ArticleThe oncologist2026
Radiographic progression-free survival as a surrogate endpoint for overall survival in first-line ARPi naïve metastatic castration-resistant prostate cancer.
Article in The oncologist, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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8 authors.
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Abstract
backgroundOverall survival (OS) is the gold standard endpoint in oncology trials but requires long follow-up and may be confounded by post-protocol treatments. Radiographic progression-free survival (rPFS) is used as an earlier endpoint in metastatic castration-resistant prostate cancer (mCRPC). This study evaluated the validity of rPFS as a surrogate for OS in first-line, asymptomatic/mildly symptomatic, androgen receptor pathway inhibitor (ARPi) naïve, mCRPC using methods recommended by Germany's Institute for Quality and Efficiency in Health Care (IQWiG). MATERIALS AND
methodsA systematic search in Ovid® identified randomized controlled trials reporting both rPFS and OS. Trial-level rPFS-OS correlations of hazard ratios (HRs) were calculated using bivariate random-effects meta-analysis (BRMA) and weighted linear regression (WLR). Correlation strength was interpreted per IQWiG criteria. The surrogate threshold effect (STE) was estimated to assess surrogacy. Leave-one-out cross-validation (LOOCV) assessed model robustness. The primary analysis included trials meeting the proportional hazards (PH) assumption. Sensitivity analyses included trials violating PH and further excluded outliers outside the 95% confidence intervals (CIs) in the correlation plot.
resultsEleven RCTs were identified. The primary analysis (n = 10 trials) yielded medium correlations (BRMA R2: 0.78 [95% CI: 0.53-0.90]; WLR R2: 0.65 [0.40-0.90]; STE: 0.83). Sensitivity analyses yielded medium (n = 11 trials) and strong (n = 8 trials) correlations. LOOCV showed good predictive accuracy (75%-82%).
conclusionResults suggest rPFS is a valid surrogate for OS in first-line ARPi naïve mCRPC per IQWiG criteria. A statistically significant OS effect can be inferred for a trial demonstrating an upper confidence limit of HR < 0.83 in rPFS.
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