Success Rates and Timelines of African-Inclusive Phase III Trials: A Retrospective Analysis

Background/Objectives: Phase III trials are critical for evaluating therapeutic efficacy and safety, but African site inclusion has historically been limited, raising questions about generalizability and efficiency. This retrospective study aimed to analyse success rates and timelines of Phase III trials incorporating at least one African site compared with established global benchmarks. Methods: 461 publicly reported Phase III trials completed between December 2014 and December 2024 with ≥1 African trial site were retrospectively reviewed. Trials were categorized as oncology or non-oncology, and primary endpoint outcomes (positive vs. negative) and durations from initiation to primary endpoint completion were analysed descriptively. Results: Overall, 69.6% (95% CI, 65.5%-73.7%) of the trials samples achieved positive primary endpoints. Non-oncology trials (n=359) had a higher success rate (73.5% [95% CI, 69.0%-78.0%]) than oncology trials (n=102; 55.9% [95% CI, 46.3%-65.5%]). Both rates exceed or align with global benchmarks (historically ~58–67% overall, ~26–40% oncology). Mean trial duration was 1,085 days (95% CI, 1036-1135 days), shorter than typical global durations (~1,200 days). Oncology trials had longer timelines (mean 1,366 days [95% CI, 1268-1465 days]) than non-oncology trials (mean 989 days [95% CI, 936-1042 days]), but remained within global norms. Conclusions: Phase III trials including African sites demonstrated robust primary endpoint success rates and competitive timelines compared to global norms, notably outperforming historical oncology success rates. Stakeholders should cautiously consider broader African inclusion to improve diversity and global relevance of clinical trial data.