Progression-free survival as a predictor of overall survival in metastatic renal cell carcinoma treated with contemporary targeted therapy.

BACKGROUND

The majority of metastatic renal cell carcinoma (mRCC) clinical trials that examined targeted agents used progression-free survival (PFS) as the primary endpoint. Whether PFS can be used as a predictor of overall survival (OS) is unknown.

METHODS

Patients from 12 cancer centers who received targeted therapy for mRCC were identified. Landmark analyses for progression at 3 months and 6 months after drug initiation were performed to minimize lead-time bias. A proportional hazards model was used to assess the utility of PFS for predicting OS.

RESULTS

In total, 1158 patients were included. The median follow-up was 30.6 months, the median age was 60 years, and the median Karnofsky performance status was 80%. For the entire cohort, the median PFS was 7.6 months, and the median OS was 19.7 months. In the landmark analysis, the median OS for patients who progressed at 3 months was 7.8 months compared with 23.6 months for patients who did not progress (log-rank test; P < .0001). Similarly, for patients who progressed at 6 months, the median OS was 8.6 months compared with 26 months for patients who did not progress (P < .0001). Compared with those who did not progress, for the patients who progressed at 3 months and at 6 months, the hazard ratios for death adjusted for adverse prognostic factors were 3.05 (95% confidence interval, 2.42-3.84) and 2.96 (95% confidence interval, 2.39-3.67), respectively. Similar results were demonstrated with landmark analyses at 9 months and at 12 months and in the bootstrap validation. Kendall tau rank correlation and a Fleischer model demonstrated a statistically significant dependent correlation.

CONCLUSIONS

PFS at 3 months and at 6 months predicted OS, and the current results indicated that PFS may be a meaningful intermediate endpoint for OS in patients with mRCC who receive treatment with novel agents.