A Science.org analysis reveals clinical trial failure rates have increased significantly over recent decades, raising concerns about drug development efficiency. The blog post examines historical data showing that despite advances in technology and biology, the probability of a drug candidate successfully navigating clinical phases has not improved—and in many therapeutic areas, has worsened.

Key findings highlight Phase II as the primary bottleneck, where efficacy failures dominate. Oncology and neurology programs exhibit particularly high attrition, with success rates often below 10%. The analysis suggests that target validation, biomarker development, and patient stratification remain critical gaps.

Industry experts argue that regulatory pressures, complex biology, and reliance on surrogate endpoints contribute to the trend. Some advocate for adaptive trial designs, real-world evidence integration, and earlier go/no-go decisions to improve productivity. The data underscores a persistent "valley of death" in translational research.