Overall, research and development expenses relating to developing drugs amount to billions of dollars. A 2012 study found that research and development of a drug is riskier than product development in other industries because it is lengthy, costly, and highly uncertain, particularly due to unpredictable human physiological responses to drugs. As an example, in 2018, Roche spent $11 billion for research and developmental expenses, and had two failed Phase III trials for an Alzheimer's drug candidate.