Comparison of randomized phase II studies (RP2s) and subsequent randomized controlled studies (RCTs) using identical systemic therapies
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e17515 Background: Previous research has shown that results from single-arm phase 2 studies are poor predictors of results from subsequent RCTs. It has been suggested that RP2s are more efficient in predicting outcomes of RCTs, and RP2s have increasingly been used in evaluating novel agents or therapeutic strategies. We attempted to determine if results from RP2s were concordant with outcomes of RCTs. Methods: We searched Medline and Cancerlit for RP2s evaluating systemic therapies for advanced solid malignancies, published from January 2000 to October 2008. Each publication was reviewed and a search was conducted for RCTs using identical therapies. Results of each RCT were reviewed and determined to be either “positive” or “negative” based on whether the stated primary endpoint of the study was met. Additional data such as year of publication, journal impact factor, number of patients enrolled, whether multiple centers were involved, response rates (RR), and survival data were collected. The rate of concordance between RP2s and RCTs was determined and univariate analyses were performed to determine potential predictors from RP2s of “positive” RCTs as well as concordance. Results: A total of 196 RP2s meeting study criteria were identified. However, only 16 had corresponding RCTs. Among these 16 RCTs, 11 showed concordance with RP2s results, for a rate of 68%. There was a moderately strong association between RRs from RP2s and corresponding RCTs, with a mean difference in RR of -3.8% (95% CI -10.6 to 3.0%). The difference in median survival was 1.0 mo (95% CI -1.0 to 3.2) and for time to progression it was -0.5 mo (95% CI -1.0 to 1.1) between RP2s and RCTs. No characteristics from RP2s could predict positivity or concordance with RCTs. Conclusions: Based on this small size of RP2s and RCTs, results from RP2s have relatively high concordance with results from RCTs. However, there were no significant predictors of concordance. No significant financial relationships to disclose.
