"Report To The President On Propelling Innovation In Drug Discovery, Development, and Evaluation, prepared by the Presidentís Council of Advisors on Science and Technology (PCAST). This report responds to your request for recommendations on this topic...Despite major breakthroughs for some diseases, many of the most common human diseases are not effectively treated by existing therapies. Many common malignancies, including lung cancer, colon cancer, breast cancer, and prostate cancer are incurable once they have metastasized. Ninety-six percent of orphan diseases, including rare cancers, lack effective therapies. Despite current therapies, heart disease and stroke remain leading causes of mortality. Infectious diseases remain an important challenge with the emergence of antibiotic-resistant bacteria and multi-drug resistant tuberculosis, and the possibility of new viral pandemics that could cause widespread mortality. Psychiatric diseases remain a tremendous burden on society, and existing treatments have limited efficacy. Alzheimerís disease, which already afflicts more than 5 million people in the United States, at a direct cost of an estimated $200 billion in 2012, including $140 billion in Medicare/Medicaid payments, is increasing in prevalence as the population ages; some observers project that in the absence of new effective therapies the economic burden of Alzheimerís may ultimately exceed $1 trillion per year."