Correlation between the magnitude of best tumor response and patient survival in nivolumab therapy for metastatic renal cell carcinoma

The correlation between the magnitudes of best tumor response (bTR) and patient survival in immune checkpoint inhibitor therapy for metastatic renal cell carcinoma (mRCC) remains unclear. In this article, we retrospectively investigated the prognostic association of the magnitude of bTR in nivolumab therapy for mRCC. Fifty-five patients treated with nivolumab after failure of at least one molecular-targeted therapy were evaluated. Assessment of the magnitude of bTR was based on the Response Evaluation Criteria in Solid Tumors (RECIST) v.1.1. Endpoints were progression-free survival (PFS) and overall survival (OS) after the initiation of nivolumab therapy. In regard to the magnitude of bTR, complete response, partial response, stable disease, and progressive disease were observed in three (5.46%), 15 (27.3%), 19 (34.5%), and 18 (32.7%) patients, respectively. PFS and OS were significantly correlated with the magnitude of bTR (median PFS: not reached (N.R.) [95% confidence interval (CI) 16.8–N.R.] vs. 13.0 [8.38–56.0] vs. 5.95 [4.27–7.30] vs. 1.92 [0.53–3.91] months, p < 0.0001; OS: N.R. [N.R.–N.R.] vs. N.R. [21.4–N.R.] vs. 23.3 [23.3–N.R.] vs. 7.36 [1.41–N.R.] months, p < 0.0001). In addition, multivariate analyses show that the magnitude of bTR was an independent factor for PFS (p < 0.0001) and OS (p = 0.0010). In conclusion, this retrospective study shows the significant correlation between the magnitude of bTR and patient survival in nivolumab therapy for mRCC. The magnitude of bTR can be an effective surrogate marker for survival.