Rare diseases clinical trial design

When the patients who received a drug candidate have the disease manifestations completely eradicated and experience no other effects while patients treated with a placebo have a continuation of the disease process, the evaluation is not difficult. However, that is rarely, if ever, the case, and evaluation requires detailed statistical analysis of the collected data. An ICH guide-line covers statistical issues related to the scope of clinical trials, design techniques to minimize bias, types of clinical trial designs, conduct considerations, data analysis for efficacy, evaluation of safety and tolerance, and reporting. 

Products for a rare disease or condition may be too small to recover their development and registration cost from sales. If this situation is expected, the developer may ask the FDA for written recommendations for the required preclinical and clinical trials. In addition, the manufacturer and sponsor can ask for an official designation as "orphan drug" (also for biological products). Orphan drugs are entitled to tax reductions and a 7 year monopoly on their use for the designated indication. 

Haffner M E (1998). Designing clinical trials to study rare disease treatment. Drug Info J 32 957-960. 

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