On-treatment C-reactive protein control could predict response to subsequent anti-PD-1 treatment in metastatic renal cell carcinoma

The aim of this study was to evaluate the clinical significance of the on-treatment C-reactive protein (CRP) status during systemic treatment as the predictive marker for the response of subsequent nivolumab monotherapy in patients with refractory metastatic renal cell carcinoma (mRCC). A total of 73 mRCC patients treated with nivolumab were retrospectively reviewed. We evaluated the serum CRP levels before and after molecular-targeted treatments. Patients whose CRP did not exceed baseline value were defined as the CRP-control group and the others were defined as the CRP-progression group. The clinical impact of CRP-control on the efficacy of nivolumab was assessed. Twenty-four patients (33%) were categorized into the CRP-control group. The CRP-control group patients (median PFS not reached) had significantly longer PFS than the CRP-progression group (median PFS 11.9 months, 95% confidence interval, CI 4.1–19.8, p = 0.038). The CRP-control group had a tendency of longer OS from nivolumab initiation than the CRP-progression group (p = 0.071). By multivariate analysis, the on-treatment CRP-control was the independent predictive factor for PFS (hazard ratio HR 0.37, 95% CI 0.14–0.99, p = 0.047). The on-treatment CRP-control could be the predictive factor for the efficacy of nivolumab in refractory mRCC patients.