Clinical Trial Failures of 2026

Key Takeaways

• Phase II terminations doubled between 2013‑2023, driven by business decisions
• Merck/Eisai’s LITESPARK‑012 missed progression‑free and overall survival gains
• Theravance will cut operating expenses ~60% after ampreloxetine failure
• Biogen continues diranersen development despite Phase II miss
• AI‑backed firm Biossil raised $70 M to revive failed drug candidates

Pulse Analysis

The persistent low success rate of drug development—about five percent across all phases—reflects the intrinsic scientific uncertainty and escalating costs of modern therapeutics. Phase II remains the most attritional checkpoint, where efficacy signals must be convincing enough to justify the massive investment of a Phase III trial. Recent analyses show that industry‑sponsored terminations in late‑stage studies have roughly doubled over the past decade, often because companies reprioritize portfolios in response to shifting market dynamics or competitive pressures.

2026 proved especially sobering, with several marquee programs missing their primary endpoints. Merck and Eisai’s LITESPARK‑012 failed to improve progression‑free or overall survival in advanced renal cell carcinoma, while Immunovant’s batoclimab did not achieve the required proptosis reduction in thyroid eye disease. Theravance’s ampreloxetine and Quince’s eDSP both fell short in rare‑disease indications, prompting Theravance to slash costs by about 60% and Quince to halt development. Even Gossamer Bio’s seralutinib, which showed a modest six‑minute‑walk improvement, could not meet statistical thresholds, highlighting how incremental benefits often prove insufficient for regulatory approval.

Despite these setbacks, the industry is adapting. Companies are leveraging mixed readouts to refine target populations, adjust dosing, or combine therapies, as seen with Biogen/Ionis’s continued pursuit of diranersen and Roche’s ongoing breast‑cancer programs. Meanwhile, AI‑driven platforms like Toronto‑based Biossil are attracting significant capital—$70 million—to re‑evaluate abandoned candidates, suggesting a growing belief that data‑rich, computational approaches can uncover hidden value in failed trials. This dual strategy of selective continuation and innovative rescue efforts will shape pipeline management and investment decisions in the years ahead.