BACKGROUND: Emerging agents blocking the programmed cell death 1 (PD-1) pathway 
show activity in metastatic clear cell renal cell carcinoma (mRCC). The aim of 
this study was to evaluate the efficacy and safety of vascular endothelial 
growth factor (VEGF)/VEGF receptor (VEGFR)-tyrosine kinase inhibitor (TKI) 
therapy after PD-1 inhibition.
PATIENTS AND METHODS: Patients with mRCC treated with anti-PD-1 antibody (aPD-1) 
monotherapy or in combination (with VEGFR-TKI or ipilimumab) that subsequently 
received VEGFR-TKI were retrospectively reviewed. The efficacy end points were 
objective response rate (ORR) and progression-free survival (PFS) stratified by 
the type of prior PD-1 regimen. Safety by the type and PD-1 exposure was also 
evaluated.
RESULTS: Seventy patients were included. Forty-nine patients received prior 
therapy with immune checkpoint inhibitors (CPIs) alone and 21 had combination 
therapy of aPD-1 and VEGFR-TKI. Overall, ORR to VEGFR-TKI after PD-1 inhibition 
was 28% (19/68) and the median PFS was 6.4 months (mo) (4.3-9.5). ORR to 
VEGFR-TKI after aPD-1 in combination with VEGFR-TKI was lower than that in 
patients treated with VEGFR-TKI after CPI alone (ORR 10% versus 36%, P = 0.039). 
In the multivariable analysis, patients treated with prior CPI alone were more 
likely to achieve an objective response than those treated with aPD-1 in 
combination with VEGFR-TKI (OR = 5.38; 95% CI 1.12-26.0, P = 0.03). There was a 
trend toward numerically longer median PFS in the VEGFR-TKI after the CPI alone 
group, 8.4 mo (3.2-12.4) compared with 5.5 mo (2.9-8.3) for those who had 
VEGFR-TKI after aPD-1 in combination with VEGFR-TKI (P = 0.15). The most common 
adverse events (AEs) were asthenia, hypertension, and diarrhea.
CONCLUSIONS: The efficacy and safety of VEGFR-TKIs after PD-1 inhibition were 
demonstrated in this retrospective study. The response rate was lower and the 
median progression-free survival was shorter in those patients who received 
prior PD-1 in combination with VEGFR-TKI. PD-1 exposure does not seem to 
significantly influence the safety of subsequent VEGFR-TKI treatment.