Prospective, randomized, and controlled clinical trials have been inuse for nearly three quarters of a century1 andare the cornerstone of rational drug development.2,3 Infact, the Food and Drug Administration and other health authorities generallyrequire that at least 2 prospective, randomized clinical trials demonstratetherapeutic efficacy prior to granting approval. Such pivotal trials are timeconsuming and expensive. Recent estimates suggest that pivotal, or phase 3,trials routinely recruit hundreds to thousands of patients, typically take2 to 4 years to complete, and commonly cost $30 to $50 million. Phase 3 trialsalso expose large numbers of patients to the risk of drug-related adverseeffects. For these reasons, pharmaceutical companies, the Food and Drug Administration,and international health authorities have adopted a staged approach to newdrug testing in humans.
Cunningham ET, da Silva L, Harrison EM, Modi MW, O'Shaughnessy D, Guyer DR. Accelerated Drug Development Through Combined Phase 2/3 Clinical TrialDesign. Arch Ophthalmol. 2004;122(7):1043-1044. doi:10.1001/archopht.122.7.1043