito K, Nat Rev Urol, 2011). The dynamic change of CRP levels, CRP kinetics, is associated with survival of patients with metastatic RCC (mRCC) in the cytokine era. We previously reported that early CRP response could predict overall survival (OS) for mRCC patients treated with tyrosine kinase inhibitors (TKI) in EAU congress 2016. In this study, we further explored whether the early CRP response could predict progression-free survival (PFS) and response rates (RR) with more number of cases.

Methods

A total of 103 patients (80 men and 23 women) were treated with TKI for mRCC from 2008 to 2013 at our institutions. Overall, 43 and 60 patients were treated with sunitinib and sorafenib, respectively. Fifty patients (49%) had received prior immunotherapy, and 69 patients (67%) had undergone nephrectomy previously. Baseline CRP elevation was defined as a level of 10 mg/L or more. Patients were divided into three groups according to their early CRP kinetics: patients whose baseline CRP levels were <10 mg/L (non-elevated group), patients whose baseline CRP levels were 10 mg/L or more and had decreased by more than 20% 4 weeks after the initiation of TKI (early CRP responder), and the remaining patients (non-early CRP responder). The endpoints were OS, PFS and RR.

Results

The median follow up period was 21 months (range 1 to 79 months). Baseline CRP levels were elevated in 41 patients (40%). Among these 41 patients, 19 (18%) were early CRP responder. The 1-year OS and PFS rates for the entire cohort were 69% and 40%, respectively. The 1-year OS rates of non-elevated group, early CRP responder, and non-early CRP responder were 79%, 62%, and 36% (p < 0.001). The 1-year PFS rates of these three groups were 50%, 23%, and 10% (p < 0.001). In multivariate analysis, the early CRP kinetics assessment was a significant independent factor for OS and PFS. Though there were no significant differences in the objective response rates between these three groups (p = 0.56), significantly more patients had progressive disease in the non-early CRP responder (p = 0.02).

Conclusions

Early CRP response at 4 weeks is predictive of survival for patients with mRCC treated with TKI.

Funding

none