The Value of the Information That Can Be Generated: Optimizing Study Design to Enable the Study of Treatments Addressing an Unmet Need for Rare Pathogens.

In traditional phase 3 trials confirming safety and efficacy of new treatments relative to a comparator, a 1-sided type I error rate of 2.5% is traditionally used and typically leads to minimum sizes of 300-600 subjects per study. However, for rare pathogens, it may be necessary to work with data from as few as 50-100 subjects. For areas with a high unmet need, there is a balance between traditional type I error and power and enabling feasible studies. In such cases, an alternative 1-sided alpha level of 5% or 10% should be considered, and we review herein the implications of such approaches. Resolving this question requires engagement of patients, the medical community, regulatory agencies, and trial sponsors.